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Simple Sealant Overview

Aerospace sealants come in all shapes and sizes, and is complicated further by the different grades, cure times and specifications available. At Silmid, we are here to help, and below you will find a simple guide for selecting the right sealant.

Breakdown of Description

Below you will see a selection of products available on www.silmid.com, broken down into their specific characteristics:

PPG PR1440 B-1/2 150ml Semkit

3M AC-350 B-2 1USQ Kit

Naftoseal MC-650 Class B1 130ml Techkit-130


While these products may seem confusing, they can be easily understood following the below key:

Brand – The manufacturer who makes the specific sealant.

Product Number – This is the manufacturer’s name for the specific sealant product being used.

Class – This denotes the consistency of the product, and therefore the specific applications it should be used for.

Application Time – The length of time that the sealant is workable before curing.

Size – The volume of product contained in each pack

Package Type – the type of packaging will determine the potential applications and mixing required

 We will now look at some of these more closely.


Sealant Class

Sealants can generally be classified into 3 classes – A, B and C.

A – Brush application, generally used on fasteners
B – Thicker consistency, used for fillet and injection seals
C – Thinner than Class B, used for fay sealing

Sealant Application Time

Different application times are important as the nature of the work being carried out will vary depending on application. Where there is a large surface to be covered, a longer application time is necessary to ensure that the first product applied does not cure before the application work has been completed. Shorter application times are essential for time critical work, where the seal needs to be almost immediate.

Packaging Types

The packaging type will generally be concerned with two variables – volume of product required and the mixing process being used. Small volumes, for applications in multiple areas or by multiple users, are packaged into cartridge systems referred to as Techkits (manufactured by Techcon and generally used by 3M and Naftoseal) or Semkits (manufactured by Semco and used by PPG). These contain both the base and accelerator in one pack, and are mixed (either by hand or with the use of a mixing machine) using a piston rod sold as part of the kit.

For larger applications, or where a different mixing process is used, these products are supplied in separate tins (base and accelerator separate). These require closer attention to mixing ratios, as well as other application equipment including mixing sticks and dishes to hold the material).

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