• two-part, 1 : 1 mixing ratio
  • flowable
  • rapid heat curing
  • forms a highly transparent rubber on vulcanization

LUMISIL® 903 A/B is a silicone for transparent potting in the lighting and electronics industry.

All surfaces must be clean and free of contaminants that will inhibit the cure of LUMISIL® 903. Examples of inhibiting contaminants are sulfur containing materials, plasticizers, urethanes, amine containing materials and organometallic compounds – especially organotin compounds.

If a substrate’s ability to inhibit cure is unknown, a small scale test should be run to determine compatibility.

Component A of LUMISIL® 903 contains the platinum catalyst, component B the crosslinker. Even traces of the platinum catalyst may cause curing of the component containing the crosslinker. Therefore tools (spatula, stirrers, etc.) used for handling the platinum-containing component or the catalyzed compound must not come into contact with this component.

The two components should be thoroughly mixed at a 1:1 ratio by weight.

To eliminate any air introduced during mixing or trapped under components or devices a vacuum de-airing under a vacuum of 10 – 20 mm mercury for 5 – 10 min is recommended.

Curing time of addition-curing silicone rubber is highly dependent on temperature, silicone amount, size and heat sink properties of the substrate the silicone is applied on.
We recommend running preliminary tests to optimize conditions for the particular application.


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)

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