Paint Analysis - Peeling Paint? How to Diagnose, Correct, & Prevent Paint Failure on Buildings InspectAPedia® -
Analysis of small paint samples provides the history of paint layers & colors on buildings & can diagnose the cause of paint failures
How to diagnose the cause of failing paint on a building exterior or interior
Paint sample analysis uses in art conservation: diagnose stains, failures, conservation needs
Paint failure diagnosis checklists for the building exterior & interior
How to study building & site history when diagnosing the cause of peeling, flaking, or other paint failures
Basic indications of failing paint on a building
An encyclopedia of common painting mistakes that lead to early paint failure on buildings
An encyclopedia of types of paint failures on buildings & a detailed dictionary of paint terms & paint failure terms
Paint laboratory procedures for analyzing samples of failed paint from buildings
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This article series discusses 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.
The examples use building exterior paint failures (and remedies), but many interior paint failures are similar
their origin and cure, including general information provided
by some paint manufacturers, home improvement suppliers, and by National Forest Products Laboratory experts.
Paint sample analysis 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 historical information
Paint analysis for historical information: Microscopic and microchemical analysis of small samples of paint from a building interior or exterior can provide key historical information: the colors, types, and numbers of layers of paint used.
The New York Times reported (Feb 2010) an excellent example of this service: renovators of New York City cast-iron loft buildings dating from 1873 used paint chip analysis to identify the original colors of paint used on buildings as well as the history, sequence, and colors of 13 layers of paint.
Our paint lab photo (left) shows varying thickness of layers of white paint from a more modern building surface.
Paint analysis for paint failure diagnosis
Paint analysis for paint failure diagnosis: Using similar methods, the diagnosis and cure of paint failure on
buildings, particularly on wood siding and trim, is quite possible if there
is a careful and thorough inspection of the building, its history, its surfaces, and the actual points of paint
failure. It is diagnostic to compare the same coating on the same type of surface at different
locations on a building and in areas of failed and not-failed paint.
Our lab photo (left) shows four layers of paint, with a paint blister in the topmost layer. Paint blistering is discussed at PAINTING in SUN or WIND (thermal blistering). Distinguishing among types of paint blistering is discussed and illustrated at PAINT FAILURE ANALYSIS LAB PHOTOS
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 MOLD TEST KITS for DIY MOLD 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
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 author (at rear) and Art Cady preparing surfaces for painting.
"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.
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.
PAINT FAILURE CHECKLIST: EXTERIOR CLUES - Exterior Observations Related to Paint Failures
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.
Paint failure type: adhesion failures, cracks, stains, peeling, sagging, etc - this is a long list for which a paint vocabulary is useful. See PAINT FAILURE DICTIONARY. Naming the type of paint failure correctly is critical in diagnosing the cause of paint failure on a building or on an artifact or art work.
Paint failure pattern variations, such as by building location, exposure, weather exposure, surface type, wall field, trim, columns,
paint failures on horizontal surfaces vs. frequency of paint failures on vertical surfaces, paint failure
depth, type of peeling, alligatoring, checking or cracking,, or blistering or chalking. Hairline cracks in painted stucco surfaces that appear only in some building areas - see PAINT on STUCCCO, FAILURES
Appearance of surfaces from which paint has separated: mill gloss, chalking, old paint, wood fibers, moisture push. Blotching, white stains in painted stucco that appear only in some building areas - see PAINT on STUCCCO, FAILURES.
Mapping of failed and not-failed paint on various building areas, overlaid on the above list of possible causes.
Sun/shade/rain/wind/mechanical-damage exposure of the building surfaces
Surface drainage control
Roof runoff control
Evidence of paint or caulk-created moisture traps such as paint-sealed lap joints at heavily-painted wood clapboards.
Other site water/moisture sources, dominant direction of wind-blown rain and snow
Paint chip information (wood fibers, prior paint layers, mold, or debris present or absent on back of paint chips) - examined in the field by simple magnification, and examined in the paint lab using high power microscopy and paint layer sectioning can provide rapid, inexpensive, and conclusive paint failure diagnostic aid. See PAINT LAB SAMPLE PREPARATION and see Paint Failure Case Photographs-LAB.
Thickness of coating materials, number of paint layers, and identification of the layer which appears to be
separating. Collect painted sample materials or paint chips which will permit measurement of the dry film paint thickness (DFT) which
can be compared with the required wet film thickness (WFT) by calculation using the percentage of volume solids in the paint. See PAINT LAB SAMPLE PREPARATION.
Paint thinners: what thinners were allowed, in what quantities, and what thinners may actually have been used? Compare the quantity
of paint invoiced to the job with the coverage rating per gallon or liter of the paint. See paint thickness notes above.
Information about insulation, ventilation, vapor retarders, water and air barriers used on and in the building exterior walls. See VENTILATION in BUILDINGS.
Signs of exterior mold (misnamed "mildew:") on building surfaces on the
exposed surfaces, between paint layers, between the building surface and the failing or other paint coatings. Mildew is a sub-class of molds that grow on living plants (grapes, for example). See MOLD DETECTION & INSPECTION GUIDE and MOLD TEST KITS for DIY MOLD TESTS
Paint cans which held the current and prior paint used on building surfaces: for recording of the manufacturer or "paint brand", lot number,
tinting information, date of manufacture, and the producer's storage, application, thinning, area coverage rating, % volume solids,
recommended application thickness, and other technical information. Documenting the paints used on a building may discover incompatible coatings.
Paint and thinner MSDS sheets, if they are available; usually you can find these documents online from the manufacturer.
Water: evidence of water infiltration into building cavities, such as ice dam leaks into walls, leaks at windows, or general indoor
moisture and humidity levels and history, such as a history of wet basements, crawl spaces, attics, or specific building areas or rooms. Many paint failures are highly likely to be mapped to specifc locations of elevated moisture or actual building leaks. See STUCCO PAINT FAILURES for examples. See VENTILATION in BUILDINGS as well as WATER ENTRY in BUILDINGS and see VAPOR BARRIERS & CONDENSATION in BUILDINGS.
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Additional technical contributors & reference sources for this article are listed below.
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Paint and Surface Coatings, Theory and Practice, R. Lambourne & T.A. Strivens, Ed., Woodhead Publishing Ltd., William Andrew Publishing, 1999 ISBN 1-85573-348 X & 1-884207-73-1 [This is perhaps the leading reference on modern paints and coatings, but is a difficult text to obtain, and is a bit short on field investigation methods - DF]
Analysis of Modern Paints, Thomas J.S. Learner, Research in Conservation, 2004 ISBN 0-89236-779-2 [Chemistry of modern paints, overview of analytical methods, pyrolysis-gas chromatography signatures of basic modern paints and their constituents, Fourier transform infrared spectroscopy for paint analysis, direct temperature-resolved mass spectrometry, and analysis in practice - technical reference useful for forensic paint science, focused on art works -DF]
Seeing Through Paintings, Physical Examination in Art Historical Studies, Andrea Kirsh, Rustin S. Levenson, Materials in Fine Arts, 2000 ISBN 99-051835 [ forensic science, technical reference, focused on art works - DF]
Paint Handbook: testing, selection, application, troubleshooting, surface preparation, etc., Guy E. Weismantel, Ed., McGraw Hill Book Company, 1981 [Excellent but a bit obsolete paint theory and practice, also a bit light on field investigation methods, out of print, available used-DF]
Art, Biology, and Conservation: Biodeterioration in Works of Art, RObert J. Koestler et als. Eds., Metropolitan Museum of Art, 2003, ISBN 1-58839-107-8
Building Pathology, Deterioration, Diagnostics, and Intervention, Samuel Y. Harris, P.E., AIA, Esq., ISBN 0-471-33172-4, John Wiley & Sons, 2001 [General building science-DF]
Understanding Ventilation, John Bower, The Healthy House Institute, ISBN 0-9637156-5-8, 1995 [General building science-DF]
Dampness in Buildings, Diagnosis, Treatment, Instruments, T.A. Oxley & E.G. Gobert, ISBN 0-408-01463-6, Butterworths, 1983-1987 [General building science-DF]
"Moisture Control in Buildings: Putting Building Science in Green Building," Alex Wilson, Environmental Building News, Vol. 12. No. 5. [Good tutorial, "Moisture 101" outlining the physics of moisture movement in buildings and a good but incomplete list of general suggestions for moisture control - inadequate attention given to exterior conditions such as roof and surface drainage defects which are among the most-common sources of building moisture and water entry.--DJF]
"Peeling Back Paint Layers For a Glimpse Into the Past," James Barron, The New York Times, 25 Feb 2010, p. A26
"Staining and Microbiological Infestation of Acrylic Paintings on Hardboard", Ulrik Runeberg, Conservator (Dipl. Rest./M.A.), Museo de Arte Contemporáneo de Puerto Rico, San Juan Presented,April 2007 conference in Richmond Virginia, sponsored by the AIC (American Institute for Conservation), this paper discussed the staining and microbial infestation of acrylic paintings on hardboard. - private correspondence, ER <->DF 12 September 2006. The following quotation is from the paper's abstract:
"Hardboard served as a common and popular support for many modern paintings that were carried out from the mid - 1920’s, and still is used occasionally in contemporary art. Many artists rejected hardboard as an inferior industrial construction material of low aesthetical value, whereas others considered the processed and compressed wood fiber boards to be a stable, light and economic alternative to solid wood panels and other rigid supports.
"From the conservator’s critical point of view, the many disadvantages of this type of support include: high acidity, hygroscope characteristics, tendency of ‘off-gassing’, (>tendency of) warping, occasional flaking of painting material in the case of tempered hardboard. The deterioration of paintings on hardboard depends on a number of factors including: the quality of the hardboard, prevailing storage conditions, and the preparation of the support by the artist. While there are many paintings on hardboard that are in very good condition, this paper will focus on those paintings that are heavily deteriorated and damaged.
"A very characteristic damage found on porous painting layers such as acrylic colour on hardboard, is the formation of stains. Generally, those stains are described without any differentiation as ‘fox-spots’. The examination of various paintings concerned led to the conclusion, that there exist different kinds of stains that need to be discriminated against each other, to ensure an appropriate conservation and restoration treatment.
"This paper aims to characterize and differentiate the stains, and will provide preventive and practical treatment proposals for the conservation and restoration of affected paintings. Questions such as ‘What are the stains composed of?’ and ‘Which may be the causes?’ will be addressed. Stains may consist of a variety of contents, such as: Ligneous residues, fungal infestation, bacterial activity, a combination of microbial and support induced discolouration [SID], a ‘symbiotic relation’ of ‘SID’ and fungal infestation, or the blooming of ingredients from the original painting materials. A range of microscopic analysis of the actual microbiological infestation of selected samples will be provided. The paintings that were examined, sampled and treated, are part of the Puerto Rican heritage, and were all kept in excessive humid tropical conditions, before they entered the Conservation Department of the Museum of Contemporary Art in Puerto Rico.
"Conservation treatment options of stained paintings on hardboard will be discussed. A high level of acidity (caused from SID and/or micro-organisms) may require measures of reduction, disinfection and neutralization. Treatment methods that reduce the ligneous stains and residues of micro-organisms, and neutralize affected areas in painting layers include stain removal through the application of soaking compresses (poultices), and de-acidification through alkaline material.
"Other aspects of deterioration, that do not have to do directly with the formation of stains, but also are typical for hardboard as painting support, will be mentioned briefly." - U.R.
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