100% Silicone Caulk Molds — Round 2, Fight!

Mold ALL the things!
Mold ALL the things!

I’m working on the Plaster of Paris casting post, I swear!

I just keep getting sidetracked with all the fun things you can do with caulk… and on that note, here’s a follow-up to the first post on this topic.

I’m now halfway through my third tube of caulk and using the bucket of soapy water to cure the Silicone is still my go-to method. Someday I’ll try the cornstarch method again, but I’ve learned a few other fun things while experimenting.

As always, click to embiggen! ๐Ÿ˜€

Topics Below: Coloring Silicone Caulk, Casting Silicone Caulk in Plaster Molds, Making Plaster Mother Molds, Push and Press Mold Making, Hot Glue Molds

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Coloring Silicone Caulk

Hot Glue Surgery
Hot Glue Surgery

I’ve complained before about the fact that it can be hard to tell there the silicone caulk mold is because it’s a transparent color. So I decided to try taking part of the cornstarch tutorial –the acrylic paint bit– and see if I couldn’t make it work with the soapy water method.

Trying to dye the water itself blue seemed a bit much, so I just worked the silicone around like normal until it was the consistency of clay. Then instead of molding immediately, I added a drop of blue paint and worked it around above the water until the paint was well mixed.

Most of the paint ended up all over my hands (note to self: gloves!) but the silicone came out nicely colored!

Casting Silicone Caulk in Plaster Molds

Casting Colored Silicone Caulk in Plaster Molds
Casting Colored Silicone Caulk in Plaster Molds

Now that I had blue silicone– what to do with it?

Why try using it to cast something, of course! (I’ve never claimed my wild tangents art make sense…)

Oddly this is not something I’ve seen anyone else try. Probably because they didn’t have any Plaster of Paris molds lying around. The powdery nature of the plaster makes them perfect for casting slightly-sticky things, but a Sculpey mold might work well too.

Colored Silicone Caulk Casts from Plaster Molds
Colored Silicone Caulk Casts from Plaster Molds

The three castings actually came out rather well, although if I do it again I’ll make sure only to use enough to just fill the mold, the extra was hard to trim off evently.

Alas, the silicone caulk picked up every defect in the mold (boo!) but did an excellent job otherwise. Since I’m not an expert at making defect-free molds, this will take a bit of practice to perfect.

Of course I have no idea what to do with them once I made them– so they really are more of a novelty item right now.

Who knows, maybe I’ll deduce a way to make magnets out of them! ๐Ÿ˜‰

Making Plaster Mother Molds

Press Mold Sculpey
Press Mold Sculpey

The grand plan waaaaaaay back when I started this whole adventure was to make cheap silicone molds that I could use my super sculpey with. I was going to take that basic sculpey shape and then customize it into various horses, saving the step of having to recreate the base each time.

But after I cast the first horse head I realized that pushing sculpey into the molds, even the soft super sculpey was enough to deform the molds. As you can see from the picture the first attempt (bottom) turned out a lot more draft than generic lightbred.

Silicone Caulk Mother Molds
Silicone Caulk Mother Molds

The top right attempt was made by building up a super sculpey mother mold (as a test). It work okay, but clearly I needed a sturdier alternative.

Which was where the Plaster of Paris came in…

I only bothered to make interlocking bits (ie. holes/indentations) on one of the silicone molds. It turns out the bumpy nature of the hand-shaped molds was enough to make them fit snugly.

All I did was wey the molds and put them into a plastic dish upside-down and then pour in plaster around it. The plastic casting dish/square/thing is flexible enough that I could pop the whole thing free when I was done.

Silicone Caulk Plaster Mother Molds Assembled
Silicone Caulk Plaster Mother Molds Assembled

That left me with silicone molds that popped into (and out of) the plaster mother molds easily– but gained enough firmness from the plaster to allow me to push mold easily.

…Which turned out to me mostly-sort-of-useless when I swapped to casting with plaster instead.

Push and Press Molding

One more note on the building of silicone molds!

Silicone mold making using a Mother Mold
Silicone mold making using a Mother Mold

There are two basic ways to mold something using the caulk: either you put a blob of caulk on the table and push the piece into it, or you put the piece on the table and push the caulk down onto it.

With the first you end up with a flat bottom to the mold, which makes it MUCH easier to use, but have problems with the mold expanding as you push down on it. I’m lucky that most of my pieces are small and I can carefully reform them as I push (see the very top photo on the post), but the larger pieces I had to get creative with.

I used the square plastic square mold, that you can see in the picture, to help contain it, but it was just too big. So then I created a much smaller ring mold by casting plaster around the bottom of a plastic cup. It turned out just about perfect for one horse head and one mane! ๐Ÿ™‚

Silicon and Sopy Water Mold
Silicon and Sopy Water Mold

You have to be careful to make sure the piece is level, but you don’t have to worry about gaps between the caulk and the model since you are pushing down into the caulk.

I started out using the other (push onto object) method, because it seemed an easier way to make sure the top would be flat. I didn’t really think far enough ahead to realize that meant the bottom wouldn’t be. (Doh!) That’s easily be fixed by using the mother molds above, but you also have issues making sure the caulk is snug up against all sides of the item you are trying to cast.

You also don’t get that nice extra depth to the castings, which I’ve had some fun playing around with. It made the initial horse head much thicker and sturdier and makes it easier to get them out of the molds without breaking.

Hot Glue Molds

Hot Glue Mold Failure
Hot Glue Mold Failure

While wandering YouTube I found this video and figure it was worth a try. After all, I had the hot glue already because of the test with casting it (which was fun!) so what could it hurt?

My sculpey horse head. That’s what it could hurt. *mutters*

At high temperature the hot glue went on easily (as you can see from the fun I had building it up) but I still had to chase out a lot air bubbles. I had high hopes for it, although it was a lot more of a hassle than the caulk…

This was abject failure on all counts. The mold that was made had lots of defects in it, so the surface was far from smooth. When I was taking the sculpey horse head out it snagged a chunk of sculpey along the way. And when I tried to cast in it, it just made off with a bite out of that as well.

Fail, fail, fail. *dumps mold in trashcan* It might work better with ceramic or metal or plastic, like the ones shown in the video, but unsealed sculpey is a no-go.

Can you tell I’m still bitter that it broke my original? *sigh*


That’s all for now, but as I play around more (and hopefully get better!) you can expect a few more mold making posts to come… ๐Ÿ˜€

Martha Bechtel

My name is Martha Bechtel and I write fantasy and science fiction stories, paint small model horses silly colors, cast resin and plaster magnets, code random code (and Wordpress plugins)... Come on in and join in the fun!

This Post Has 5 Comments

  1. Me

    These look horrible. I would have thrown them away and be embarrassed to show them.

    1. Martha Bechtel

      I would normally delete spam comments like this one, but Iโ€™m going to leave it here to remind other readers that you shouldnโ€™t take mean spirited comments to heart.

      Making art is all about experimentation and learning, just because someone else doesnโ€™t like your end result doesnโ€™t mean that itโ€™s bad or that the effort was a waste. No one ever starts out being amazing at these sorts of things, it takes time, practice and experimentation to get to a point where you are happy with the results.

      You will always get comments like this popping up (especially on the internet) and learning how to ignore them is part of the process! ๐Ÿ™‚

      1. Joe

        At this point I just question why ppl even bother leaving these kinds of comments, if the owner can delete them and they don’t actually say how to do it better then it isn’t a very helpful comment. I also have to question why I bother posting these kinds of comments if what I’m saying is most likely ignored by most people, is totally irreverent to the main post, and it’s way to freaking long for all of my grammar/spelling to actually be correct, so probably gonna get some of them sweet grammar Nazi replies

        1. Joe

          Also I’m replying to a like 3 year old post so that’s helpful ?

          1. Martha Bechtel

            Old posts never die! ๐Ÿ˜‰ (But the blog owner does get distracted and replies late sometimes.)

            For a while I did delete the negative comments, but then it occured to me that I really should leave them in. Sometimes the only voice people have in life is online and if it makes them feel better to comment about what they hate as well as what they love… why take that away from them? It’s not like it hurts me, so as long as people aren’t over the top, I’m letting them vent. ๐Ÿ™‚

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