An Introduction to Sealers Across Restoration


“Sealers” represents a set of tools for the restoration professional.  There is no sealer that does all the restorer needs.  These are paint-like coatings that are formulated explicitly for one or more functions in the restoration process.  Most often, sealers are useful when there is something that needs to be contained with a durable or impervious barrier between that contained substance, and the well-being of the occupant.  There are multiple roles in which sealers are employed.  Restoration contractors commonly use sealers as part of work involving structural fire/smoke and wildfire.  There are also uses involving mold remediation, biohazard and the control of odors.  Additionally, in the abatement of asbestos or lead-based paint, licensed abatement contractors use specifically tested and approved encapsulation coatings, often referred to as sealers.  Each of these uses of a “sealer” require certain performance capabilities.  Much grief and frustration has been caused by inexperienced contractors spraying willy-nilly some asbestos lockdown into smoked spaces because they shopped their distributor for the least expensive “encapsulant”.   One of the first things a restorer needs to know is there is no universal sealer.  Just as the complete toolbox has a variety of wrenches, drivers, and bits; the competent restorer recognizes there are very specific sealers for different projects.  Further, the wise restorer doesn’t have to know the capability and compliance details of every type of sealer, only where and who has that information. 

Sealers for Fire/Wildfire Purpose

For this discussion, the focus is on sealers in the context of restoration after structural fire or wildfire.  

When we think of sealers, we usually expect their use toward the end of a project.  Across all the restoration disciplines, a common principle is the removal of undesirable and/or unhealthy contaminants that resulted from a chronic or catastrophic development in our built environment.  The restoration professional is engaged to bring that environment back to the intended liveable state, also expressed as the pre-loss condition.   A sealer is generally not needed if cleaning is effective in removing all the PICs.  

In the aftermath of structural fire and wildfire, it is not always possible to remove all the damage, and there can often be residual contamination despite best efforts and methods.  For these projects, sealers are frequently used for one or more purposes: 

  • block/inhibiting transmission of future odors
  • stain blocking (bleed-thru of heat and smoked discoloration, as well as wood resin (tannin) bleed-thru)
  • lockdown of residuals after all other restoration processes

On some projects, cleaning isn’t going to be enough.  Sometimes from the outset, using professional judgment, the restorer advises the MIPs that best-possible cleaning followed by a sealer is advisable.  This is a “Clean for Paint” (also “Prepare for Paint”) bid or specification.  This is a very helpful term with a long history of use by fire/smoke mavens.  Simply put, Clean for Paint is removal of fire/smoke residues to a degree sufficient for the proper application of sealer.


So, why don’t we follow the examples of the asbestos and lead paint professionals, and instead of sealer, we could rely exclusively on the words encapsulant or encapsulation for otherwise immovable combustion residuals.  Those words have long been in several guidelines, scopes and lit on fire/smoke damage, and even appear in the product names of some professional smoke odor sealer products.  The problem with using encapsulation becomes rapidly apparent as the lines continue to blur, and formerly abatement-dominant firms develop more restoration work; and meanwhile, restoration professionals develop abatement capacity because they see downsides of subcontracting asbestos and lead.  

For the abatement world, to encapsulate asbestos and lead, the process involves leaving as much of the offending material in place, removing only what is too fragile (friable being the asbestos term), and then overcoat with a permanent barrier coating.  Asbestos and lead paint are immobile, inert, and inanimate.  It is possible to prep and paint with an approved product and permanently isolate the potential hazard by eliminating any pathway of future exposure.  That is, in fact, how encapsulate and encapsulation are legally defined.  In the abatement world of licensed abatement professionals, and work practice standards in federal and state regulation: management-in-place permanently. 

Even so, this permanence does call for oversight and regular maintenance.   This is a big reason why it should be noted that most property owners choose to have asbestos and lead removed instead.  A hazard that is gone, equals a hazard that cannot pose a future concern if/when containment is violated. 

ALARA and Contaminants

The idea of painting over undesirable contaminants is justifiably anathema to the professionals involved in restoration, at least to those considered prudent and competent.  Among the only universal principles is to remove contamination insofar as possible.  Compared to the relatively passive ACM & Pb, the restorer is used to stuff more disgusting, complex, and dangerous.  Since we are attempting to achieve a pre-loss condition, the dynamics of restoration slant away from encapsulation.  Aesthetic comfort and economic function may be difficult to predict with contamination that can continue to corrode (causing the barrier to fall away, as well as ongoing substrate deterioration), and which may off-gas indefinitely.  

Then there are the concerns which industry-wide are becoming increasingly acute about health risks associated with byproducts or substances found post-event.  Our awareness seems to grow year-over-year that there are concerning contaminants among typical products of incomplete combustion (PICs).  From interviews with users and manufacturers, here is a compiled but not comprehensive list: 

  • Benzene
  • Isocyanates
  • PCBs
  • PAHs
  • Dioxins
  • Furans/Dibenzofurans
  • Aldehydes, Formaldehyde
  • Inhalable fibers: asbestos, ceramic, mineral, carbon
  • Particulates, including metals (lead, cadmium, mercury).

To the shellshocked owner, this list of toxins and carcinogens is terrifying, and to them using a sealer after cleaning seems only logical.  It is important to note that for dioxins for example, there is no safe level established by EPA.  Consider this:  when the PVC in vinyl siding burns, one of the primary byproducts are dioxins.  

There are so many variables, and every fire project is unique, but what byproduct chemicals and compounds that can be found among soot and ash is simultaneously persuasive that as much of the PICs as possible must be removed; And, that there is benefit in a sealer to perform a post-cleaning, post-removal lockdown function to anchor trace residuals to surfaces.  

For use in training and client communication, there is an enlightening acronym from the nuclear decommissioning industry that often resonates: ALARA.  Developed for safety for those engaged in nuclear weaponry or civilian energy as far back as the 1950s, this term is As Low As Reasonably Achievable.  ALARA communicates safety, an intent to reach for the highest bar in hazard elimination, but also that there are challenges and constraints we can’t ignore.  The concept is well-suited for fire/smoke damage restoration – easily understood and retained.  

Sealer Types

A variety of specialty fire and smoke damage sealers are manufactured (e.g., oil based, water based, shellac based, and synthetic shellac based).  However, the performance may vary based on site conditions and applications.  Considerations must be made as to the surface and intent for using a particular type of sealer prior to the application including but not limited to: 

  • Surface condition – Unstable surfaces, including severe thermal or direct combustion damage, are usually better removed, rather than attempted control using a sealer.
  • Degree of probable surface adhesion – Surfaces must be dry, and to the degree possible, clean and clear of untreated combustion particles, rust (untreated rust will continue to degrade metal under the sealer coating), grease, wax, oil, and mold.
  • Appearance – Application of sealers on unfinished building surfaces permanently alters the visual appearance.

The following table identifies four basic types of sealers used in fire restoration along with their basic  advantages, disadvantages, and some notable information.

[for the spatial purposes of this chart, the abbreviation SOS for Smoke Odor Sealers will be used when referring to these products as a group]

Sealer Best Practices for use in Fire/Smoke Damage Restoration:

Over decades, professional fire/smoke damage restorers and sealer manufacturers have together accumulated a storehouse of knowledge that the entire industry benefits from today.  While in this eBook section format there is only so much bandwidth, the following are invaluable tips, tricks, traps, and more – including some seldom if ever seen in standards, guidelines, or scopes of work.  In alphabetical order by topic:   

  • Char
    • Heavily charred wood can seem daunting and irredeemable, however often the char has formed a protective layer underneath which the wood is cleanable but probably will need a sealer to prevent odor release overtime. Sealers should never be applied over charred wood that has not been abraded to remove as much of that black “scab” charcoal as possible. After mechanical cleaning, and then a liquid odor counteracted or desorbent, then a sealer can finish the restoration process.
  • Colors
    • Sealers are commonly tinted white for the purposes of application verification.
    • Woodtone:  Many sealers are premade or tintable in wood tones to make them less obvious as to their intended purpose to occupants.  Two of the major SOS water-based product manufacturers maintain inventory of white, clear, and woodtone.
    • Photo courtesy of Jim Anders, ICP Group

      Clear Sealers: Some sealers are tinted for application purposes (user can see where they are going), but dry clear. Use of clear sealers can be very useful, but on those surfaces that have sustained visual fire or smoke damage, when the project is over, that damage will still be visible.  It is advisable to have the MIPs acknowledge that will be the case in writing before application.

      • Close inspection is required for verification of thorough application of clear sealers. Many sealers have a sheen that is observable when a bright light is shone upon coated surfaces at an angle.  This evaluation practice reveals areas that have received adequate coating versus those where application did not achieve a contiguous film.
    • Regardless of opaque (pigmented) or clear, all film-forming sealers should be able to hold back odors as well as stain bleedthru or wicking.
    • Even clear sealers will change the look of surfaces.  For clear, sometimes this is a wet look plus the gloss.  Ideally, have samples in your kit on wood for white, clear, and woodtone that can be shown to the MIPs.  Get their written sign off that they understand the appearance is going to change long before the first pail of sealer is sprayed.

      Photo courtesy of Joe Cirone, Sentinel

  • Contiguous Coverage
    • Sealers must be applied in sufficient quantities and from varying vantage points so that all contaminated surfaces are uniformly addressed.
    • Failure to provide adequate coverage will result in failure to inhibit smoke odor transmission.
    • Avoid application shadows where airless spray applications may not reach all surfaces unless the applicator changes position.  For example, an applicator standing at one central point in an attic cannot treat surfaces in the leeward side from the origin of the sprayed coating.  Shadowing errors are common sources of odor complaints, and preventable with applicator training and allocating sufficient time for the work.
  •  HVAC & Smoke/Odor Sealers
    • If only because HVAC&R (Heating, Ventilation and Air-Conditioning/Refrigeration) systems are inherently difficult to clean due to access, the use of sealers is often considered when air conveyance systems are contaminated with post-combustion residues.
      • At the time of this writing, an IICRC standard for assessment of HVAC after a “water, fire, or mold damage event” is in public review, and publication appears likely in 2023.  Restorers will be well advised to reference this document, including for guidance regarding sealers.
    • Photo courtesy of Joe Cirone, Sentinel

      Wildfire impacted structures can be especially prone to HVAC contamination, due in large part to the continuing operation of air handling systems that introduces dessicated vegetation and conifer residues that can be very difficult to clean.  If air systems are not going to be replaced, then it is likely that a sealer will be needed because effective cleaning will be limited.

    • Testing Applicable to Sealers Used in HVAC systems:  Sealers that are to be used in air conveyance systems must meet the testing requirements of:
      • International Building Code (IBC)
      • ASHRAE 180 Standard Practice for Inspection and Maintenance of Commercial Building HVAC Systems (ANSI/ASHRAE/ACCA Approved),
      • National Fire Protection Association (NFPA-Protocol 90A/90B) and
      • State and Federal building code requirements.
  • Insulation, Drywall Paneling
    • Do not install these replacement materials until the odor sealer has adequately dried.  Odor sealers not permitted to dry per manufacturer instructions may not set-up as a film capable of containing fire odor.
  • Permeability
    • As discussed in the chart above, one of the most important criteria when considering a sealer is the ability of the product to permit normal vapor transmission through critical building surfaces without creating condensation planes that can put moisture where it isn’tt supposed to be. In some buildings, the health of the structure is dependent on the ability for certain walls to breathe. While shellac and oil based products can stop future fire odor, as one of the chemists we interviewed said, like a stone wall, these products stop water vapor as well.
    • A common question since the permeable water based odor sealers were developed over the past decade is how a sealer allows water vapor to pass, but serves as a barrier to the molecules associated with smoke odor. There is no single answer. One manufacturer promotes their smart membrane as a pasta strainer that allows the water to pass through, but holds back the larger molecules associated with odor. Another manufacturer explains their mode of action similarly except it works because of the differential in mass or molecular weight, as opposed to size. Another example of the differing technology and science employed came from yet another company’s chemist as he described how they use a cationic binder (a positive charge) to repel odor molecules with a negative charge. This enhances the effectiveness of their smart membrane.  In short, research continues especially in the water-based odor sealers.
  • Post-Source Removal Job Walk (Or PRE/PRV Process)
    • Using a sealer before verification that adequate cleaning has been completed causes immense amounts of unnecessary static between restorer, adjuster, and every other party concerned. Obviously, a sealer will obscure visual inspection, and can get in the way if smoke odor has returned and now the source must be found.
    • Much like the well established processes for mold remediation or lead paint abatement, there is a pause during the process to verify that the cleaning and stabilization sections of the scope have been satisfied. When that is completed, then sealers can be applied.
  • Solids Content
    • Regardless of type or brand, always look at the Solids Content by Volume (as opposed to Solids Content by Weight.  This is information a reputable manufacturer won’t hesitate to provide, and a good indicator of general quality (but not explicitly special performance such as odor blocking).    To provide a benchmark, a solids content by volume of 40% or higher would qualify a SOS for professional consideration.
    • Want to sharpen your estimating and check against anyone who tells you their product will yield thousands of feet per gallon?  Common sense will tell you otherwise anyway, but with math you can know for certain how far your SOS will go (not including soaking in, corrugation and other variables.  The coverage obtained from any gallon of paint is dependent on its solids content by volume (VNV). Here is the math:
      • One gallon occupies a volume of 231 cubic inches or 0.1337 cubic feet.
      • If a gallon of paint contained 100% solids and if it could be applied without losses, the coverage obtained from one gallon at a film thickness of 1 mil (0.001, i.e. one-thousandth of an inch) would be 1604 square feet.
      • Normally, one-thousandth of an inch isn’t enough for a cotntiguous film, and as established, that is necessary for effective blocking of smoke and stains.  Assuming 3 mils on a smooth surface is necessary for the dry film, take the figure above (the theoretical coverage per gallon), and divide it by 3 to get the ideal coverage to expect from that gallon of SOS.
      • From there, modify your calculations with overage, spillage, waste, product left in the sprayer, etc.
  • Universal Sealers:
    • There is no universal sealer that can be used in all types of restoration work, such as fire/smoke, mold, and biohazard.  Similarly, there is no truly effective stain-blocking primer.  Any primer advertised as good at all priming against bleeding and wicking (such as rust and tannin), isn’t probably especially good at any of these tasks.
    • Sealers are not uniformly effective. There is a certain amount of research and experimentation that the restorer can do before selecting a formulation and manufacture they trust. However, even then the restorer always has to keep in mind unique projects may require a different tool than the sealer they usually use.
    • The most reliable way to maximize the success of your sealer is to maximize the effectiveness of your cleaning and odor neutralization.
  •    Voids. Gaps
    • Large gaps in building construction may require application of caulk and/or expandable foam, particularly in heavy and pressure driven contamination of framing (e.g., attic systems, wooden floor joist systems, wall framing and residential staircases/stringers) prior to sealing.
    • Uncleanable Voids & Gaps:  Places in building construction where components come together can accumulate combustion residue that may release future odor.  Construction juxtapositions such as along sill plates or sistered members can be very difficult to clean. Users attempt to force continuous coverage of a sealer into and onto such surfaces by attempting to fill the void and then bridging with the coating.  This can lead to future odor for two reasons:
      • Uncured Sealer:  Wet film may be propelled such that some penetration of sealer into a gap or void is achieved, but without normal access to the atmosphere, the sealer may not cure into a dry film, or even dry at all.  Manufacturers formulate the ability to hold back odor based on a properly cured film.  Wet, semi-dry, or sealers dried under abnormal conditions simply may not work.
      • The Meniscus Trap:  A meniscus in this context is a concave wet coating film suspended by surface tension across a gap or void.  While a wet meniscus forms temporarily seeming like coverage has been achieved, coatings contract as they dry.  The meniscus retreats and then ruptures, re-exposing surfaces that can potentially release odor.  Restorers fall into this trap when not looking for it during end of project walkthrus.
    • Avoid silicone caulks.  Those might repel the odor sealer applied next, especially if it is water-based.

Contributions – Sources and Authority

Sources include written documents and interviews with users and manufacturers.  There are three main documents, with primary being the RIA Guidelines for Fire and Smoke Damage Repair.   These Guidelines have been the fire/smoke backbone training document for decades.  Written by the esteemed Martin King, and reviewed by more than 300 professionals, there are numerous significant statements regarding sealers for the restorer to be aware of.    The other two documents are the two standards respectively for structure fire and wildfire developed by the Institute for Inspection, Cleaning and Restoration Certification (IICRC):

  • BSR/IICRC S700 Standard for Professional Fire and Smoke Damage Restoration
  • BSR/IICRC S760 Standard for Professional Wildfire Investigations and Restoration of Impacts to Structures, Systems, and Contents

At the time of this writing, what will be the first edition of each standard is in public review.  And as is to be expected for the initial release on high-interest topics, both have several hundred public review comments to be resolved before acceptance by the international standards vetting authorities, and then publication.  Since each inevitably will become official and in-force, when it comes to sealers it is worthwhile to look at both standards. Assuming changes are minor, regarding sealers, the restorer needs to recognize the documents average two dozen mentions of sealers/coatings, and as drafted both standards provide sections specifically addressing sealers for their type of fire/smoke restoration.  The fundamentals herein are compatible with all three consulted sources: the Guidelines, as well as both 2023 IICRC standards.

Five of the most popular and restoration-specific manufacturers were interviewed, as well as some users and influencers.  By restoration-specific, the criteria was producers of popular sealers that are specifically formulated for odor reduction and stain-blocking, and primarily produced for fire/smoke-structural/wildfire restoration.   Manufacturers of paint products incidentally used in restoration, even in some volume, were not consulted, at least this time around.  Certainly this is author’s preference to maximize inclusion, but preparation time and bandwidth is always limited.  In conducting interviews, manufacturer input was gathered from written Q&A, as well as 1-2 hour live discussions with 4 of the 5 (and the fifth was approached late in data gathering).  All 4 interviews included senior coatings chemists, and their contributions were invaluable.


1. –. “Are You Leaving Time and Money on the Table? [Asbestos].” Cleaning & Restoration, Feb. 2022,

—. “Asbestos Abatement Best Practices.”, C&R Magazine, Jan. 2022, Accessed 11 July 2022.

—. “Asbestos Encapsulation: A Coatings Compendium.” Restoration & Remediation, 29 Aug. 2014,

— Encapsulating Lead Paint Project: Victorian Restoration., 2 June 2007,, disc Episode 11, Part 4. Accessed 11 July 2022. Recorded Television Broadcast.

—. “Build Business and Serve Customers with Lead Paint Encapsulation.” The Paint Dealer, 1 Mar. 1998.

2. Other terms associated with sealers include:  Chemical Barriers, Surface Modification.

3. S590 – IICRC  Tom Yacobellis, Joshua Woolen (Chair & VC, 1st Ed.)

4. Similar to the preceding bullet, there is an IICRC standard in public review at the time of this writing that concerns restoration after wildfires.  See Brad Kovar, Pat Moffett (Chair & VC, 1st Ed.).  Presuming it is not eliminated during public review (unlikely), there is an extensive amount of information regarding HVAC including sealers.  Refer to Section 12 (designated in public review document, may change) Restoration of Wildfire Impacted HVAC Systems for additional information.  Tom Yacobellis and the IICRC S590 committee were instrumental in developing this section. Restoration of Wildfire Impacted HVAC Systems for additional information.

5. King, M. L., Kovar, B. The Journal of Cleaning, Restoration & Inspection. 

The Use of Primers and Sealers After Fire and Smoke Damage Vol. 3 Issue 1 February 2016


7. Bran Lynch, John Pletcher (Chair & VC, 1st Ed.)

8. Brad Kovar, Pat Moffett (Chair & VC, 1st Ed.)

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Cole W.D. Stanton

As a Senior Consultant for the new Restoration Crosscheck consulting collaborative, Cole Stanton continues to build on three decades in Building Materials & Sciences.

He is the go-to authority for chemistry-driven tools and methods used in abatement and restoration.  His client-base includes restorers and consultants that want team training and/or SOP-”Load List review in proper use and management for antimicrobials, fungicidal & mold-resistant coatings, specialty cleaning technology, the encapsulation of asbestos and lead paint, and more.  Cole produces architectural specifications, expert services, industry articles and innovative solutions for asbestos, lead-based paint, mold, biohazard, structural fire, and wildfire challenges.  He is an approved IICRC Continuing Education instructor, and an active or recent contributor to the development and coordination of industry standards, including: ASTM D22.12 Lead Exposure subcommittee, AIHA Wildfire section co-leader for revision initiative of RedBook2, RIA/IAQA FS#2 Structural Fire, and IICRC: S520 Mold Remediation, IICRC S540 Biohazard, IICRC S760 Wildfire Assessment & Restoration, and IICRC S500 Water Damage Restoration. He also serves IICRC as Vice-Chair of the Continuing Education Committee.

Cole is a graduate of Boston College with a degree in Political Science and resides with his family outside Boston.

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