Resin casting help needed, please

[scltrbrsl]

Hello, everybody!

I sculpt as a hobby, but trying to go professional. My figures are about 8'' (20 cm) high and 3'' (8 cm) wide, made out of either natural clay (red or white, air-dried) , or Faber Castell's children's modelling clay (wax-based, never-hardening) -- "plasticine", I believe? Not sure how it's called in English, as it's not my native language.

I've done some simple natural clay molding and casting before. I'm, however, completely new to any other kind of molding, and to resin casting. Never done it. But I'd really like to resin cast my (future) figures. I also would like to paint and varnish/coat my finished resin pieces, making them as professional-looking and durable as possible. I looked this up a bit, but I'm still unsure of the best way to do it. The main thing is that the final piece has to be of hard resin, and paintable.

Objectively:
1. Should my original figures be sculpted out of air-dried clay or plasticine? Or out of something else, and if so, what?
2. Should the mold be made out of silicone? If yes, any particular tips? If not, out of what then?
3. Any particular tip on the resin casting itself?
4. Any particular tip on the painting and finishing?

I know there are tons of tutorials online. I'm just wondering if someone has some specific tips, or some warning, like "it's never going to work out like this because of 'x' reason, you should instead do 'y'".

Thank you.

 

[Gordon Gekko]

Really, you should spend some time going over the numerous tutorials. Go to Smooth-ons website and watch the videos. Then come back and ask your questions. Until you have a better idea of the process yourself, your questions at this point are just too vague for any real answers.

 

[scltrbrsl]

Thank you for replying, and for the Smooth-on's website suggestion!

Sorry for being vague. It's just that all tutorials I find are of one or another part of the process I'm intending to do, but I can't seem to find someone who has done the whole process exactly like this -- sculpting from natural clay or plasticine, then making a silicone mold, then casting. If I come across a tutorial of, say, silicone molding, their original sculpted piece is not made from the same materials I'm intending to use. Know what I'm saying? So I'm kinda putting different tutorials together in my head, but I'm not sure it'll actually work -- I only know the parts (sculpting, molding, casting) work separately. So I'm really just trying to see if i'm maybe overlooking something, even something basic, like silicone not working with natural clay because of 'x' reason, or something like this.

So, trying to be more precise (maybe unsuccessfully), my question would be: am I overlooking something? Any special (specific, particular) tip or hint that I may not come across in a tutorial, but that you have come across in your experience? I know I can get the how-tos and the details from the tutorials, that's a bit why my question is not so detailed. I don't really have any doubt, just a feeling that maybe someone has something particular to share about it? Your website suggestion was helpful, for example.

 

[martinwilson]

Hi scltrbrsl,

Yes, often it is not possible to find a tutorial that shows exactly what you want to do with exactly the materials that you want to use. You have to learn bits and pieces from many tutorials and then experiment with combining everything for your specific project.

So I'm not going to go into much detail for each of the 4 questions you originally asked (since you can definitely find tutorials for each separate step), but I will rather try to give you some hints regarding how those questions interact as a whole...

1) Your sculpting material:
Most importantly use something that you know and that suits the scale, level of detail, and time-frame of your sculpt. If you are going to be making a silicone mould, then you can basically use anything as your sculpting material. One exception is that you shouldn't use anything that contains sulphur - such as some plasticines and latex rubbers - if you plan to use a platinum-based silicone for your mould. Also keep in mind that water and silicone don't work great together, so if you are using air-drying or natural wet clay make sure that they have dried sufficiently so as not to be wet to the touch before starting with your mould. Finally, if you want to make a bush-on silicone mould it is better to sculpt out of a harder medium so as not to damage the sculpture's surface texture during the process.

2) Silicone mould
If you want to cast resin then yes, a silicone mould is best. You basically have 2 options here: tin-based and platinum-based silicone rubbers. Tin-based is generally cheaper, is not as easily inhibited by contaminants like sulphur, and is more robust to mixing inaccuracies. Platinum-cure is less toxic and is therefore used when interacting with food or the human body, shows less shrinkage, and cured moulds can last longer. Also, tin-cure will inhibit the curing of platinum-cure, so if you think you'll ever want to make a cast out of platinum silicone then you have to use platinum for the mould too. I would suggest sticking with a simple tin-cure silicone such as Smooth-On's Mold-Max series.

3) Resin casting
Choosing the right resin comes down to knowing its appearance, viscosity and cure-time. You also need to decide whether you want to cast your pieces solid or hollow. But every kind of polyurethane, polyester or epoxy resin will work perfectly with a silicone mould. A good starting place is Smooth-On's Smooth-Cast range.

4) Painting and finishing
Different resins accept paint better than others. Do research on painting the specific resin that you chose for step 3.

I hope this helps point you in the right direction.