Surface preparation:
All surfaces must be clean and free of contaminants that will inhibit the cure of ELASTOSIL® SOLAR 3211. 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.
Mixing:
ELASTOSIL® SOLAR 3211 is processed with ELASTOSIL® CAT PT, ELASTOSIL® CAT PT-F or ELASTOSIL® CAT UV as curing agent. The two components need to be thoroughly mixed at a 9:1 or 10:1 ratio by weight or volume. Mixing can happen either manually or by automatic metering lines equipped with static or dynamic mixing devices.
Caution! ELASTOSIL® SOLAR 3211 contains the crosslinker, while the curing agents of the ELASTOSIL® CAT series contain the platinum catalyst. Since even traces of platinum catalyst may cause gelling of ELASTOSIL® SOLAR 3211, all tools (e.g. spatula, stirrers, mixing cups etc.) used for handling either the curing agents or the catalyzed mix must not come into contact with ELASTOSIL® SOLAR 3211 by mistake.
Material application:
To eliminate any air introduced during mixing and dispensing or trapped under components and devices, a vacuum encapsulation is recommended. Alternatively, ELASTOSIL® SOLAR 3211 and the respective curing agent can be deaerated individually prior to use in order to remove absorbed air; applying a vacuum of 25-50 mbar for 10-15 min is recommended.
Curing:
Though curing by heat is possible, ELASTOSIL® SOLAR 3211 typically is processed at room temperature. Preferred curing agents are ELASTOSIL® CAT PT and ELASTOSIL® CAT PT-F. Besides, ELASTOSIL® CAT UV allows a UV-activated curing of ELASTOSIL® SOLAR 3211.
Please note: the curing time is highly dependent on the type of curing agent used, processing temperature and both the size and the heat sink properties of the components being potted, encapsulated or coated. For catalyzed mixtures containing ELASTOSIL® CAT UV as curing agent, the curing speed additonally depends on irradiance and irradiation time. General information about the respective pot life and curing time is given in the table "Catalyzed".
At room temperature the level of Sh hardness typically reaches 75 % of the final value within 1 to 3 hours or even witin minutes, depending on the type of curing agent used. It is therefore possible to demould casted articles much earlier than indicated by the curing time values given in the table "Catalyzed".
Besides, the curing speed of ELASTOSIL® SOLAR 3211 can be adjusted within wide limits by WACKER® Catalyst EP or WACKER® Inhibitor PT 88 to suit the processing requirements of the particular application. Adding WACKER® Catalyst EP to the respective curing agent increases reactivity, i. e. pot life and curing time are reduced. WACKER® Inhibitor PT 88 is a pot life extender and thus prolongs pot life or curing time, when added to ELASTOSIL® SOLAR 3211.
Pigmentation:
ELASTOSIL® SOLAR 3211 is colourless, transparent and crystal clear. If necessary, the product can be pigmented by adding up to 2 wt. % of ELASTOSIL® COLOR PASTE FL.
Detailed information about processing, modifying curing speed and pigmentation is given in our brochure “ROOM TEMPERATURE VULCANIZING (RTV) SILICONES - MATERIAL AND PROCESSING GUIDELINES”. We recommend running preliminary tests to optimize conditions for the particular application.
Removal:
If removal of the silicone from machines or dispensing equipment is necessary, white spirit or similar nonpolar solvents are recommended. However, cleaning ideally should take place before the silicone is fully vulcanized. Cured silicone can be rubbed off and removed mechanically, if necessary in combination with a swelling agent (solvent).
