Knowledge Base

    Choosing a Sealant

    • What information will help me choose the right sealant?

      You could use a specification or product name which is dictated by the aircraft’s maintenance manual or QPL, your head of maintenance, or your contract with your customer.

      You can consider the price, the amount of time needed to apply the sealant, or how quickly the sealants need to cure.

    • What is a “primerless” sealant?

      Primerless sealant is sealant that can be applied to the substrate material without the application of a primer beforehand.

      For example, Dapco 2100 firewall sealant and Dapco 2200 firewall sealant are primerless, requiring no primer. Dapco 18-4F is a firewall that requires the primer Dapco 1-100.

    Frequently Asked Questions


    • How is pricing determined?

      There are multiple variables determining product price, such as:
      Part name, type, class, or manufacturer
      Shelf life requirement
      Purchaser type: Distributor or end-user?
      Every quote is custom, created just for you and your specific needs.


    • What are some specific ways the aerospace industry gives back to the community?

      Check out these 5 non-profit organizations!

    • What are the key MRO tradeshows and conferences in the aerospace industry?

      -MRO Americas

      -MRO Europe

      -MRO BEER

      -MRO Middle East

      -MRO Asia-Pacific



    • What are the key PMA conferences?


    • What are the key sectors of the aerospace MRO industry?

      There are 4 key sectors:

      1. Airframe heavy maintenance
      2. Engine maintenance
      3. Line maintenance
      4. Component maintenance


    • Can I mix a semkit by hand?

      You can mix a semkit by hand, or you can use a semi-automatic or automatic semkit mixer to save time and fatigue.


    • How is pricing determined?

      There are multiple variables determining product price, such as:
      Part name, type, class, or manufacturer
      Shelf life requirement
      Purchaser type: Distributor or end-user?
      Every quote is custom, created just for you and your specific needs.

    Sealant Application

    • How do I pick an application tool?

      The class of the sealant your tooling will determine that. For instance, Class A sealants are a flowable (self-leveling) consistency, but Class B sealants are paste-like in consistency.

    • My sealant is curing, but it isn’t adhering properly. Why? What can I do to fix it?

      There are 3 common scenarios:

      1. A damp surface
      2. Contaminants on the surface
      3. Incompatible surface cleaners

      Here are some solutions we often offer our customers!

    • What tools can I use to apply sealant?

      Here’s a list of some of the tools you can use, categorized by the class of sealant:

      -Class A: Brush

      -Class B: Extrusion gun, putty knife, or spatula

      -Class C: Brush, extrusion gun, or spatula

      Read in detail.

    • Why is my sealant not curing?

      See below.

    Sealant Basics

    • How do I calculate the shelf life of a sealant?

      You use the start date, today’s date, and expiration date. Make it easy and use our shelf life calculator!

    • What do the numbers and letters in a part name mean?

      Great question! We get asked this a lot. Let’s take a look at WS8020RC B1/2.

      WS = the sealant manufacturer, in this case Royal/HB Fuller

      8020RC = the identifier chosen by Royal/HB Fuller. In this case, RC means rapid cure.

      B = The class of sealant which indicates its consistency.

      ½ = The amount of time you have to apply the sealant. This number is measured in hours, so ½ would equate to 30 minutes.

      Find more details.

    • What does PR stand for in PR-1422? Or WS in WS8032S?

      PR is the manufacturer’s acronym. It stands for PRC/PPG. Here are more acronyms for top sealant manufacturers and PMA sealants.

      WS – Royal Adhesives now HB Fuller

      NSL – NSL Aerospace PMA Sealants

      Dapco – D Aircraft now Solvay

      AC – 3M

      PR – PPG/PRC

      P/S – PPG/PRC

      CS – Flamemaster

    • What does shelf life mean?

      The purpose of shelf life is often misunderstood. It is not an indicator of the quality of the sealant. It is an indicator of the time left for the sealant to be used at its full efficacy.

      A sealant that has 5 days of shelf life left is of the same quality as a sealant with 100% shelf life.

    • What is the difference between sealant application time, tack free time, and cure time?

      Application time is the amount of time you have to work with or apply the sealant after it has been mixed or thawed, in the case of PMF.

      Tack free time is the necessary amount of time for the sealant’s surface to lose its stickiness while in the process of curing. 

      Cure time is the amount of time it takes for a sealant to reach its appropriate hardness.

    • What’s the difference between Class A, B, and C aerospace sealants?

      The difference is viscosity. Class A sealants have a self-leveling consistency. Class B sealants have a paste-like consistency. Class C sealants have a flowing consistency.

    • Why isn’t my sealant drying?

      It may not be thoroughly mixed. Read our suggestions here!

    Sealant Mixing

    • How do I mix a two-part polysulfide?

      You can do it by hand (see suggestions here) or use a mechanical mixer.

    • What are indicators that my two-part polysulfide may not be thoroughly mixed?

      1. Application period is a lot shorter than indicated: If you are using a machine mixer or a hand drill, you may be operating it at too high of a speed which can create internal heat and shorten your application time.
      2. You see streaks of color in the cartridge or container. (Learn more about the rule of thirds for kit mixing!)
      3. It’s not fully curing.
      4. It’s not adhering properly to the surface once cured.

    Sealant Removal


    • Can you do blind shipments?

      Yes! Just send us whatever documentation you want your customer to receive with the shipment, e.g. a packing slip, invoice, etc. Please clarify whether you need changes made to our labels such as removing our logo or company name. If you would like to provide your own labels, we are happy to use them, though we are not able to print them for you.

    • Do you drop ship?

      Yes, we do!

    • Do you ship overseas?

      Yes! Please be prepared to provide the account number for your preferred shipping method and to arrange pickup for any overseas shipment.

    • Do you ship worldwide?

      We do! You can learn more about our international sales and speak with our customer service team to meet any customs or shipping needs you have.


    • What does the AMS-S-8802 specification stand for? 

      Check out an excerpt from our AMS-S-8802 background page:

      “AMS-S-8802 standardizes the specifications for temperature-resistant, two-component synthetic rubber compounds of the polysulfide type. These are used for sealing and repairing integral fuel tanks and fuel cell cavities, for continuous service use from -65 to +250 °F (-54 to 121 °C). AMS S 8802 type 1 is a dichromate cured sealant. AMS-S-8802 type 2 is a manganese dioxide cured sealant. Within types 1 and 2 are three classes: A, B, and C.”

    • What does the MIL-PRF-81733 specification stand for?

      Check out this excerpt from our MIL-PRF-81733 resource:

      “MIL PRF 81733 standardizes the products for accelerated, room temperature curing synthetic rubber compounds. These materials protect metal components on weapons and aircraft systems by sealing and coating them. These sealants perform a critical role: they are an effective barrier against the common causes of corrosion on aluminum alloys or between dissimilar metals.”

    • What is a MIL spec?

      MIL spec stands for military specification. They are a part of the Department of Defence’s Standardization Program to “seek to limit variety in purchased items by stipulating certain design details.”

      Learn more about key aerospace military specifications like MIL-PRF-8516G, MIL-S-8802 (now AMS-S-8802), MIL-S-81733 (also MIL-PRF-81733), and more.

    • What is the difference between AMS specifications and MIL specifications?

      AMS specifications supersede MIL specifications as a result of the U.S. government’s Preparing Activities (PA) that released specifications and standards to Non Government Standards Bodies (NGSB), like SAE