Molding and casting by Kayakasaurus

[Kayakasaurus]

Another step closer! I redid those vents that were wrong and added one where Reinier said. Here is what I came up with for the tail club. I'm almost done tricky but fun. If I can't find acrylic lacquer maybe I'll pick some up from the store. Vaseline first though!

I am wondering why the vaseline, is it to smooth your clay? Looks fine to me, just smooth any rough bits with a tool, clean the clay from the model with some solvent and seal it with acrylic, then apply mould release.  You can use the solvent that you clean your model with to further smooth your clay before the acrylic if you wish.

I don't remember where I heard Vaseline but I was going to use it to clean and smooth. Maybe I meant acetone... To many chemicals! What solvent do you recommend? Then I can get started! You think the club turned out ok? Thanks


EDIT: I went ahead and used rubbing alcohol and made it all smooth. Now I'll go search for acrylic.

[Doug Watson]

I don't remember where I heard Vaseline but I was going to use it to clean and smooth. Maybe I meant acetone... To many chemicals! What solvent do you recommend? Then I can get started! You think the club turned out ok? Thanks
EDIT: I went ahead and used rubbing alcohol and made it all smooth. Now I'll go search for acrylic.

The club looks great!

[Kayakasaurus]

Hello! I finally poured the first half of the silicone mold! ! I used clear coat spray paint to seal the plasteline and "Fix-it-all" water putty to make a mold jacket. Everything worked but there are a TON of bubbles in the silicone, that dragon skin is so goopy.   Fortunately there doesn't seem to be any bubbles that ruined the inside surface... We'll see. Tomorrow I can rebuild the channels and finish this thing! However I did make the mistake of removing the silicone from  the positive Shuno to remove the clay. Now I have to fit it back in. It did make cleaning easier though.

I found an alternative to buying this expensive silicone online. Mixing 1:1 ratio of silicone caulk with corn starch. The corn starch sucks in moisture curing the silicone. Just Google; "home silicone tube cornstarch". There are some videos on YouTube where you can see the finished project. If it's one of those crafty tween videos though I recommend skipping to the end of the video and save yourself the agony of listening.  Seems promising... What do you think?

[Kayakasaurus]

I got it back in no big deal. I've been trying to think of a small buisness name... "Midnight Molders" seems appropriate lol  .

[reinier zwanink]

Your comming closer
Getting your very first cast in hand is a real kick

[Doug Watson]

I got it back in no big deal. I've been trying to think of a small buisness name... "Midnight Molders" seems appropriate lol  .

Looks good.
I have never mixed cornstarch with silicone caulk, I'll leave that one to you. We did use clear silicone caulk to mould an ocean rock face in Nova Scotia once for the museum. We thinned the silicone with Varsol to improve the viscosity and we backed it with chicken wire so we could form the mould when we got back to the shop. We built up the layers over several days.

[Kayakasaurus]

Well I wasn't being to smart when I first applied the clay. For the most part I split it down the center of the tail but then I covered up where the tail goes down. That place Reinier said air might get trapped is actually more dramatic. So the vent I made goes to the side of the tail not the base. I'm not sure what to do... What do you think?

[Doug Watson]

Well I wasn't being to smart when I first applied the clay. For the most part I split it down the center of the tail but then I covered up where the tail goes down. That place Reinier said air might get trapped is actually more dramatic. So the vent I made goes to the side of the tail not the base. I'm not sure what to do... What do you think?

What you can do is bring the vent up to the figure and when you get to the figure flare the end like a V shaped flag to reach the spot near the anus. It will mean a bit more repair on your cast but it could prevent an air bubble.

[reinier zwanink]

I would do that to
One more thing
Does that piece of silicon between the rear legs look like a problem or is it just me

[Doug Watson]

I would do that to
One more thing
Does that piece of silicon between the rear legs look like a problem or is it just me

I should have mentioned if you want to limit the extra material you will have to remove if you cut a flag shaped piece of thin plastic to fit snug against the belly you can place it at the end of your vent and then run your vent up the outer edge of the plastic to the high point on the belly. The plastic will form a thin dam that will prevent a lock and limit the extra material to remove. You can seal the plastic to the belly with some clay. With either method you will have to be careful since your rubber is thick, not to move it when you pour the second half.

Yes reinier that piece of rubber looked like an air bubble to me but I think it just sticks out. He might want to slice it off with a sharp blade otherwise he will have to be sure to get the new rubber behind it without causing a bubble.

[reinier zwanink]

I would surely cut that down for it would improve seal of a closed mould

[Doug Watson]

I would surely cut that down for it would improve seal of a closed mould

As long as the mould is thick enough there, he wouldn't want to cut through to the other side.

[Kayakasaurus]

I solved the problem with the base of the tail. I just made a little clay wall and used gravity to pour a little silicone up the wall reaching the air trap point so now I can connect a regular channel to it. That silicone that curves in between the legs is just the way the clay was shaped where I couldn't see much. It's plenty thick there and I plan on trimming it, along with a couple other places. Thanks!

[Doug Watson]

I solved the problem with the base of the tail. I just made a little clay wall and used gravity to pour a little silicone up the wall reaching the air trap point so now I can connect a regular channel to it. That silicone that curves in between the legs is just the way the clay was shaped where I couldn't see much. It's plenty thick there and I plan on trimming it, along with a couple other places. Thanks!

Are you sure that the silicone has bonded since the first half will have trace mould release on it?

[Kayakasaurus]

Yes it worked great. I have all the channels filled and poured the first layer of silicone on the second half... Unfortunately the mold release decided NOT to work and I had sprayed a lot on. Although it worked just enough for me to be able to tear the new silicone off but it ruined it. Thankfully the first half and most of the clay channels are all intact so I can still finish it. I think I will be using Pam cooking spray instead of the mold release, in my tests it worked better. So, a minor setback, but I will be back at it tomorrow! 

[reinier zwanink]

Yes keep that nice and wet
Often you this it will do but still it sticks so dont go cheap
You can clean it afterwards

[Doug Watson]

It is surprising that the release didn't work since I thought it was one of the ones smooth-on recommended. However it wasn't their first choice. Their first choice was Ease Release® 200, if you plan on doing this commercially I would get the recommended release. I have never used Pam but one word of caution using any release, if you put it on thick you can lose detail in your cast, plus you want a release that is either paintable or easily removed.

[Kayakasaurus]

[reinier zwanink]

Nice
The club still has a problem thou
How is the rest?

[Kayakasaurus]

Well I'm finally casting! Thank you to Doug and Reinier for your help! The first two each had unique problems of their own... That's why you see them from the top. But I have the amount of resin down and my third cast came out 95% perfect, even the club turned out. It's only problem is an air bubble in the front right foot. Here he is! BTW I sprayed some grey primer on to see the details.