Talk Composites - The Forum for Advanced Composites

Newbie problem casting water clear sphere

http://www.talkcomposites.com/Topic21406.aspx

By SC - 6/9/2016 4:06:11 PM

Hi,

I'm a newbie to using resin, and have started a little 'shed' project in order to give me a few minutes to escape the long list of housework assignments Smile

My ultimate goal is to cast some water clear resin spheres to encapsulate various organic items (flowers, etc). I've experimented making some molds (one part and two parts) out of Addition Cure Silicone. These all appear to be fine.
http://s33.postimg.org/fyg7z6wi7/silicone_Mold.jpg

When I attempt to cast Water Clear Resin in them, the end result always  comes out partially covered in unpleasant surface ridge lines (see photo's). With my amateur eye, it appears that as the resin cures and shrinks, the partially set surface peels away from the mold at various places, leaving little contact trails.
http://s33.postimg.org/jpka50mxb/sphere2.jpg

http://s33.postimg.org/nexekkwsv/sphere1.jpg

I've experimented with different catalyst mix ratios from 0.2% to 5%, with no success yet.

What am I doing wrong? Wrong material, bad technique, environmental factors...?

Any help would be appreciated, as my lovely and patient wife will soon start asking me some awkward questions...

Thanks,
Simon
By Warren (Staff) - 6/20/2016 5:19:45 PM

How long are you leaving the part prior to demoulding?  We have seen similar effects when items are released too soon from the mould. Also what sort of size is the sphere? It may well be getting quite hot as the resin cures off and be borderline exotherming if the volume is quite large.