Asbestos content of Flinkote & Flintkote Stalwart brand buidling sheathing products:

The short answer is "no" for wood-based or plant-based products and "yes" for certain other (not plant-based) LDB or LDF products specifically described as asbestos board; the history is interesting.

This article series describes and provides photographs that aid in identifying various insulating board & fiberboard sheathing materials used on building walls and roofs.

Asbestos in FlintKote Insulating Sheathing Board?

Flintkote produced a number of asbestos-containing building products.

As we describe here, Flintkote's insulating sheathing was principaly a plant bsed product, not asbestos.

Asbestos claims ultimately led to the Flintkote company's bankruptcy.

So in general, the answer to "is there asbestos in FlintKote insulating sheathing is no, not if the sheathing product is a simple, one-layer brown plant fiber material as we illustrate on this page.

But patent research shows that at least some more complex or layered Flinkote sheathing products included asbestos.

It is quite apparent that the sheet may consist of more than two layers of the asbestos and of the Wool fiber, as for instance the layer of asbestos can be laid between the layers of Wool felt, or vice versa. - Overbury 1925 patent cited below.

Other possible, if uncommon, exceptions as we describe separately

at FIBERBOARD SHEATHING ASBESTOS CONTENT

Reader Question: does FlintKote Stalwart Sheathing contain asbestos?

2018/03/15 jessi said:

Does stalwart sheathing contain asbestos

Illustrations here and at page top: FlintKote building products, Life Magazine, 25 April, 1960.

[Click to enlarge any image]

Reply: Stalwart Sheathing, by FlintKote was principally a cellulose product but its coatings might contain asbestos

Jessi

FlinkKote's Stalwart Sheating was a cellulose-based insulating sheathing board widely used in the 1960's in North America.

From what I've been able to find the fiberboard was impregnated with asphalt and perhaps other water-resistant materials such as waxes, and often surfaced with asphalt-impregnated paper or "felt".

Some asphalt-impregnated felts contained asbestos. Generally cellulose board products did not except where cross-contaminated by having been manufactured at a facility that also handled asbestos.

An exception MIGHT be found in some FlintKote products including insulating sheathing that were coated with a bituminous layer that included vermiculite, as you'll read in the patent disclosures below.

The potential for asbestos in these products is that some vermiculite contains asbestos.

History of & Ingredients in FlintKote Sheathing

The history and ingredients in FlintKote insulating sheathing can be found, at least partially, in patent disclosures assigned to FlintKote

• Levin, Harold L. "Fibrous covering and method of making same." U.S. Patent 1,774,204, issued August 26, 1930.
  (Roofing material)
• Wegenroth, Jr Edgar R. "Process of manufacturing insulation siding." U.S. Patent 3,104,184, issued September 17, 1963.

This much-later patent citation

• Winters, Donald C., and Ivan D. Klein. "Inorganic fiber mat using mineral wool and related process and apparatus." U.S. Patent 4,532,006, issued July 30, 1985.
  describes
  
  "An improved inorganic fiber mat containing mineral wool, preferably a composite mat of mineral wool and fiberglass"
  
  And contains no mention of asbestos.

Asbestos in Flintkote Products

The Flintkote company produced roofing products containing asbestos and also asbestos-cement shingle siding. Asbestos was used in other FlintKote products including the company's ThermalKote a water resistant siding, and in fire-resistant products. For details of which FlintKote products contained asbestos

see FLINTKOTE ASBESTOS PRODUCTS GUIDE

Flintkote Insulating Sheathing Patents

These patents assigned to FlintKote give more details of the history and constituents of FlintKote insulating sheathing

• Heppes, Otto A., and Walter H. Cady. "Waterproof covering." U.S. Patent 1,574,886, issued March 2, 1926.
• Levin, Harold L. "Waterproof board and method of preparing same." U.S. Patent 1,793,810, issued February 24, 1931.
  This invention relates to improvements in plaster board commonly comprising an inner cementitious core of stucco, plaster, or the like, having outer surface coverings of absorbent paper.
  [No mention of asbestos nor vermiculite in this patent]
• Overbury, Frederick C. "Process of making roofing felt or like material." U.S. Patent 1,558,495, issued October 27, 1925.
  Excerpts demonstrating the presence of asbestos in asphalt-saturated felt:
  
  According to my invention and to meet the object thus specified, I provide a multiply sheet formed of layers of paper felt and asbestos, the fibers of the several layers being intermingled and adherent, so 25 that the sheet is an integral structure.
  
  In the manufacture of this sheet, the paper felt la er a is formed of cotton and wool or other suitable fiber in the usual manner, into a wet pulpy web,,upon which is deposited a wet pulpy web of asbestos fiber b.
  
  These may be then subjected to a felting action in a machine or apparatus of the ordinary construction, or be dried in the usual drying machine, thus producing a sheet, one ace of which is paper felt (so-called) and the other face of which is asbestos, the two layers being interlocked I together by the intermingling of their fibers without the use of any foreign binder or cement.
  
  It is quite apparent that the sheet may consist of more than two layers of the asbestos and of the Wool fiber, as for instance the layer of asbestos can be laid between the layers of Wool felt, or vice versa.
• Whitehead, James, Peter H. Reynolds, and John G. Spray. "The sub-ophiolitic metamorphic rocks of the Québec Appalachians." Journal of Geodynamics 19, no. 3-4 (1995): 325-350.
  
  Abstract & Article Excerpts:
  
  Sheared amphibolites from alongside the Pennington Sheet in the Flintkote Mine are reinterpreted as a dynamothermal sole, rather than a metasomatically generated amphibole-bearing metasediment.
  
  ...Other occurrences of amphibole-rich units along the Pennington Sheet noted by Laurent et al. (1979) have more in common with the dynamothermal soles of the Quebec Appalachians. Such an example is found at the Flintkote asbestos mine near Robertsonville (Fig. 7).
• Yamamoto, Kaname. "Thermal insulating and bituminous waterproofing board and application process thereof." U.S. Patent 4,357,377, issued November 2, 1982.
  Cites use of vermiculite (that may contain asbestos)
  Excerpt:
  The thermal insulating layer 14 is laminated on one surface of the bituminous waterproofing board. The thermal insulating layer 14 can be composed of any conventional thermal insulating materials.
  
  Examples of such thermal insulating materials are inorganic thermal insulating boards made of, for example, rock wools, slag wools, asbestos, glass fibers, calcium silicate, perlite, vermiculite, gypsum, foamed glasses and the like; foamed synthetic resins made of, for example, polystyrene, polyethylene, acrylic resin, phenol resin, urea resin, epoxy resin, diallylphthalate resin, urethane resin and the like; foamed rubbers, wood chip boards, wood wool boards and the like.
  
  The thickness of the thermal insulating material layer 14 may be varied over a wide range and is appropriately determined depending on the required heat transmission resistance.
• Yamamoto, Kaname. "Process for making a built-up thermal insulating and bituminous waterproofing assembly." U.S. Patent 4,374,687, issued February 22, 1983.

 

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2023-07-18 y InspectApedia Publisher (mod)

@Dan,

Your photo shows the identifying logo for Flintkote and in another section the word SHEATHING - that is Flintkote insulating sheathing or what some people more-genericalhy call "blackboard." It does not contain asbestos.

First please read the opening paragraphs of the article above on this page. (No asbestos in general)

Then read and compare your product with other Flintkot products at

FLINTKOTE Stalwart™ SHEATHING ASBESTOS

On 2023-07-18 by Dan

Has anyone come across this blackboard and know if it has asbestos? Thank you!

[Photo above]

This Q&A were posted originally

at SHEATHING, FIBERBOARD ASBESTOS CONTENT 

On 2023-04-08 by SUSAN Z HYDE

Is this flintkote product in your data base. does it contain asbestos

On 2023-04-08 by InspectApedia Publisher (mod)

@SUSAN Z HYDE,

Thank you for the question and the photo of Flintkote Insulating sheathing board.

That certainly looks like a plant fiber based sheathing product which as you will read In the article above, would not be expected to contain asbestos.

...

Continue reading at FLINTKOTE ASBESTOS PRODUCTS GUIDE select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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Citations & References

In addition to any citations in the article above, a full list is available on request.

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