Casting in Silicone molds using Hot Glue

Hot Glue Casts in Silicone Molds
Hot Glue Casts in Silicone Molds

As you probably guessed from my Making a 100% Silicone Caulk Mold post, I’ve been happily dabbling in the world of ‘making art desks messy’ for a few weeks now.

So time to share what I’ve learned!

As I mentioned in the earlier post, I’m focusing in on the cheaper casting methods right now because I’m still in the learning curve. I’m not willing to waste a $20 resin kit, but I’m sure as heck willing to play with a $5 bucket of Plaster of Paris.

But first a quick dip into the Hot Glue casting, because I did play with this for a bit. As always, click to enlarge the photos (some significantly!) ๐Ÿ™‚

Casting using Hot Glue (High Temperature)

Horse Head Magnet Various Casts
Horse Head Magnet Various Casts

I saw a few videos on YouTube about casting with hot glue, but this tutorial finally convinced me to give it a try. I figured it would be nice to have a cast that wouldn’t break and that I could use for keychains.

The hot glue gun and glue sticks I used were picked up at Michaels, a high temperature mini, but otherwise generic.

On the generic note, I’d seen a bunch of videos on hot glue casting, but only started noticing the Mod Melts after the one above. Now I’m tripping over them every time I Google… I’m assuming it was the ‘blue car syndrom’ (Baader-Meinhof Phenomenon)

Mod Melts cost about twice as much as hot glue, so I dug up this video by Craft Test Dummies that determined there was no real difference between the two. So what follows can be used for either (in theory).

The Good, The Bad, and The Meh

Hot Glue Surgery
Hot Glue Surgery

The results were mixed– Since the hot glue is transparent and the molds I made were transparent, it was very hard to tell when the mold was filled. (As you can tell from the picture of the bird head going into for glue-surgery.)

There were some interesting tutorials about making colored glue sticks by mixing them with crayons, but I wasn’t impressed with the results from the clear.

There were also a lot of bubbles, even with the high heat and careful squishing into the corners. (Note: hot glue will not work with molds where the mold is narrower than the gun tip.)

Hot Glue Patch Job
Hot Glue Patch Job

The nice thing is it turns out you can just chop out the portion that is malformed, stick the remnants of the cast back in the mold and glue. The new glue fuses quite well with the old glue, but I found out the hard way that the old glue remelts the moment it touches the glue gun tip.

Which actually turned out to be a fun way to play around with a horse head that didn’t quite make it out of the mold alive. After some extra glue and some faux-fur doodling, it turned out a little silly, but cute. I have no idea what color to paint it, but it seems to take gesso quite well.

All in all, the hot glue was a fun experiment, but not much else. The glue isn’t sandable, hard to patch up (without sticking back in the mold) and prone to bubbles. It’s very flexible, so I have a feeling if I painted it without adding some sort of reinforcement it would be prone to cracking.

Hot Glue Improv
Hot Glue Improv

My molds are also very basic shapes, I don’t know how well it would take detail without getting too lost in the bubbles. There are a lot of tutorials out on YouTube that show some nice results, but I had so many issues with the bird and horse heads that I decided to stick with Plaster instead.

I may come back to this later, but for now… onwards! 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 4 Comments


    Please add me to your email list. Thank you.

    1. Martha Bechtel

      Done! Sorry about that, I didn’t realize the link in the sidebar had been removed during the reorg. ๐Ÿ™‚

  2. Anonymous

    Do not use it on high it will melt your mold

    1. Martha Bechtel

      I’ve seen people cast aluminium in silicone caulk molds in videos before, so I didn’t think a hot glue gun could hurt them. What sort of melting did you see happen with one? ๐Ÿ™‚

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