Squiggly Lines in Resin Molds

[CrystalClear]

Hello,
I am having troubles with some resin casting. I am using Clear-Lite Polyester Resin from TAP Plastics. I am pouring molds of crystals that are about 3-5" H and 1.5" diameter. I have about a dozen silicone molds of the crystals that I use to cast the resin. A few of resin cast almost always come out of the silicone mold with little squiggly lines on them. They look like water has run down the mold and hardened in that position. It makes a webbing effect, as the squiggly lines hardened in all directions not just up or down.
I cannot figure out what causes it. It seems that some of the silicone molds this happens almost always and some of the silicone molds it never happens to, even though I pour all the molds at the same time from the same batch of resin that I mix. I mix a 16 oz of resin at a time with correct amount of catalysts and distribute it between 8-9 different molds. I am pouring the molds all at once, not in layers. I am measuring out the catalysts and pouring them in a temperature controlled environment.
Any answers will be a great help! Thanks!

Another resin curing topic...
Can I leave the resin molds to cure in a cold garage? Is there any kind of equipment (DIY equipment, not really expensive machinery) that can contain the smell of the resin so I can leave them to cure in my temperature controlled basement and not have the fumes engulf the entire house? I was wondering if an old refrigerator would keep the smell contained?

Thanks!!

[johncast]

Hi Crystalclear

Seen and had this problem many years ago when I was starting with resin casting and trying out all sorts of resins and rubbers. I think I could sum up your problem with one word, Polyester.

Polyester resin is ,in my mind for some other work ,not model castings or jewellery castings etc.

Your moulds are fine , but the polyester reacts to the rubbers and causes a pattern called Tryping, where the resin casting has all the lines over the surface once set. Looks like the surface of wet glue of a joint that has been pulled apart.

You need to get on to a clear urethane resin and try that out, if this cures the bad surface than I think the other problem with the smell of the resin will be solved as well. Give your moulds a good clean in warm soapy water before you use the new clear Urethane resin. Good luck

Johncast

[CrystalClear]

Hi Johncast,

Thanks so much for the information. I will try it out!

[Fleafa]

Polyester resin is of the devil. Leave it to the boat-makers.
PU costs more but is much easier to work with.