Midwest Sealing Products is an authorized fabricator and distributor of Thermoseal gasket materials including their Klingersil line of compressed sheets. Following are the more popular Klingersil sheet materials:

Klingersil C-4201

This product uses a synthetic fiber with a nitrile binder and offers excellent resistance to oil and solvents.


Klingersil C-4300

This product is a general purpose sheet with synthetic fiber and nitrile binder which offers good chemical resistance and sealability.


Klingersil C-4401

This is the most popluar OEM sheet also using synthetic fiber with a nitrile binder, offering excellent sealability along with chemical resistance and good creep relaxation.


Klingersil C-4430

This is an excellent steam sheet using fiberglass and aramid fibers with a nitrile binder. C-4430 offers excellent chemical resistance and good creep relaxation.


Klingersil C-4433

This is Thermoseal’s ultimate steam sheet using fiberglass, aramid and inorganic fibers with a nitrile binder. It offers excellent creep relaxation and load bearing characteristics.


Klingersil C-4500

This product is made of carbon fiber with a nitrile binder. It can be used in high temperature and high internal pressure applications. C-4500 is a good steam sheet and is also suitable for a wide range of chemical applications.


Klingersil C-5400

C-5400 is a synthetic fiber with a neoprene binder that is chemically stable. Neoprene bound materials are often used in the refrigeration industry.


Klingersil C-6400

This product is made of synthetic fiber with an SBR binder and is a good steam sheet.


Kingersil C-7400

C-7400 uses a synthetic fiber with an EPDM binder and can be used in applications with moderate caustics and acids. It has good oil and swell characteristics with excellent aging properties and is good in light duty steam.


Kingersil C-8200

This product has no color added and is made of synthetic fiber with a Hypalon® Binder. It offers good acid and oil-fuel resistance and gas sealability.


Please contact us to discusss using Thermoseal gasketing products in your next application.

** The pressure/temperature graphs shown are the most current method of determining the suitability of a gasket material in a known environment. use the pressure and temperature graphs to select the most suitable material for your application.


  1. In area one, the gasket material is suitable using common installation practices subject to chemical compatibility.
  2. In area two, appropriate measures are necessary for installation of the gasket to ensure maximum performance. Please call for assistance.
  3. In area three, do not install gaskets in these applications.

these graphs were developed from testing Klinger materials. Do not use them for competitor’s materials since non-asbestos gasketing materials do not have service equivalents.

*Disclaimer: Midwest Sealing Products, Inc. believes that the information provided is a true and accurate description of the products listed. However, it is the responsibility of the user to test the product to determine performance, efficacy and safety.