Talk Composites - The Forum for Advanced Composites

Xencast P6 - porosity / bubbles

http://www.talkcomposites.com/Topic21571.aspx

By cliveso - 7/6/2016 7:55:20 PM

Hello all,

I have recently purchased some Xencast P60 and have cast some pieces with 5% polyurethane pigment. Unfortunately I'm getting lots of tiny bubbles stuck to the surface of the pieces and sanding makes them stand out even more. 

I'm wondering whether it's air introduced during mixing or gas generated during curing due to moisture contamination. If it's the latter case, could someone recommended a moisture scavenger or some other solution?

Attached are pictures of an unprocessed piece and a finely sanded piece (1000 grit).

Many thanks for your advice.
By Matt (Staff) - 7/7/2016 4:52:12 PM

Hi Clive,

Condensation Cure silicone does harbour moisture and although it should be perfectly possible to use condensation silicone with the Xencast P6 it could be possible that either this particular silicone is holding more moisture than usual. We've tested Xencast P6 with a range of silicones but of course we've not been able to test it with them all.

Is the silicone mould new or has it already made a few parts? - Also, do you wash the mould out (soapy water for example) before use? - If you do, this would be a prime candidate for a problem. It's strange that you had the same problem with the previous FastCast too; that resin has high levels of moisture scavenger in which made it very insusceptible to moisture reactions so I'm thinking there might be an issue with the process somehow.

One last thing, the 'sediment' in the Part A is the moisture scavengers. Are you thoroughly shaking Part A to disperse the sediment before use?

--Matt