Talk Composites - The Forum for Advanced Composites

Opacity of epoxy Resin

http://www.talkcomposites.com/Topic27377.aspx

By tonib - 6/26/2018 9:52:03 AM

Hi,
Problem Definition: My company needs to make a (initially) small number of enclosures to house a PCB, some LED lights and a motion sensor. Plastic injection costs were a joke, so I decided we would try o roll our own.

I purchased the  Xencast Resin Casting Starter Kit on Warren's recommendation, and we created a small box to test whether we felt this could work. It jolly well did and we were gobsmacked at how good the results were. Thank you Warren!

So we are now at the next stage. We've purchased more silicone rubber and more resin. This week end we will 3D print the revised design and create a mould. So far so good. Here comes the question:
The LED lights are mounted on the board, and we need to make a part of the front panel THINNER so that the lights will show through.

The resin I bought is white opaque. I know that resin can be absolutely transparent, but is there something in between? If there isn't a 'ready mixed' semi-transparent epoxy, do you know if there are opaque pigments that can be added to control the opacity of the result?I have also bought some transparent pigments, and I am holding on to them for further experiments.
Thank you in advance.
By tonib - 6/26/2018 12:38:34 PM

 
Warren (Staff) - 6/26/2018 12:10:35 PM
Glad the initial castings worked out well.

Generally speaking clear casting resins are specifically clear for their intended use.  Formulating a clear resin can have its manufacturing difficulties and costs associated with it. 

I am not aware of any  "Fast Cast" type PU casting resin that is clear or semi-translucent..  The Xencast P6 Toughened Polyurethane Casting Resin  is a bit more translucent than the standard P2 Fast Cast so in a section only a couple of mm thick, I would expect some of the LED light to show through as a glow.

P6  is  a bit more fiddly to use - ideally it needs degassing for best results and it is more moisture sensitive  than the P2 Fast Cast.  For that reason we would recommend Addition Cure silicones as condensation cure silicone moulds can have moisture within them.

Alternatively you can use a completely clear resin, and then add either opaque or tinting pigments to them to get the shade and desired level of light translucency you want..

Thanks Warren. I've started looking at the pigments on offer. I'll experiment within the next couple of weeks and report on the result.
T