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DECK FINISHES COATINGS PRESERVATIVES
EIFS & STUCCO EXTERIORS
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FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
LEAD POISONING HAZARDS GUIDE
LEAD PAINT REMOVAL ALTERNATIVES
LEAD PAINT REMOVAL TROUBLES
PAINT & STAIN GUIDE, EXTERIOR
SLIDE PREPARATION, MICROSCOPE
STAIN & BIODETERIORATION AGENT CATALOG
STAINS on & in BUILDINGS, CAUSES & CURES
STAIN DIAGNOSIS on BUILDING EXTERIORS
STAIN DIAGNOSIS on BUILDING INTERIORS
STAINS & FINISHES, INTERIOR
STUCCO PAINT FAILURES
TEST KITS for DUST, MOLD, PARTICLE TESTS
TRIM, EXTERIOR CHOICES, INSTALLATION
VAPOR BARRIERS & CONDENSATION in BUILDINGS
WALL SIDING TRIM & FINISHES
WALL FINISHES INTERIOR
Paint failure causation, diagnosis, cure: this article series explains the diagnosis, cause, cure and/or prevention of all types of paint failures on buildings. We discuss paint analysis and reviews common building exterior & interior painting mistakes, describes how to diagnose paint failures on buildings, and outlines a procedure for diagnostic field inspection & lab testing of failed painted surfaces. We include photographs of paint failures on buildings and more photos of forensic paint laboratory examination of samples of failed paint useful to assist in diagnosing the probable cause of each type of paint failure.
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The examples discussed in this paint failure analysis article use building exterior paint failures (and remedies), but many interior paint failures and even some paint failures on artworks, paintings and artifacts are similar their origin and cure.
In discussing the procedure and value of analysis of paint samples to diagnose the cause and cure of failures, here we include both our own field and laboratory experience and procedures and also paint problem diagnostic information provided by some paint manufacturers, home improvement suppliers, historic building and historic conservation experts such as the U.S. NPS, art conservation experts, and by National Forest Products Laboratory experts.
We will discuss paint sample analysis procedures using microscopy and microchemistry, and typically working with small chips of paint removed from a surface, provides useful paint and coating information for several different purposes, including historical paint information, paint failure diagnostic analysis on buildings, and art conservation. We describe these just below.
Paint analysis for paint failure diagnosis
Analysis of paint from art works and artifacts
Analysis of paint from art works and artifacts: can provide information invaluable to art conservators, including distinguishing among causes of paint failures and in suggesting conservation methods.
Working with museum conservators such as Ulrik Runeberg, Museo de Arte Contemporáneo de Puerto Rico, San Juan, we have found that forensic analysis of small surface samples of stains, using simple adhesive tape sampling can provide useful art conservation information without requiring punch samples or paint chip samples. Our photo (above right) of a closeup of the surface of a painting whose surface was flaking was provided courtesy of Mr. Runeberg and formed part of a joint investigation into the adhesion failure of paint in this work.
On superficial examination at only low magnifications, microbiological deterioration of art works, such as due to fungal attack, can be confused with other causes of spots, blotching, or staining in works of art, such as extractive bleeding from pressed hardboard substrates.
Material identified as hardboard fibers from a stained painting surface (photo, above left) sampled from the painting En Aire, in the Museo de Arte Contemporáneo de Puerto Rico, San Juan, was obtained using clear adhesive tape and the particle sampling method (also used for mold testing) described at TEST KITS for DUST, MOLD, PARTICLE TESTS.
Those painting surface samples helped to prove that in many cases the staining of acrylic paintings on fiberboard are an unlucky combination of the artist´s habit to apply only a single layer of paint and the humid conditions in which many works had been stored. - U.R. Understanding the cause of stains on art works helps direct the best course of action for both cleaning and preservation.
Other Paint Analysis Methods: Additional chemical and age testing of paints are performed by paint manufacturers in developing these products. Other much more costly types of paint sample analysis, such as pyrolysis-gas chromatography can provide specific product identification signatures of basic modern paints and can list their constituents;
Fourier transform infrared spectroscopy for paint analysis, direct temperature-resolved mass spectrometry may also be used. But a skilled analyst trained in field investigation and forensic microscopy can address questions of paint layer color, history, and most causes of paint failures quickly, economically, and sometimes more reliably.
PAINT FAILURE CHECKLIST - Typical Considerations in Evaluating Paint Failures
Also see PAINTING MISTAKES.
Experts representing paint manufacturers see many field failures of painted surfaces, often arising from a common cause. But getting a clear answer from these professionals can be tricky: the painting contractor is their customer, not the building owner.
Therefore, while most paint failures are due to poor surface preparation or painting in improper conditions of temperature or moisture, the "expert" may be reluctant to say so. Importantly, other paint failures are due to construction errors, building ventilation or vapor barrier errors, building leaks, or improper maintenance. It is important to understand why a paint failure occurred before re-painting a building. Otherwise the expense of a new paint job may be wasted.
Our 1984 photo (left) shows the website editor D. Friedman (at rear) and Art Cady preparing surfaces of a home for painting. Prepping soft wood shingle surfaces that have been previously painted is horrible work and very labor intensive.
"Improper or inadequate surface preparation is by far the most common cause of house paint failures such as blistering, peeling and staining. If the new paint is separating from the old coat of paint, it is most likely due to chalking or some contaminant on the old paint that prevents the new paint from penetrating and binding to the old painted surface. If the peeling failure is down to the bare wood, it is most likely that the problem is a result of too much moisture within the wall, forcing itself out, taking the entire paint film with it."
"Over 65% of all paint failures can be attributed to poor or improper surface preparation. Two of the major causes of paint failure on exterior wood surfaces are either moisture passing through the substrate from the interior, or exterior sources of moisture getting behind the paint film. Temperature and humidity have major effects upon drying and ultimately upon the characteristics of the paint film.
These effects will always determine the actual appearance and performance of the paint itself. Paint should be applied at temperatures of 70o F, (21o C), ideally, plus or minus 20o F (12o C) - unless product specifications state otherwise. A surface should not be painted if its temperature is within 5o F of the dew point or the relative humidity is above 85%." -- PPG Exterior Failures.
But you don't need fourier transform nor any other sophisticated paint analysis to understand the paint job shown just above. The West end of this New York home (inspected by DJF ca 2000) is believed built by Derick Hegeman 1759-1769, and the East end was added by Thomas Storm or John Adriance (all of Ducthess County, NY) 1769 - 1794. The home was purchased by George Brinckrerhoff in 1795. It looks as if almost all of the coats of paint are still present in some of the really thick layers on this wall clapboard.
The follow sections of this document form a checklist of building and site conditions leading to paint failures (such as peeling paint, blistering paint, chalking paint, cracking or alligatoring paint, or bleeding and stains through paint--terms defined below). The focus is on failures of painted wood surfaces on building exteriors but the paint failure diagnostic procedure can be generalized to other surfaces inside and out.
Here is our list of clues that help diagnose the cause of exterior building paint job failure. If you are diagnosing an indoor paint problem see PAINT FAILURE - INTERIOR CLUES. The photo below shows the author (on roof) working with Arthur Cady during a house painting project in New York. A photo of the finished paint-job is at SHORTCUT ERRORS. Additional clues that can help diagnose an outdoor paint problem are at STAIN DIAGNOSIS on BUILDING EXTERIORS.
Quotes in the opening text of this document are from the encyclopedic but not quite complete paint website: PPG Exterior Failures http://www.ppg.com/getpaint/etraining/solver/exterior.html
Related articles: Readers should also see Paint Failure Case Photographs-SITE and then Paint Failure Case Photographs-LAB and see PAINT & STAIN GUIDE, EXTERIOR for a guide to the selection and proper application of paints and stains on exterior wood surfaces.
See PAINT FAILURE INDICATORS for more detail when invasive inspecting is permitted.
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Technical Reviewers & References
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Reference Texts for Paint & Fiber Forensic Analysis, Diagnosis, Conservation: