Can you use drywall spackling to fill in tiny holes on Ultracal 30 mold? And other molding and casting questions.

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Egon Spengler

Master Member
Can you use drywall spackling to fill in tiny holes on Ultracal 30 mold?

I have a bad feeling I already know the answer. Probably no right?

The bad feeling comes from the fact I already used some and it's currently drying. If it's not good I hope it's easy for me to get out.

I made a two part mold for a mask sculpt. Unfortunately some of the ultracal from one half stuck to the other half, so I have tiny holes in the front face which is well intact but some noticable cracks on the back of the head. I was going to patch them with more ultracal but it's so hard to sand down excess if it cures.
 
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udog

Active Member
It shouldn´t be a problem. It will be softer than UC30 so probably it will come out with the first pull you cast and you might have to fill in again for more castings. But nothing wrong with it in first instance.
Also it shrinks, sometimes you´ll have to fill in twice.
You can also fill the cracks with clay, thinking of non-permanent fixing.
 

Egon Spengler

Master Member
It shouldn´t be a problem. It will be softer than UC30 so probably it will come out with the first pull you cast and you might have to fill in again for more castings. But nothing wrong with it in first instance.
Also it shrinks, sometimes you´ll have to fill in twice.
You can also fill the cracks with clay, thinking of non-permanent fixing.
Thanks! If I use clay or spackling will I need to seal it in the mold so silicone won't stick to it and wet it up all weird?
 

udog

Active Member
Spackling is some kind of softer plaster so no need to seal it as I see it. Water based clay wont affect silicone, no sealing either. You can also use oil or wax based clay, non sulphur ones (Chavant NSP, Monster Makers...) and smooth it out with IPA alcohol.
But if you want to try to avoid silicone sticking to all these and pulling it out yo could try sealing someway. Not sure if it will work.
The only thing is that your texture wont be the same in the repaired areas as in the sculpt.
 

Egon Spengler

Master Member
Spackling is some kind of softer plaster so no need to seal it as I see it. Water based clay wont affect silicone, no sealing either. You can also use oil or wax based clay, non sulphur ones (Chavant NSP, Monster Makers...) and smooth it out with IPA alcohol.
But if you want to try to avoid silicone sticking to all these and pulling it out yo could try sealing someway. Not sure if it will work.
The only thing is that your texture wont be the same in the repaired areas as in the sculpt.
Thank you so much for the great info! :) You've really helped!
 

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Egon Spengler

Master Member
Another question I have is that I want the mask I am making with this mold to fit closely to my face. I am going to make a mold of my headcast of my head and recast it in a light weight plastic. I want to use that as a positive in the mold. I was thinking of just filling the front of the mold with Silicone and lowering the headcast into it carefully, matching up where the mouth and eyes need to go. Then letting the front silicone cure. Then I was thinking of closing the front and back of the molds together, leaving the positive in place and then carefully filling the void in the back of the mask with silicone. Another issue is this is for an alien grey mask so the top of the head is pretty bulbus. Filling that entire area with silicone may make the mask rather heavy.

Im throwing a million ideas around in my head trying to figure out how to get this right. Ive also thought of putting the two halfs of the mold together, strapping them shut and then completely filling the sean inside with clay, to have no seam in tje end cast. I'd smooth and sculpt the clay to better match up with the mask then do a layer of slush cast into the mold. Do you guys think that would work? I dunno. Going in circles here lol
 

udog

Active Member
If I understood well, you already sculpted and molded and now you want it to fit closely on your head?
What is usually done is using a head form (could be your lifecast) that ideally has also the shoulders there and reference keys. And you sculpt on top of that. Then you mold your sculpt and the lifecast/manequin (that has it´s refference keys) becomes part of the mold, this is, the core.
After you open the mold and take/clean the clay out you will have a three part mold (if you molded the sculpt in two parts). Front part negative+back part negative+core (head).
Once closed the standard would be injecting the silicone filling the cavity between the core and the negative parts of the mold. This would be done (injecting, if the core is hollow) through the interior of the core´s head where previously one would have created an injection hole.
If one is working with a full core with no shoulders it can also poured through the neck area once everything is closed. I can also be poured through a pouring hole as described when injecting.
This is the way that everything fits in place (eyes and mouth) and snugs tight to your face.
Now, if I understood well you skipped this part. Anything you do now will be quite random. You can try what you say but:
If you fill the front and place your lifecast in most probably you will get a huge overflow of silicone out of the mold.
Placing the lifecast won´t be easy, you want at least 4mm silicone thickness in a mask. You might have to work out some kind of rigging for the lifecast and the mold so it holds in place exactly where you want. And then fill.
Another option, taking in account at what stage you are now, is using thickeners. It could make things easier. Brushing a thick layer and then placing the lifecast in. But the downside is that thickeners compromise seriously silicone properties. You will loose stretchiness and tear strength .
Also, in any of these cases, make the back part when the silicone is not totally cured as silicone won´t bond to itself that easy once cured.
Slushing silicone doesn´t sound good to me. Remember you need a minimum thickness and that silicone is not latex, it takes a time to cure and it´s not intended for rotococasting. Not saying it can´t be done, but not sure what will come out.
The standard way for silicone maskmaking is more or less what I tried to describe in the first part of this answer.
As for heavy parts, yes, silicone is heavy and it could cause sagging or similar issues. Some mask makers use Soma Foama (silicone foam) to fill heavy parts. Not easy to do.
 

Egon Spengler

Master Member
If I understood well, you already sculpted and molded and now you want it to fit closely on your head?
What is usually done is using a head form (could be your lifecast) that ideally has also the shoulders there and reference keys. And you sculpt on top of that. Then you mold your sculpt and the lifecast/manequin (that has it´s refference keys) becomes part of the mold, this is, the core.
After you open the mold and take/clean the clay out you will have a three part mold (if you molded the sculpt in two parts). Front part negative+back part negative+core (head).
Once closed the standard would be injecting the silicone filling the cavity between the core and the negative parts of the mold. This would be done (injecting, if the core is hollow) through the interior of the core´s head where previously one would have created an injection hole.
If one is working with a full core with no shoulders it can also poured through the neck area once everything is closed. I can also be poured through a pouring hole as described when injecting.
This is the way that everything fits in place (eyes and mouth) and snugs tight to your face.
Now, if I understood well you skipped this part. Anything you do now will be quite random. You can try what you say but:
If you fill the front and place your lifecast in most probably you will get a huge overflow of silicone out of the mold.
Placing the lifecast won´t be easy, you want at least 4mm silicone thickness in a mask. You might have to work out some kind of rigging for the lifecast and the mold so it holds in place exactly where you want. And then fill.
Another option, taking in account at what stage you are now, is using thickeners. It could make things easier. Brushing a thick layer and then placing the lifecast in. But the downside is that thickeners compromise seriously silicone properties. You will loose stretchiness and tear strength .
Also, in any of these cases, make the back part when the silicone is not totally cured as silicone won´t bond to itself that easy once cured.
Slushing silicone doesn´t sound good to me. Remember you need a minimum thickness and that silicone is not latex, it takes a time to cure and it´s not intended for rotococasting. Not saying it can´t be done, but not sure what will come out.
The standard way for silicone maskmaking is more or less what I tried to describe in the first part of this answer.
As for heavy parts, yes, silicone is heavy and it could cause sagging or similar issues. Some mask makers use Soma Foama (silicone foam) to fill heavy parts. Not easy to do.
I really appreciate your help. You're super knowledgeable with this stuff. I wish I had thought of the life cast with reference keys. Theres so much info in your post it's taking me a minute to think of what I might go with. I might try making a lightweight copy of my life cast head and still do the thing where I lower the head down into the front. Maybe with some very thin bamboo skewers in it that will go over the edge of the mold where I want it to level. Might even dremel little slots for them to sit in in the mold. Will have to clean up the little holes it'll make in the mask but I think it'll be worth it. Then close the second half down on it, with the head kind of floating in the mold with the help of the sticks. Then just pour silicone down in through the neck/shoulder area. I'm sure my first attempt is going to be a mess, but I'll try until I get it right. I might just try to fill out top part of his head with some foam or cotton padding instead of using the soma. I've got time to work it out :) When I'm done I want to post a topic with all the pics and progress. Thank you so much for your help!
 

udog

Active Member
I really appreciate your help. You're super knowledgeable with this stuff. I wish I had thought of the life cast with reference keys. Theres so much info in your post it's taking me a minute to think of what I might go with. I might try making a lightweight copy of my life cast head and still do the thing where I lower the head down into the front. Maybe with some very thin bamboo skewers in it that will go over the edge of the mold where I want it to level. Might even dremel little slots for them to sit in in the mold. Will have to clean up the little holes it'll make in the mask but I think it'll be worth it. Then close the second half down on it, with the head kind of floating in the mold with the help of the sticks. Then just pour silicone down in through the neck/shoulder area. I'm sure my first attempt is going to be a mess, but I'll try until I get it right. I might just try to fill out top part of his head with some foam or cotton padding instead of using the soma. I've got time to work it out :) When I'm done I want to post a topic with all the pics and progress. Thank you so much for your help!
All right!. You got the idea, now it´s a matter of trial error.
I like the idea of the lightweight head, easier to manage. Also the idea of making some kind of reffernece/slots or whatever. Probably if you sit and brainstrom a little you might be able to pour with the mold tightly closed (and core inside) with what you have. I would try to avoid doing it in two stages if possible. I´m sure you can find a way. The ideal is to get a one pour cast.
Bear in mind that if you use the lightweight head, silicone will tend to make it "float up" when poured. That´s why I would try to figure out the way of attaching your light weight head to the mold someway and fill it closed. Maybe using the neck flange area of the mold. I see it possible, don´t know if I´m expressing myself clearly.

Pu flexible foam could be an idea to avoid weight. You can also think about using mesh, or even fiberglasss (making sure it wont come out) to stiffen the heavy parts. It would help to avoid sagging if there´s to much weight.

What silicone are you planning to use.
Mask standard is Ecoflex 00-30.
 

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Egon Spengler

Master Member
All right!. You got the idea, now it´s a matter of trial error.
I like the idea of the lightweight head, easier to manage. Also the idea of making some kind of reffernece/slots or whatever. Probably if you sit and brainstrom a little you might be able to pour with the mold tightly closed (and core inside) with what you have. I would try to avoid doing it in two stages if possible. I´m sure you can find a way. The ideal is to get a one pour cast.
Bear in mind that if you use the lightweight head, silicone will tend to make it "float up" when poured. That´s why I would try to figure out the way of attaching your light weight head to the mold someway and fill it closed. Maybe using the neck flange area of the mold. I see it possible, don´t know if I´m expressing myself clearly.

Pu flexible foam could be an idea to avoid weight. You can also think about using mesh, or even fiberglasss (making sure it wont come out) to stiffen the heavy parts. It would help to avoid sagging if there´s to much weight.

What silicone are you planning to use.
Mask standard is Ecoflex 00-30.
Ecoflex 0030 or 0035 :)
 

udog

Active Member
Ecoflex 0030 or 0035 :)
Great, but forget what I said about using thickeners with that silicone, they wont work with ecoflex I think. Too low viscosity for thickening.
It´s ver runny (that´s good for your purpose), so if you end up with an idea that allows you to pour with the mold closed make sure it´s tigthly closed and seal the outside part of the seam with clay or similar.
 

Egon Spengler

Master Member
Great, but forget what I said about using thickeners with that silicone, they wont work with ecoflex I think. Too low viscosity for thickening.
It´s ver runny (that´s good for your purpose), so if you end up with an idea that allows you to pour with the mold closed make sure it´s tigthly closed and seal the outside part of the seam with clay or similar.
Awesome! Thats great to hear! Thanks again! :)
 
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Egon Spengler

Master Member
I'm just so annoyed at how wonky the seam is when it comes to my mold. There are gaps where there shouldn't be. I really wanted it to be a smooth transition.


Edit: I bought some Apoxy Putty on Amazon. I'm going to put some wax on one half of the mold and try to resculpt the mold along the seamline using it so theres a nice smooth transition.

If there is still excess silicone after the fact is there a product I can use to dissolve it and blend it?
 
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udog

Active Member
I'm just so annoyed at how wonky the seam is when it comes to my mold. There are gaps where there shouldn't be. I really wanted it to be a smooth transition.


Edit: I bought some Apoxy Putty on Amazon. I'm going to put some wax on one half of the mold and try to resculpt the mold along the seamline using it so theres a nice smooth transition.

If there is still excess silicone after the fact is there a product I can use to dissolve it and blend it?
Apoxy putty is harder than your mold, be careful if you need to sand that down. The rest of the area will be softer and might go down faster.
You can try doing the same thing, but with plaster. Soak the area in water and then add plaster so it bonds.
About a product that dissolves silicone to blend it, sorry, no magic there as far as I know. You will have to cut down and flashing job with thickened silicone if necessary.
When you have that casting out post here, and sure some tips will come out.
 

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