Materials Advice Casting Polyurethane eyes

there are several resin products out there, A/B, UV being the main difference, and then we get down to how soft/hard/clear the resin cures. heat is for getting rid of the bubbles so it rises up, some guy on youtube did an experiment and say as far as cheap alternatives to a vacuum goes, a heatplate works really well. as far as i can tell, you dont need mould release with silicon moulds, also mould does break after using it an x number of times, so dont be surprised when it does.

i say go for the uv resin (pro: faster to cure, con: more expensive), that way you can do a bunch at once, instead of waiting around for the a/b stuff to cure for each pair. Ive never tried the resin you mentioned so cant comment.

 

Another thing to consider is humidity. From my own experience I've learned that making sure the humidity is low does a lot more for avoiding curing mishaps than heat does. Heat mostly just heats the whole thing up and with the fast curing resin you linked you won't have time for that. It can also cause bubbles to simply expand, rather than rise, especcially in matte surfance molds and if I read the "finger print texture" right, that is what you've got there. Heat will also speed up the cure slightly.
You probably don't need a mold release agent, but if you do, you need to choose it based on what resin you use. You also need to know what material the mold is made from, as some types of silicone don't like some release agents. I you find you need it, contact the maker and ask for recommendations.

The cure times differ quite a bit and that may or may not matter to you. If you intend to make large batches from a single mold, a short cure time is great as you can make one cast after another without spending much down-time. A fast cure gives less time for bubbles to form, but also less time for bubbles to rise, so witchever is better for you will depend on temperature, humidity and equipment available in you work room.
Oh, and do you research so that you use the proper protective gear and an appropriate work area! You don't want to accidently risk the health of other people or pets in your house.

As for the varnish, I can't see any reason why it wouldn't work, but you won't know for sure until youv'e tested it with the resin and any pigments or paints you intend to use. It won't work the same as resing would as it is intended to be used in thin layers, but if you are ok with that it's probably usable.

 

Have you tried using UV to make white bases? I'm unsure if that's what you're suggesting, but I've tried tinting UV and curing it and it doesn't work since it cures via UV light which cannot penetrate all the pigment. If you're going for very opaque white bases then I suggest a 2 part resin, I use crystal epoxy resin 2 part and tint it with white pigment. It takes about a day to cure. You don't need release agent or anything like that but heat does help get the bubbles out.

You can then use UV resin for the doming and coating. There are a lot of tutorials out there I recommend sfishfish on YouTube.

 

more like how people who make resin layer painting or resin jewellery does it, a thin layer to coat the eye mold, paint, more resin, pop it out and flip the eye around, putty paint the irises, dome the eye

 

ahh ok that makes more sense! I still had trouble curing a thin layer of tinted UV but in fairness this was ON a surface so the light couldn't reach the back, I imagine it would cure if you get both ends exposed to light.