Handy Hints
Painting Translucent Silicone RTV 4408 & 3320
We receive many calls from customers wanting to paint on to silicone or polyurethane rubbers. To obtain the best adhesion for paint to adhere to silicone:
- Use a one part low modulus silicone sealant Rhodorsil 10 translucent, from our sealants range.
- Add either white spirit or Di-Limonene solvent to dilute and lower the viscosity of the one part silicone (The amount of solvent use depends on the application).
Painting Evergreen 10 Polyurethane
Evergreen 10 is now being used more and more in place of translucent silicones. It is very competitively priced with a low shore hardness, high tear strength and a great translucency to its appearance. There are two possible methods for this job:
Method One – Use Precote 21 Clear, inmould primer & Mac-Wax release agent (must be a wax based release agent).
- Spray wax release agent inside mould covering all areas and allow to dry.
- Apply a thorough coverage swill coating of Precote 21 (this s a low viscosity liquid, so drain back into the pot). Allow to dry for half an hour.
- Mix rubber and pour into mould cavity.
When rubber is demoulded 16 hours later, the Precote should leave the rubber surface etched and ready for acrylic inks and other paints to be applied. Once painted, a second Precote coating can be applied over the top if required.
Method Two – Take some mixed Evergreen 10 and add oil based So-Strong pigments to achieve different colours. Then stipple onto the surface of the rubber. This method was used by Jim Henson's creature shop when a creature being made had high percentages of flexbilzers to soften certain parts, and it was leeching oil. Remember when using Evergreen 10 as a paint base, only mix small amounts that can be used within the pot life time.
This hint appeared in our Spring 2003 Broadcast Newsletter.
