Confused by resin directions

[Katherine Swift]

This question comes from Kimberly:

I’m not sure if you’ll get this, or if this is the best way to ask you, but I’ve been stalled in my resin projects for some time. I got this Castin’ Craft 3” x 1 3/8” dome mold and am confused by some of the instructions on the packaging. When talking about mixing, it refers to a catalyst chart & I don’t know if it’s referring to drops of hardener per ounce of resin or what. I’m attaching some pictures – I hope you’re able to view them & would so very much appreciate any guidance you have to offer on the matter. I have some dried flowers from my Grandma’s passing in October & I know my Mom and sisters would be so happy to have a little something to have around as a memento. Thank you for all you offer in the way of resin help in general!

[Katherine Swift]

Hi Kimberly, unfortunately I can’t see the pictures, but it sounds like you are using the Castin’ craft (polyester) casting resin. Polyester resin is different in that the amount of catalyst you add is more dependent on the depth of your casting and not as much the amount of resin. According to manufacturer directions here:

https://www.eti-usa.com/sites/eti-usa.com/files/Casting-Resin-Instructions.pdf

you should add 4 drops of catalyst per ounce of resin when you cast in the mold above. It sounds like you are using this mold:

https://shop.resinobsession.com/products/half-dome-mold-mc-5?variant=965320293

which holds as much as four ounces of resin. If you are casting to fill the entire mold at once, you will need to use 16 drops of catalyst in 4 ounces of resin. Keep in mind that the heat is additive, so if you are pouring in layers, you will need to reduce the amount of catalyst by a drop or two for the resin mixed in each additional layer.

Does that help?

[Kimberly]

Yes, that definitely clears some things up. I actually didn’t realize I had gotten a polyester mold & have not worked with that type of resin yet (hence the confusion about the catalyst). Thank you for your reply & help! I will probably seek out a silicone mold for the time being.

[Kellen Ferguson]

If I am filling an 8 ounce mold all at once, how many drops of the catalyst will I need? Will the 4 drops per ounce still apply in that case?

[Katherine Swift]

Hi Kellen,

It depends on the depth of your casting. The PDF links in the previous comments should give that information.

[Charlene]

I am making a cabachon. I am using a half a silicone sphere mold. The first layer is about 3 ounces.For this I figured out. What I am unsure of is the 2nd layer. It will be a thin layer of resin coloured black(approximately 1/8 of an inch). How many drops of catalyst? I heard to use more drops in thinner layers. Also, can the first layer completely dry before adding second layer?

[Katherine Swift]

Hi Charlene,

What brand of resin are you using?

[Jeanie]

Hi, I haven’t even opened my bottles yet and I have a very simple question. I got Resin Obsession doming resin – the 1 to 1 ratio. I want to start out really small. I thought I could mix say… 2 TBSP (1 of each part). In your directions, you say that 3 ounces is the minimum for the resin to cure properly. Did I read that correctly? That’s quite a lot. (That would be a total of 6 TBSP). Is this correct?

[Katherine Swift]

Hi Jeanie,

The Resin Obsession crystal doming resin has a minimum mixing amount of 1 ounce. The Resin Obsession artwork resin has a minimum mixing amount of 3 ounces.

A quick search says 1 tablespoon equals 1/2 ounce.

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