Photograph of  peeling paint on a building exterior - can you diagnose this failure by eye? Paint Analysis - Peeling Paint? How to Diagnose, Correct, & Prevent Paint Failure on buildings

  • PAINT FALURE, DIAGNOSIS, CURE, PREVENTION - home - CONTENTS: 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
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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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Paint analysis for historical information

Paint job preparation (C) Daniel Friedman - by Daniel Friedman

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.

[Click to enlarge any image]

[Photo at left, the author & Arthur Cady painting a home on Parker Avenue, Poughkeepsie, NY]

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.

Paint lab Photograph of sample of failed paintWe 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 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

Photo of paint solvent blistering, edge view in laboratory

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

Hardboard fiber staining on Art Work (C) U Runeberg D Friedman Alkyd Oil Flake Investigation on Art Work (C) U Runeberg D Friedman

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

Paint job preparation (C) Daniel FriedmanAlso 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."

Poor prep trim paint job (C) Daniel Friedman"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.

PAINT FAILURE CHECKLIST: EXTERIOR CLUES - Exterior Observations Related to Paint Failures

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.

    Photo of the author, with Art Cady and Net, setting up a house painting job, Poughkeepsie NY ca 1988
  • Dictionary of types of paint failuresand problems, and other painting terms - see PAINT FAILURE DICTIONARY
  • 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.
  • Pattern, location, and type(s) of paint failure found
  • 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 -

  • 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 STUCCO, 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.


Poor prep trim paint job (C) Daniel Friedman
  • 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.


    Our photo (left) shows the condition of a nearly brand-new paint job on an older home in Poughkeepsie, NY. We noticed that old paint was left on the surface with no feathering of the edges of the few spots where paint had been removed or had fallen off before the paint job.

    We noticed also that the painter tried to "seal" the loose paint by globbing on plenty of new paint - see that drip running down the trim board?

    Finally, we noticed that this new paint job was already failing - the split in the paint visible in the lower portion of the photograph.

    Although the building owner told us that this paint job was "guaranteed" by the painter, these observations made us nervous. How many times will the owner be able to call the painter back to "touch up" these annual failures in the paint job before the painter gets tired of these unpaid visits and informs the owner that now the paint failure is "normal aging"?

    This paint job will have a shorter life than if the surface had been stripped, but then the painter (and owner who was selling his home) avoided a much higher cost of stripping lead-containing paint from an older building.
  • 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.

  • Rust stains on buildings - see Rust Stains on Shingles
  • 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).


  • Samples of paint used at the building, including liquid samples of primer and top coat, for possible further testing.

  • 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 specific locations of elevated moisture or actual building leaks.

    See STUCCO PAINT FAILURES for examples.

    See VENTILATION in BUILDINGS as well as

    and see VAPOR BARRIERS & CONDENSATION in buildings.

Quotes in the opening text of this document are from the encyclopedic but not quite complete paint website: PPG Exterior Failures

Continue reading at PAINT FAILURE ANALYSIS

See PAINT FAILURE INDICATORS for more detail when invasive inspecting is permitted.

Our PAINT & STAIN LIFE CHART gives typical life expectancies of building exterior coatings on different types of wood surfaces. Also see LEAD POISONING HAZARDS GUIDE.

Suggested citation for this web page

PAINT FALURE, DIAGNOSIS, CURE, PREVENTION at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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