$WACKER<sup>®</sup> 138

WACKER®138 is a one-part, acid-curing, high-modulus silicone sealant for glazing and industrial applications.

WACKER ®138 cures at room temperature under the action of atmospheric moisture to give a permanently flexible silicone rubber.


•  Non-sag

•  Ready gunnability at low (+5°C) and high (+40°C) temperatures

•  Low shrinkage during vulcanization

•  Flexible at low (-40°C) and high temperatures (+180°C)

•  Rapid curing,quick skin forming and tack-free time

•  Long shelf life

•  Slovent-free  

•  High modulus

•  Excellent adhesion with glass,vitrified surfaces,ceramic tiles,many plastics and most paints




•   Glass and windows construction

•   Sealing of joints between glazing and supporting structure (frame, transoms, mullions)


Restrictions on use


WACKER® 138 should not be used on substrates such as marble, concrete, fibrous cement and mortar, as the product releases acetic acid during vulcanization.

WACKER® 138 should not be used in contact with metals such as lead, copper, brass, or zinc due to corrosion.

WACKER® 138 may be discolored in contact with some organic elastomers, e.g., EPDM, APTK and neoprene.

WACKER® 138 is not recommended for sealing of aquaria, please use our ELASTOSILÒ 121.

WACKER® 138 is not recommended for use on natural stone, such as marble, granite, quartzite, as it can cause staining.

WACKER® 138 is not recommended for structural glazing bonding.




The substrate areas that will be in contact with the sealant must be clean, dry and free of all loose material, dust, dirt, rust, oil and other contaminants. Non-porous substrates should be cleaned with a solvent and a clean, lint-free, cotton cloth. Wipe dry immediately with another such cloth before the solvent evaporates from the surface.




WACKER® 138 exhibits excellent primerless adhesion to most non-porous siliceous material, e.g., glass, tiles, ceramics, enamel, glazed tiles and clinker; impregnated, varnished or painted wood; and some plastics.

Users must carry out their own tests due to the great variety of substances.

The adhesion can be improved in many cases by pretreatment of the substrates with a primer.


WACKER®138 is usually supplied in standard size cartridges that fit all standard caulking guns.


The 'Best use before end' date of each batch is shown on the product label.

Storage beyond the date specified on the label does not necessarily mean that the product is no longer usable. In this case however, the properties required for the intended use must be checked for quality assurance reasons.

Sales and support

Wacker Chemical Corporation
3301 Sutton Road
Adrian, MI 49221-9397
United States
+1  888  922-5374 (Phone)

How can we help you?

  • Do you need help in choosing a product or do you require technical support? If so, please contact our experts.
Ask a question


WACKER has a global network of specialist distributors at its disposal. Please select an application so that we can suggest suitable contacts.

Brenntag North America
1 Cragwood Road Suite 302
812021 South Plainfield
1  6109266100 (Phone)
1 6109163782  (Fax)
Contact distributor Website


My media

My favorites

My products