Carpet stain diagnosis questions & answers:

FAQs about how to determine the cause of various types of stains and stain patterns found on carpets and rugs.

Why light spots, bleach spots, or dark spots or other colors show up as stains or discoloration or loss of pigment on rugs and carpets.

This article series describes how to identify and diagnose carpeting stains at the edge of carpets near walls in buildings focusing on the cause of various interior wall and ceiling stains and explains how to recognize thermal tracking, thermal bridging stains, building air leaks, and building insulation defects.

Stains & Marks on Carpeting - Diagnostic FAQs

These questions & answers about diagnosing the cause of stains on carpets and on stain removal were posted originally at CARPET STAIN DIAGNOSIS - be sure to review that article

On 2020-10-22 - by (mod) -

That looks like a prior spill or a pet urine stain.

More examples are at WOOD FLOOR DAMAGE REPAIR

and at

ANIMAL STAINS & MARKS in BUILDINGS

On 2020-10-22 by cj

I removed the carpet from a pre-owned home and found these black marks on the bedroom's hardwood floor. Its black and kind of hard to tell if its mold. There are some parts of the carpet foam sticking to this spot on the floor but no foul smell whatsoever.

Mold or stain? Thanks

On 2020-08-31 - by (mod) -

That looks like splash marks from a cleaner. Bottom line, I don't know, Belinda.

On 2020-08-28 by Belinda

Hi, I have these green patches popping up on our carpet. We built 8yrs a go and I’ve noticed it over the years but it’s becoming more frequent & I’m finding them popping up in strange places like under beds, where carpet meets tiles etc.

On 2020-08-26 by kim

Can you help me? I have the same situation with my area rug.

I have the same issue with the random spots appearing after my dhurrie rug was cleaned.

Anyone have any ideas what they are and how to remove them?

On 2020-07-27 - by (mod) -

Was the carpet cleaned with water, steam, chemicals?

On 2020-07-27 by Marie

We had our carpet cleaned a month ago and ever sense we have seen random green spots appear. They don't appear at the same time but its very weird and we dont know where they are coming from.

On 2020-07-09 - by (mod) - old carpet stains at corners

Please find your photo and question that you posted at CARPET STAIN DIAGNOSIS

You'll help me out by posting just once. Thanks

DF

On 2020-07-09 by Matt

Hello, I'm looking at buying a house and it has these stains on the carpet. It looks like mold but I'm not sure

On 2020-06-14 - by (mod) - small red stains appear overnight on carpet

Ciara

I'm not sure what those reddish spots are on your carpeting; blood from an injured cat's foot is a possibility as is a spill, something tracked in on shoes, or a yeast growth if the carpet was wet.

On 2020-06-13 by Ciara Ward

Hello, these spots randomly appeared overnight on my carpet. I am unsure if they are blood spots or something else. I do have a cat, but do not see any wounds on her or any of our feet. What do you guys think it is?

On 2020-05-27 by Kristen

Hi. Thanks. Yes I suspected that this might be the case. I will let it dry out completely and see what it looks like then. It may have to be a strategically placed rug for a while. It is a large lounge and I wouldn't be able to consider the cost of changing it just now. Thanks for your help. Kirsten

On 2020-05-27 - by (mod) - I treated this carpet for black mold and the stain keeps coming back

Kirsten

I suspect that when you put your gym equipment onto the carpet it felt "dry" but the deeper carpet backing and perhaps padding below were still wet or damp, leading to a mould growth stain.

You might be able to have the area professionally cleaned but, sorry to say, in general mouldy carpet can not be effectively cleaned nor rid of mould. Almost always it is instead, replaced.

Aside: "Black mould" concern is an unfortunate error promoted by people selling products and services to the public who were made frightened of "black mould " by inaccurate reporting.

There are millions of mold genera/species and hundreds of them commonly found in and on building surfaces. Some of those are dark in colour but many other, often more-harmful moulds may be other colours: green, white, red, brown, yellow, orange .

On 2020-05-27 by Kirsten Miller

I cleaned my lounge carpet and once it was dry I put my gym equipment in there.

I moved a few things a couple of days later and found a greenish discolouration. I tried vacuuming it but nothing changed. Over the next couple of days it became black.

I cleaned it again but as it dried out it just started turning black again.

I treated it with black mould treatment and it removed it impressively however, as it is drying out it is again becoming black. Help!!

On 2020-03-23 by Anonymous

It is! Thanks - that was what I was thinking too. I would hate to experiment and make it worse. Sometimes things need to be god enough! Take care and thanks for your help! God bless ya!

On 2020-03-22 - by (mod) -

I'd live with the color perhaps experimenting with re-arranging the furniture; beware that area rug edges on carpet can be a trip hazard.

Worrying about carpet color is a welcome relief from the pandemic.

On 2020-03-22 by Anonymous

Thanks Dan! What would you do if you were me! It’s a pretty dark red. Suggestions. Or just leave it be. My husband unfortunately just lost his job / so replacing it any time soon is not in the plan. Thanks again!! Stay healthy! Isn’t this all crazy and surreal what’s going on in the world? Vicki

On 2020-03-22 - by (mod) - how can I change the color of this red carpet?

Vicki

Carpets can be dyed and on occasion cleaning a carpet will lighten its color - depending largely on the actual fabric materials, carpet age, and carpet condition.

Watch out: you can dye a light colored carpet darker but you cannot dye a dark colored carpet lighter. I would not try a carpet dye on a carpet whose color is already pretty dark.

Watch out about trying any bleaching procdure on dark carpeting: in my exprience it's easier to make an old carpet uniformly darker than lighter as any bleaching effort is likely to produce uneven results.

Alternatives to chlorine bleach & carpet dyes to lighten a carpet:

You might try this procedure (it's success depends on the type of carpet fibre, dye used, and initial colour).
(The colour of synthetic fibres are more difficult to change. Only wool carpets and nylon carpets will accept most dyes.)

Starting in a hidden or at least not-obvious area of the carpet, mix 1 cup of distilled white vinegar into a1 gallon of warm water and spray the carpet test area evenly enough to wet the top of the carpet fibres. Let the carpeting dry, check for a color change.

If you like the result you can try a larger area.

You're likely to also need to have the carpeting cleaned to remove the vinegar smell.

References for carpet dye sources

AmeriColor Carpet Dyes & Chemicals, PO Box 463, Newberg OR 97132 USA, Tel: 503-538-0111
info@americolordyes.com website: http://americolordyes.com/

Sun-Belt-USA Aramsco, Carpet Dye Chemicals Tel: 1-800-662-8836 Web:https://www.sun-beltusa.com/chemicals/carpet-dyeing-chemicals.html Offices in Raleigh & Wilmingto NC

On 2020-03-22 by Vicki

We have really old - I mean really old / red carpet but can’t afford to replace it . Is there anyway I could change the tone if this red and make it more rust colored to match this area rug? Just trying to think of a cheaper solution to get it to blend better! Any ideas? Suggestions! Thanks / Vicki

On 2020-01-09 by (mod) - yellow mold that keeps popping up

Linda

I would like to see some sharp photos of the fungus that you're talking about. You can post one photo for each comment but of course you can post multiple comments.

In any event except for a couple of unusual and special cases. I'm not likely to blame the mold genera and species but rather a leak condition somewhere that has not been correctly identified and repaired or an incomplete cleaning of a prior mold problem in the building, or both..

On 2020-01-0 by linda

we have a yellow mold that keeps popping up (like a cottage cheese consistancy)... we had the area professionally cleaned by a disaster specialist who had never seen it before... nothing seems to help keep it from coming up....

On 2019-11-04 by (mod) -

Rosie

To me that looks like an area of the carpet that was cleaned using a cleaner that removed some of the carpet's original colour OR the whole carpet is rather old and was somewhat uniformly soiled (this can happen, for example in sooty cities like New York City) and then just one area was cleaned.

You might try having the whole carpet cleaned by a professional.

On 2019-11-04 Rosie

Hi, I have this carpet and am wondering what this patch could be. At first I thought it was sun damage but it seems to be in a weird spot. Upon further inspection, it is light from one angle and dark from another. What could it be and how can I treat it?

Thanks

On 2019-07-02 by (mod) - light-bleached carpet stains

Unfortunately the very light spots are most-likely actually light-bleached - pigment has been lost.

Cleaning won't restore the original color. It's possible to try to color in the light areas to more-closely match the rest of the carpet using a dilute fabric dye but frankly it's quite difficult to match the original.

On 2019-07-02 by Anonymous

thanks for getting back to me so promptly.
Your assumptions are correct.

The apartment building itself is not new, circa 1970? We are not the first occupants since this carpet was laid, there was definite evidence of the discolouration ahead of us first occupying (2 years ago).

The darker, unimpaired areas of carpet are places where furniture was positioned - this furniture didn’t sit directly on the floor, apart from small feet, the furniture sits 100-150mm above the carpet surface.

Ergo I suppose the carpet beneath the furniture was in shadow but not isolated from moisture, temperature, other elements, etc.

We didn’t apply any harsh cleaners to the carpet at any point, spot cleaning if it was required would’ve been with water and *maybe* a carpet shampoo/cleaner?

Thanks again for your help!

On 2019-06-2 by (mod) -

Thanks for the interesting question and photo, Matthew.

While light exposure and foot traffic are definitely sources of area discolouration on carpets, the light colored round spots in your photo, such as the closeup I'll include below, are characteristic of spills of something, possibly followed by use of a bleaching or oxidizing cleaner on that spot. The effects of an oxidant on fabric can show up and increase over time and may not appear visually until months after its application.

Can you confirm that

1. this is not a new building
and thus

2. you are not the first occupants of this apartment
and

3. that the carpet was in the apartment when you moved-in

If so, a reasonable guess is that someone tried cleaning up spills or stains left by a previous tenant.

Different is the darker rectangle of carpet in front of the dark-painted wall in your photo. More-likely that's an area that was previously covered by furniture and so was less exposed to traffic and light. The fact that there's an oval area of what looks like more-worn carpet in front of the darker rectangle is consistent with foot traffic there.

On 2019-06-24 by Matthew

Hi there, we are renting an apartment in Sydney (AUS) and our grey carpet has been turning orange over time.

The discolouration is evident near doorways (external and to the en-suite), windows and generally light-exposed areas however there are a few spots where there is heavily localised, significant staining.

We are certain there have been no spills to cause these but can’t determine any other contributing factor?

FYI: Directly below the slab is an out-door covered carpark

On 2019-01-31 by (mod) -

You will need to experiment; try fabric dyes at your local fabric store supplier.

On 2019-01-31 by Anonymous

Thank you. What is diluted dye and where can I buy.

On 2019-01-31 1 by (mod) -

Sandra,

Various spills besides actual bleach can cause bleached-out white spots on carpeting, such as a bit of lemon juice, hydrogen peroxide, various spray cleaners.

One can experiment with dilute dyes and a cotton swab, first testing on an unobtrusive carpet section.

On 2019-01-31 by Sandra

I have white bleach looking spots appear on my carpet. I don’t use any bleach cleaners in my house for exactly this reason. I do have a dog. I’m just bewildered. Is there an option of fixing besides replacing carpet. Thank you.
IMAGE LOST by older version of Clark Van Oyen’s useful Comments code - now fixed. Please re-post the image if you can. Sorry. Mod.

On 2019-09-16 by (mod) - small brown stains on carpet + possile thermal tracking or air leaks

Mary I see two discolorations, I darker area along the carpet close to the wall which sometimes is caused by an air leak and those small reddish stains that could be from a spill. Was there previously furniture or some other fixture placed in this location?

On 2019-09-16 by Mary

What may cause this on my carpet it’s in my bedroom also

On 2019-05-08 by (mod) -

I'm not sure, Jessica - the photo is a b it blurry, but the darkness right at the edge of the carpet suggests there could be an air leak or air and moisture leak around the room perimeter.

On 2019-05-07 by Jessica

Hello, what would be causing this on carpet in a closet/bedroom that is on the second story of a home?
IMAGE LOST by older version of Clark Van Oyen’s useful Comments code - now fixed. Please re-post the image if you can. Sorry. Mod.

On 2019-04-30 by (mod) -

I wish I could be of more help Rebecca that from just your text I can't really make a useful guess. What's the age of the carpets, what's the age of the home, and is it possible that they were previous spills, or leaks from above or below?

On 2019-04-30 by Rebecca

We’re getting weird spots all over the caret, but mostly in the living room. We’ve been in the house about a year and they started appearing about 4 months aha. At first we thought they were pet stains but cleaning doesn’t help. They are roundish, maybe 2-3 inches across and the area feels stiff. It’s a mobile home

On 2019-04-13 by (mod) -

It's not likely to be led but there could be a house dust deposit if those areas were blocking heat or air flow or conversely, if there was an air leak from below. I need to see more to have a more clear opinion

On 2019-04-13 by lacysmithlhs

This looks and comes up like its pencil lead?? It was only on exposed carpet behind crib and a chair.. did not travel under furniture.. thermal tracking ??
IMAGE LOST by older version of Clark Van Oyen’s useful Comments code - now fixed. Please re-post the image if you can. Sorry. Mod.

On 2019-02-24 by (mod) -

It is indeed a puzzle.
Perhaps something hygroscopic spilled

On 2019-02-24 by Coolcastle

Hi a small corner of our rug under the dinning table is damp. We dried the rug in the sun and put that corner near the glass door. Mysteriously, that same corner now shifted to near the glass door is damp! The other corner is dry! Any one can help with a scientific explanation?

On 2019-01-22 by (mod) -

I think I would start by looking for a leak or condensate or other moisture Source in that location.

On 2019-01-20 by Ceci

The carpet and tile are at the 1st floor, on concrete slab. Where the carpet meets the tile there is an area tha is getting green

Question: how to diagnose the cause of dark stains under the surface of new carpeting

2019/01/23 Heather said:

We have just moved into a newly constructed house. After four weeks we are noticing dark spots coming from the bottom of our carpet. As the weeks progressed, we are noticing in all three carpeted rooms.

The heavy traffic areas appear to be "revealing" the dark spots.

There is NO discoloration on the top of the carpet fibers/threads.

Carpet/home all under warranty and will be replaced, but I am more concerned of the "why" and don't want to have same upgraded carpet/padding installed if this could be a pattern. Many thanks for any guidance.

Reply: checklist for diagnosing stains below the top surface of new carpet

Heather:

It would be helpful to know:

- the age and location of the home - just when it was completed, when you moved in

- the type of construction: is this floor on a concrete slab or over a basement or crawl area

- the conditions under the floor if you're over a crawl space or basement

- the type of heating system: oil or gas, and whether or not woodstoves or fireplaces are in use

- are there other potential sources of dark dust and debris or soot: pets, prior water entry, leaks, spills

Next

When the carpet is removed

1. Cut and preserve a square foot of the most-stained carpeting - for possible further analysis

2. Inspect the under-side of the carpet for stains or marks and photograph those - and show us the images

3. Inspect the carpet padding for stains or marks and photograph those - and show us the images

4. Inspect the subfloor after carpet and padding have been removed, and look for stains, water entry, etc. and photograph those - and show us the images

I do not suspect that the problem is innate with the carpet itself, but we don't know that, for example somebody didn't install "new" carpeting that actually had been used or installed elsewhere first, or that had been improperly stored or damaged or wet.

It's also the case that normal household vacuuming removes ONLY surface dust and debris, so if the carpet had been soiled by even normal foot traffic, or by other dust or soot sources, and if someone tried to clean it, that cleaning would only have removed the top soiling.

(Oct 20, 2018) (mod) said: could bleach stain our carpet orange?

Bleach, even diluted can certainly turn carpet to a lighter color including Orange.

It's just about impossible, economically, to restore it to its exact original color although sometimes you can find a guy that gets close.

(Oct 20, 2018) Gina said:

My grey carpet has orange stains. My daughter bleaches and dyes her hair. How do I know if the stain is from orange dye or bleach? How do I get it grey again?

On 2018-04-14 by (mod) - possible sources of black spots on carpets

I can't say, Marvin but I'd be looking for an improperly operating oil or gas fired heating appliance, or wet / damp conditions and mold growth. Use the "Add Image" button below the comments box to show us some photos if you like.

On 2018-04-14 by Marvin Feiges

We woke up this morning and saw about 50 black spots the size of a nickle and a quarter. Then later we saw more black spots on small rugs in other rooms ? What is this coming from. There is no smell, but feel a bit greasy. please help.

On 2018-01-22 by (mod) - small spots where the carpet is lighter

Perhaps a spray or spill of a cleaner or drink. You're welcome to attach a photo using the icon next to the Comment button.

On 2018-01-22 by Bonnie

I have a reddish brown carpet throughout my house, I have noticed small spots where the carpet is lighter, it looks like a stain but it has made the carpet lighter instead of darker, I have no clue what it could be??

On 2017-05-12 by (mod) - These stains glow white under the blacklight

Linda,

Please try our website search box just above to find our article on

Black white, and UV light uses

Where you will see a wide range of substances that the UV light will reveal.

To analyze the actual substance would require preparation of a sample of the carpeting perhaps by clipping some of its surface, having that processed by a qualified forensic Laboratory.

In my opinion, I'm not sure that that is cost Justified. However if you're concerned about the health risks associated with the carpet it would make sense to dispose of it along with padding and then to clean the floor below.

On 2017-05-12 by Linda

My son just discovered with a black light hundreds or thousands of stains and dribble track on every single carpeted room of his house. His ex-wife live there alone for more than a year during the contentious divorce. We are very certain that she deliberately spilled and dribbled a liquid as an act of vengeance.

These stains glow white under the blacklight. How do we determine what the stains? There were two dogs in the house but the pattern, number, and location of some of the stains make it virtually impossible to be dog pee.

On 2017-01-31 by (mod) - loss of pigment or light areas on carpeting - why light spots show up on carpets

Paula

We didn't hear more from Ed.

Light spots on carpets often are traced to a spill from above or a leak from below. But I've also seen color changes from

- light exposure

- exposure to drafts or air currents

- variations in carpet manufacture, dye application, causing colour changes as carpets age.

I took a look at Shaw's advice on carpet stains - if you use an iPhone there's a free iTunes store app that catalogs many stains and gives individual stain removal recommendations. If you're an Android or Chrome user you're out of luck with Shaw.

Without a guess about what is causing the stain I think the best you can do is to contact the carpet manufacturer to ask their advice. Shaw recommends that you contact Stainmaster "for spot removal and care information" at 1-800-438-7668.

Contact Shaw directly at 800-441-7429, or Shaw Industries, Inc., PO Drawer 2128, 616 E. Walnut Ave., Dalton GA 30722, ATTN: Information Center, Mail Drop 072-53. Or Website https://shawfloors.com/

But before doing anything to the light spots you describe, you'll want to determine if this is actually a "stains" - that is, discoloration or a color change caused by something foreign that has gotten on to the carpet - or if instead this situation is not from an external cause but rather is a loss of pigment from a manufacturing defect.

Use the page top or bottom CONTACT link to send me some photos for further comment: sometimes the location and pattern of a stain can give clues to its probable origin.

Depending on the pattern and location of the whitening areas of your carpet, you (or we) might call these "Bleaching Stains" - bleaching or loss of pigment can be caused by substances other than bleach, such as tracked-in de-icing salt, ice melting chemicals, some fertilizers, spills of some medications such as acne meds, spray cleaners that contain bleaching agents (perhaps used on nearby surfaces), benzol peroxide, hydrogen peroxide, and of course household bleach itself.

Where pigment has been lost the typical repair approach is to have an expert cut-out the bleached area and glue in a patch - something that may be more feasible when carpeting is new and patching material will closely match the original carpet.

Some homeowners try making up a new stain liquid that closely matches the original carpet color, trying to stain it back to close to original - not something I'd recommend before you talk with the carpet manufacturer of your particular carpeting.

Beware that if the stains are actually bleaching stains, the carpet has lost pigment and no cleaning is going to restore that.

Loss of color in carpeting, other than bleaching "stains" is most-commonly due to light exposure. Carpet vulnerability to light-bleaching - or photo-oxidation of its original pigments in my parlance - depends on the carpet fabric fiber types and on the pigment chemistry used in the carpet's manufacture. Carpet experts refer to this as "fading" not "bleaching stains".

It's easy to make a distinction: fading will occur over areas of carpet exposed to sunlight while bleaching stains more often appear as spots, small or large, perhaps irregular in shape, and not correlated with light or sunlight exposure.

Darker carpets fade more than lighter ones, in part because the darker color means more sunlight and more heat are absorbed into the carpeting while lighter carpets reflect light and heat at a higher rate. While indoor humidity and also indoor temperature levels are also factors, a primary factor is light - from the sun, typically from windows, sliding doors, patio doors, skylights, etc.

Direct sunlight oxidizes the dyes in the carpet fibers. Most of light-fading is due to UV light components in sunlight (about 40% according to some articles I reviewed), while light in the visible spectrum causes about 25% of carpet fading. Artificial light or other miscellaneous light sources cause the remaining fading.

Earlier I described homeowner attempts to re-dye a carpet. If the carpet is valuable and only on advice from the carpet manufacturer, I'd suggest hiring a professional to re-dye your carpeting if that's warranted.

Watch out: when hiring a carpet cleaning company. Some carpet cleaning firms use a bleach-solution carpet cleaning pre-spray that may later show up as light spots where the pre-treatment was applied un-evenly.

Finally - well it's never really final until one of us dies -

In woven carpeting or rugs or tapestries I have noted fading patterns that were traced to areas of prior repair. A repair of a valuable rug may involve expert re-weaving that when new is virtually invisible.

But depending on the yarn fibers and the chemistry of the dye used to match the original carpet's color, the re-woven area may fade (or may refuse to fade) in sunlight at a rate different from the surrounding carpeting or rug area.

It's easy to spot this carpet stain or fading pattern too: you'll see that though the stained or faded area may be irregular, its edges will follow weaving lines that are ultimately rather straight. flip the rug over and look at its back side to see evidence of prior repairs or re-weaving.

Carpet and rug experts list eight common stain removers. I would not use ANY of these before

1. making a good estimate of the type and nature of the stain to be removed - match the remove to the stain following instructions from the manufacturer

2. testing the stain remove in an unobtrusive or hidden area

Common stain removers include

Alcohol, Ammonia, Non-chlorine Bleach, Detergent (or in an emergency dishwasher detergent), Dry-cleaning solvent, Enzyme detergents, "POG" a paint, oil and grease remover sold at building suppliers and paint stores, and vinegar. Most of these are used in solution with clean water.

On 2017-01-31 by Paula - Small spots started to appear on their rug in the den that looked like bleach spots.

This is a question for Ed who posted a question on Oct. 10, 2014 regarding spots on his Shaw carpet that look like bleach spots. Did he ever find an answer to what was causing the spots? My daughter and son-in-law are going through this very problem.

They have brand new Shaw carpets in both their den and living room. They have NO PETS!

Small spots started to appear on their rug in the den that looked like bleach spots. They started out small in size but have gotten larger. Now they are starting to see discoloration in the living room. Just wondering if Ed could help by telling me what he found out.

Question: quarter sized bleach-like spots on the Shaw carpet

(Oct 10, 2014) Ed said:

We had a very nice plush carpet manufactued by Shaw installed in our house about 2 years ago. All was well until about a month ago when we noticed a few small discolored spots show up in the Den.

They were the size of a quarter and look like bleach spots. We blew them off as an accidental spill which we will have repaired with some extra carpet we have. A month later, 2 larger bleach colored spots have surfaced. One in the den and one in our living room. One is about 6"x6" and one is about 12" x 3". Our dog does can get to the den but not the living room.

Also we tested the dog's urine on a piece of the same carpet and it will no create this type of bleach discoloration. We do not detect any leaks in our cement slab floor that could be a possible source.

Any ideas on the cause? Could the carpet pad or adhesive cause this type of discoloration? I intend to contact the carpet retailer, but would it be best to contact Shaw Carpets and have an Shaw carpet inspector come out? Any advice wold be appreciated. Ed

Reply:

Ed:

Dog pee stains are not likely to be quarter-sized unless your dog is an unusual pee-r. I'd start by determining if the stains are coming from above or below. Careully remove carpet from its tack strips at a corner and pull it back far enough to let you see the condition of the padding and the concrete slab below the areas where the stains appear.

If there are absolutely no visual difference on the subfloor surface or padding below the stains from below non-stained areas then we're looking for a source in the occupied space.

Let me know what you find and we'll take it from there.

Watch out: I do not advise testing carpet by putting dog pee on it. The odor is hard to remove beyond the dog's ability to smell, and putting it there is telling the dog that's a good place for his or her urine.

On 2016-12-18 by Crystina - spilled water stains our carpets

Hoping someone has an answer for me. We bought a house with basic tan carpet that is probably at least 20-30 years old, maybe even older

. It looks ok, but if water is spilled on it it makes a very dark stain. Stain remover will remove it, but any water spills anywhere in the entire house make these black stains. We don't really want to replace it yet since we have small children but I worry there might be mold under the carpet.

Comment: thanks for carpet stain diagnosis help

Sept 10, 2012) MRS. R. said:

LOVE THIS SITE. NEVER knew I could find such an informative site on my problem carpet staining along the wall. It had become an embarrassing problem (housecleaning issues? I hoped not)Now I know-thermal tracking from crawl space! Thank you.

[Click to enlarge any image]

Reader question: Diagnose red spots on carpeting

I am renting in a unit in sydney.

Suddenly there are some red marks appearing in the carpet. My real state said it is ink mark but Iam sure it is not ink cause we do not have any ink in our house and it is appearing in some different placesI have attached some pics

Can u please give me idea what causes these marks. - Anonymous by private email 3/5/2018

Reply:

That looks to me like red ink or a similar product. Take a look at the fibres under a low power microscope and you'll see immediately if there is some biological growth. I suspect not.

Some of the photos you sent showed the red stain smeared and lighter on the carpet surface, suggesting prior attempts at cleaning.

Red stains like this can show up from a red ink pen or red magic marker. Sometimes red appears from other dyed objects.

There are red yeasts that can stain building surfaces but I'd not expect yeast to grow in the pattern on your floors. See RED MOLD PHOTOS

Keep in mind that sometimes a stain has been present for quite some time but was not noticed. Then when we first notice it we think it has just appeared.

On 2018-02-09 by (mod) - bleach splash marks on carpet

Michelle,

White spots appearing literally everywhere argue against "throwing bleach" or any other cleaner about since I'm doubtful you could throw spots or droplets of anything uniformly all over a carpet.

Check the condition of the carpet where it is

- protected entirely by being covered such as under a book-case or couch

- exposed to different effects like sunlight

And the owner might want to check the carpet padding and floor below as well as checking for a source of dampness or mold contamination.

Let me know what you find.

On 2018-02-08 by Michelle

Hi.. I clean a house and over the last year white spots have appeared everywhere through the house on a tan carpet ..

it is a very expensive rug but not positive of the kind .. the guy freaked yesterday saying we through bleach everywhere .. we don't use bleach .. he also claims he has never had it cleaned, which I believe. What are these?

On 2018-02-09 by (mod) - carpet seams show in photos of backer

Anne

It looks like a seam between those two different carpet underside patterns.

On 2017-12-27 by Anne carpet backing photo

Sorry for the holiday delay- here is a picture of the rug with its underside turned up. I can’t detect a seam, but what do you think? And is there something in the cleaning process that would pull out this different color? Thank you!

On 2017-12-19 by (mod) -

Anne, I have a speculative theory that what we're seeing is an artifact of the manufacture of the rug. The fact that the light area goes to the end of the rug and that it extends under the table argues against the color difference being due to light exposure or foot traffic.

Check to see if you can detect a seam in the rug at the color difference: go to one end, flip back the rug, take a photo of the underside and show me what you found.

On 2017-12-19 by Anne - photos of straight line shading on carpeting

Any idea what could have caused the discoloration in a straight line? (As seen below). It is an natural wool rug- could this be cellulosic browning or do you think it wasn’t dried properly? Thank you!

Here you go-- This is the line that I noticed after the cleaning company delivered the rug back to my house. The furniture is placed on it as it normally was (and the rug is 18 months old).

[Click to enlarge any image]

On 2017-12-04 by (mod) - attach photos of shade lines or stained carpeting

Anne

I have seen lines, discoloration, and bleeding stains in rugs that were wash by rug cleaning service and then rolled without being properly dried first. But such mistakes are uncommon.

The sorts of things that would make a straight line separating two different degrees of shading on a rug or carpet more likely would be the location of furniture or the presence or absence of sunlight.

I wanted to add that you are welcome to try posting photos one at a time by opening with a few words in the comment box and then clicking on the tiny picture frame icon to the right of the comment button. That will let you post photos individually.

On 2017-12-04 by Anne - straight line down carpets

Hello, I sent my rug out for cleaning and when it came back there was a straight line down the rug where one side was darker and one side was lighter. Could this have occurred during the cleaning process? The company is saying the rug was like that when I picked it up? If that is the case, what would cause the discoloration along a straight line? I can send pictures if needed. Thank you.

On 2017-11-13 by Dee

Just a few hours ago,we found a sudden appearance of a dry black stain on the carpet near the window covering a large part of the floor and grayish stain going up the blinds. There is also a black nickle size stain near the window seal on the wall.

There is no obvious moisture inside or outside of the window. No moisture at all on the carpet. Any idea what it might be.? It looks like mold to me.

On 2017-08-14 by (mod) -

Adam,

If you agree, I'll re-post your images here and add comments. Better if you can email me some higher resolution images. Use the page bottom CONTACT link.

Re-Posting:

(29 minutes ago) Adam said:
Hi. Any ideas as to the cause of this damage?

[link to photos on google drive]

On 2017-05-28 by Martha Brush

We don't eat or drink in the parlor. We have dark stains under the carpet pad all over the wood floor. We don't have an animal. Stains are on the walls and tile floor. They are sticky and have to be scraped. What could they be?

On 2017-04-19 by (mod) -

Normal soiling from foot traffic, or deposits near walls from air leaks?

On 2017-04-19 by Mary White

light color carpet is getting darker in places

Question: dark areas forming on cheap nylon carpet

(Dec 3, 2014) Anonymous said:
We recently moved into a house with new cheap nylon carpet. in the last month I have noted large dark areas appearing and have tried to clean them, which either makes them worse or doesn't help An ideas?

Reply:

Usually there has been a spill if the stain is in a specific rounded spot, or if it's along wall/floor edges or at HVAC registers, it's an air leak or airflow problem depositing dust and debris.

Question: big dirty stains on a carpet over an asphalt tile floor

(June 7, 2015) Bill said:

Hi we have a cream carpet on underlay we never have shoes on it but we are getting big dirty looking stains on the carpet. The floor is our lounge and it is an asphalt floor could it be asphalt stains from when it was wet cleaned? it comes back after each cleaning.
Cheers
Bill

Reply:

Bill

It might be worth taking a look under the carpeting to see if you've got water coming up from below.

Question: dark irregular stain on carpet has doubled in size and doesn't clean off

(July 27, 2015) Anonymous said:
I have a large (3x3), irregularly shaped spot in my carpet That is a darker shade than the whole carpet. It has doubled in size in 15 years and doesn't seem to respond to cleaning. What could it be?

Reply:

Perhaps a fungal or other stain response to an old spill? Spills of organic liquids, juices, milk, etc. can invite a fungal growth that might expand over time, OR the stain itself may become more apparent as dust and dirt particles stick to the area of original spill;

I'm not an expert but I've also noticed that some spills that are acidic can actually damage the carpet fibers.

Perhaps there is an air or water or moisture source under the floor in that location?

Question: stains found under the carpeting

(July 28, 2015) Anonymous said:

We purchased a new home and are in the process of pulling the carpet. There were no obvious stains on top, but the underneath in almost every room so far is almost completely covered with rust blotchy stains.

Two of the rooms had small areas on the sub-floor near the wall that looked moisture stained although they did not feel damp or test positive with a moisture meter. We are assuming pet damage since previous owner had cats and dogs, but is there anything else we should be concerned about? Something is definitely giving me a headache when I'm pulling carpet. Thank you.

Reply:

Usually pet stains are black or brown on wood flooring;

Tiny red stains around tack strips may indicate prior wet carpets or flooring that rusted the tack strip nails.

If you see rippled cupped flooring I'd assume the floor has been soaked and I'd be thinking about what happened and asking if water entered walls, wet drywall or went other naughty places that risk a hidden mold problem.

See ANIMAL STAINS & MARKS in BUILDINGS

Question: how to distinguish between carpet perimeter stains caused by rusty nails in tack strips vs. air leaks or other causes

(Aug 26, 2015) Anonymous said:
DORI HARSTON

(Oct 16, 2015) Anonymous said:
How do you know that the dark areas around the perimeter of carpets is not due to oxidization of the nails in the tack strips ?

Reply:

Good question Anon:

Nail rust or the rust of the nail tips poking up through the tack strip and grabbing the carpet back are in a regular pattern; you can pull up carpet, separating it carefully (so as not to tear the carpet) in an area of staining to look at the back of the carpeting: if the carpet has been wet or the floor below damp you may see rust spots tracking tack strip nails on the bottom of the carpeting.

Look at the carpet stain from the room side to see how that maps to what you find below the carpeting; for example, if the stains appear on the carpet room side in an area where there are no rust stains from tack strips on the carpet back then we figure the stains are not due to a wet floor below but rather some other source such as an air leak or a spill onto carpet from the room side.

Question: musty odor, now orange spots on the carpet

(May 2, 2016) Eprice said:

I have beige carpet in a cottage that we purchased a few years ago.

The house did not have a dehumidifier running when we purchased it so it had a musty odor that we are slowly getting rid of. We noticed a couple of small orange spots in various places on the carpet and didn't think much of it.

In the last year the orange spots are appearing all over in different rooms. Our plan is to eventually replace the carpet but we we want to do some remodeling too so it may be a year until we get to it. Any idea why these orange spots are appearing?

Reply:

Eprice

If there is a musty odor there is an odor source somewhere, perhaps a mold reservoir that you don't see. I'm not sure what explains the orange spots: possibly a yeast growth. I'd worry that there is moisture coming from below, and I'd check the carpet padding, the floor below that, and the under-side of that floor from below.

Question: yellow stain on carpet due to air leaks?

(Sept 1, 2016) Selina said:
I have a yellow stain I'm my daughters bedroom that is growing could this be due to air leakage

Reply:

I can't guess from just that e-text, Selina. But usually air bypass leak stains are dark in color as they're depositing house dust. Yellow? The location and pattern of the stain may be diagnostic.

Question: mysterious stains on expensive carpet

2016/09/08 Seonad-Siobhan Duggan said:

I have a very good quality wool carpet, which sees hardly any traffic whatsoever, as I don't live in the house where it is laid! It has started disintegrating for absolutely no apparent reason, other than a stain has been spotted by 2 separate experts who think it may be a spillage of some sort, although we have not spilled anything!

The experts have ruled out damp, moths or any type of bug infestation. I am wondering if such a problem, which seems to have no explanation or solution, could be fixed - the carpet is very good quality and is discontinued, so I am obviously, very disappointed not to find the route cause or solution ... any ideas ? Thanks

Reply:

Seonad

One thing upon which we can agree, a carpet won't deteriorate for absolutely "no reason". There's a reason, even if we don't know what it is.

Start by looking at what sort of "deterioration" is occurring - that's not clear from your note.
Continue by mapping just where the problem is seen.

If the deterioration is in a specific spot, what's the shape and location of that spot? Either something happened there or something spilled on or was placed on the carpet there or there's some other more rare, I'd say very very rare case of a manufacturing defect. I say rare because the way carpeting is manufactured involves large, continuous sheets of material so it'd be odd for a manufacturing defect to show up as a spot.

If the defect is over all of the carpeting then I'd look for an environmental factor: heat, moisture, airborne contaminants.

I'd also want to look at the under-side of the carpet and at the padding and at the flooring below the padding: those will give invaluable clues.

You can use the page top or bottom CONTACT link to send photos of the conditions you find and we may be able to comment further.

Finally, find and follow the live link to stain testing at the end of the article above where you see this line:

Continue reading at CARPET STAIN ID TESTS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

...

Continue reading at CARPET STAIN DIAGNOSIS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see CARPET STAIN DIAGNOSIS FAQs-2 - more-recent questions & replies on diagnosing or cleaning off stains and marks on carpeting & rugs.

Or see these

Recommended Articles

• CARPET STAIN DIAGNOSIS - home
  • CARPET AIR LEAK STAINS at WALLS
  • CARPET CONTAMINATION TEST PROCEDURE
  • CARPET DUST IDENTIFICATION
  • CARPET FUNGICIDAL SPRAY
  • CARPET MOLD / ODOR TESTS
  • CARPET OZONE MOLD / ODOR TREATMENT WARNINGS
  • CARPET PADDING ASBESTOS, MOLD, ODORS
  • CARPET STAIN ID TESTS
  • CARPET STAINS by AIR LEAKS
  • CARPET TACK STRIPS & FLOODS
• CARPETING & INDOOR AIR QUALITY
• CARPETING, SELECTION & INSTALLATION
• DUST SAMPLING PROCEDURE
• FIRST AID for PET-PEED-ON CARPETS & FLOORS
• STAINS on INDOOR SURFACES, PHOTO GUIDE

Suggested citation for this web page

CARPET STAIN DIAGNOSIS FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING STAINS

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