[Linda]

Hello!

Ive been lurking the site for a while now and just decided to join in! *w*

Im new with the resin stuff, so Id like some advice from you experts… ^^

Im trying to cast little pendants using East Coast Fiberglass resin, having little success till the moment. It seems like its fine with plastic moulds and silicone ones with a matte finish, but with the glossy silicon ones, I just cant stop it from being sticky!

Its true its been raining for a while here now, so I added a tiny bit more of hardener, hoping to solve the problem. It didnt cause cracks, but it didnt make it less sticky either. I tried putting them in a hot oven and in the freezer as well, but with little difference on the results.

Should varnishing the pieces afterwards solve the problem? They look so pretty, but are useless if I cant touch them! =[

Thanks for your attention!

[Katherine Swift]

Hi Linda,Is this the surface that is exposed to air?  If so, Im afraid thats a common problem with polyester resin.  You will either need to coat them with a sealant spray (our gloss sealer spray works well)

https://shop.resinobsession.com/collections/tools-and-supplies/products/castin-craft-gloss-resin-sealer-spray

or you can sand off the sticky surface.  It doesn’t go that deep, so you shouldn’t need to sand much.

[Linda]

 Thanks for your quick reply, Katherine!

Well, on the glossy mold its all sticky, the exposed top and bottom. I have some here Ive done its been a few days now and they seem harder (finally!) but still stick to the surface theyre on if left for too long. Ugh!

Ill take a look at that spray, many thanks! I think Ill have to sand it down anyway cause of the fingerprints (I had to put pins on them while theyre still soft), or would the spray solve it well?

Thanks!

[Katherine Swift]

Hi Linda,

Im afraid you will have to sand the fingerprints off.  At least when its happened to me, they will still be there after the layer of gloss spray.

Thats really strange that the resin isnt working with the glossy molds.  Are you sure theyre silicone?

[Linda]

 Now that you said, Im not sure anymore theyre made of silicon. I bought them under that description, theyre food molds. As I said, the one with a matte finish works wonderfully, but the other one is just a nightmare – maybe its just rubber then. =[

Think Ill try to make a little profit with the one I can use and buy hard plastic ones. I really cant afford to waste any more material – and sanity! lol

Its a shame you cant ship that spray outside the US. Ill have to pop to one of our craft shops and see if I have any luck.

[Katherine Swift]

Good luck with the spray!

As for the molds, silicone is generally inert, so Im wondering whats with the mold thats keeping the resin from curing.  If the mold was made from a sulfur model, leftover sulfur can keep things from curing.   Outside of that, I dont have any good thoughts.  Food grade silicone should be fine….

What is the thickness of the castings?  Polyester resin is such a strange beast.  Perhaps you need to add even more hardener to get it hotter to cure a thick casting.  (The manufacturer should be able to help you with this.

[Linda]

 Mmmm… The castings are pretty thin, they have around 8mm or so, it shouldnt be a problem. Theyre not large either, and I use only dry materials such as glitter or sprinkles, didnt even try with flowers yet. 

Maybe itd be a good idea to heat up the mold before pouring the resin? Or heat up the resin a bit before pouring? Or before demolding… (till the day she sets the house on fire!).

The plastic molds feel very hot while theyre curing, tho. So does the resin, I worked with a bit of it when it was jellyish.

Im using a 2% ratio for the mix, Ill try with a few drops more, maybe a dehumidifier. Such bad timing, it just started raining when my materials arrived! =[

[Katherine Swift]

I dont know that heating up the mold will help.  Its not going to hurt, but I dont know how much that will help since youre telling me your resin is getting warm.

8 mm is actually thin for a polyester casting.  Im thinking you need more catalyst for the amount of resin youre using.  Ask the manufacturer what they recommend.

Polyester resin is supposed to be moisture tolerant, so I dont know as though running a dehumidifier will help, but it wont hurt.  Sounds like youre using dry inclusions, so that shouldnt be a problem either.

If you get a good fix, let us know what you did!

[Katherine Swift]

This article will help: https://www.resinobsession.com/resin-frequently-asked-questions/why-is-my-resin-sticky/

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