Making molds

[Kittish]

An update on the plastic mold liners- They didn't work out nearly so well as I'd hoped they would. For the first few uses they were great. Then they started warping, and leaking and the soap started sticking to them really badly. I'm thinking the lye was attacking whatever kind of plastic they're made from, and the packaging for the cutting mats didn't indicate what it was.

I'm shifting over to silicone molds. I've got two 500 and 3 750 gram loaf molds as well as a 750-1000g small slab. At the moment, I've got cardboard sleeves on the ones that need support. I've got a pallet with slats that are 1/4" thick, I'm planning on salvaging those and reusing what I can from my original molds to build permanent boxes for them. The parts of the liners that are salvageable I'll use as stiffeners in leather projects.

Here are the original pics again, since the links are broken above:

 

[penelopejane]

At least you will find it easy to make the new molds to go around the silicone liners with all that practice!

I got Nurture liners. They are thick and work well. They are really shiny inside and work well but I've only made about 20 batches with them. They unmold as well as the first time.

One thing I learnt is it is good to have one end that is removable (wing nuts and a bolt etc). Since I've modified my molds I haven't needed to take them apart so maybe making them 2mm longer than necessary would be enough, not sure.

 

[Kittish]

I will keep that in mind when I start building the next round of boxes. Long bolts aren't hard to come by.

 

[BattleGnome]

Have you seen the Soaping101 silicone mold video? She makes a cardboard box to tightly fit the wooden mold then paints the cardboard with silicone to make the liner. Maybe you can still use the ones you've already made (provided you haven't invested in something else already)

 

[Kittish]

Have you seen the Soaping101 silicone mold video? She makes a cardboard box to tightly fit the wooden mold then paints the cardboard with silicone to make the liner. Maybe you can still use the ones you've already made (provided you haven't invested in something else already)

No, I haven't seen that video. I've got my smaller silicone loaf molds already (except you can never have too many, right?) but I've still got the 4 pound wooden molds I bought off etsy and the big deep square box I built (looks like it'll make 8 or 10 'on end' bars and is plenty deep enough for that). I've got silicone baking mats to try to make mold liners with, as well as teflon heat transfer sheets. If neither of those work out well, I may get a tube or two of silicone caulking and try painting some cardboard. Huh, now that I think of it, I may get some and see if I can make a drop in divider for that big box. Easier to work with than trying to cut acrylic probably.

 

[penelopejane]

^^ they don't use the same silicone as silicone caulking.
Watch one of the videos.

 

[Kittish]

^^ they don't use the same silicone as silicone caulking.
Watch one of the videos.

You're right, she isn't. For the mold liner she's using liquid latex rubber (which does check out as lye safe). Hmm. I bet silicone caulk would work, too. I might have to try them both, just for the sake of comparing. I see though that it wouldn't work for a drop in divider for my big box.

Here's the video for anyone else who wants to check it out, too: [ame]https://www.youtube.com/watch?v=GKClapkhZxo[/ame]

 

[0115d8cf]

Sorry to hear, but I'm glad you posted an update! That is some serious diy

 

[penelopejane]

There are others who've use silicone - just a different type of silicone - google soap liners.

I think it's the heat that the other silicone is better for.
But it's $$$. So really think if you might not be better off with a quality silicone mold and make the surround.

Aliexpress has lots of cheap silicone molds but most have a lip at the top which means you'd have to be restricted to that height or cut it off so you can have a lid.

BB molds would be a pain to make a box for. Nurture are easy.

 

[Kittish]

There are others who've use silicone - just a different type of silicone - google soap liners.

I think it's the heat that the other silicone is better for.
But it's $$$. So really think if you might not be better off with a quality silicone mold and make the surround.

Aliexpress has lots of cheap silicone molds but most have a lip at the top which means you'd have to be restricted to that height or cut it off so you can have a lid.

BB molds would be a pain to make a box for. Nurture are easy.

I've got several silicone molds already that I just need to build boxes for, and I'm sure I'll get more. I'm pretty much going to shift to silicone entirely for my day to day soap molds. I've already disassembled most of my first shot at boxes to use to make those surrounds. It's just the two big loaf molds that I got from etsy and the big, deep square I made that I need custom liners for. And I'm not opposed to trying out different methods and materials until I find the one that I like best.

 

[0115d8cf]

You're right, she isn't. For the mold liner she's using liquid latex rubber (which does check out as lye safe). Hmm. I bet silicone caulk would work, too. I might have to try them both, just for the sake of comparing. I see though that it wouldn't work for a drop in divider for my big box.

Here's the video for anyone else who wants to check it out, too: https://www.youtube.com/watch?v=GKClapkhZxo

Silicone caulking is great for smaller push molds, but I can't imagine painting with it. It's gloppy and thick and sticky, unlike the pourable latex.

And it reeks. Bad.

 

[Kittish]

Silicone caulking is great for smaller push molds, but I can't imagine painting with it. It's gloppy and thick and sticky, unlike the pourable latex.

And it reeks. Bad.

That it does. I've used it before for other projects. If you use a nice, wide flat brush, it can be spread to a thin, relatively smooth layer.

The latex she uses in the video isn't very pourable, I don't think. Looked like rather thick paint. I'm going to get a jar and try it, as well as trying the silicone caulk idea. I might also try one or two of the two part silicone mixes (you can get them in different hardnesses, from super soft up to very firm) and see if they work at all for painting thin layers. I will post pics of each attempt as I make it, though it'll probably take me several months to work my way through them- I have rather a backlog of projects in progress just now.

 

[penelopejane]

That it does. I've used it before for other projects. If you use a nice, wide flat brush, it can be spread to a thin, relatively smooth layer.

Here's another video on making a silicone liner for a soap mold:

[ame]https://www.youtube.com/watch?v=xr3q5D6qDRc[/ame]

 

[Teapot]

Both really useful videos, thanks for linking those.

I'm currently using silicone sheets to line my wooden moulds, but they are in separate pieces, so there is a tiny bit of leakage at the corners. Not much, but obviously over time it's not going to do the wood any favours, so I want to make silicone liners to fit the moulds. And if I make multiple liners, then once the soap is solid enough, I can lift it out and re-use the mould, rather than having the whole thing out of action.

In case it helps anyone, I rub vaseline along the wood and then stick the silicone sheet to that, so that it doesn't flop and sag.

 

[deighturp]

I line my wooden molds with parchment paper and after the soap sets up I just lift if out of the mold, and cut the bars. No problem (yet) and I think there won't be any problem in the future.

 

[amd]

Yep, I do the same way too with freezer paper. I have made cutting mat liners and used them a few times. I have to put in the freezer before pulling off from my soap, but I do really like them.

 

[earlene]

Silicone caulking is great for smaller push molds, but I can't imagine painting with it. It's gloppy and thick and sticky, unlike the pourable latex.

And it reeks. Bad.

To paint with the silicone caulking I used a method that includes adding naptha (purchased at Home Depot) solvent into the caulking. This makes it 'paintable'. It smells to high heaven for a really long time and I'm not sure how long it actually takes to dissipate. I learned it from a guy who makes masks, so my granddaughter and I did it for her Hallowe'en costume one year.

If you want to give it a try watch this video. If you skip forward to minutes 9:01 that's where he starts mixing the silicone caulk with the Naptha then he goes on from there to paint the mixture onto the form.

[ame]https://www.youtube.com/watch?v=vfH_HCI0G4I[/ame]

 

[bathgeek]

So here's a question... why don't we just paint the inside of wooden molds with silicone? Is there a reason this isn't a thing? Does the silicone mold absolutely have to be separate from the wood? I'm thinking of making a box with a front that flips down, and if I coat the whole thing with silicone on the inside then once I flip the front down I can theoretically slide the whole thing out the front, then just wipe down the mold and reuse. What am I missing?

 

[Kittish]

So here's a question... why don't we just paint the inside of wooden molds with silicone? Is there a reason this isn't a thing? Does the silicone mold absolutely have to be separate from the wood? I'm thinking of making a box with a front that flips down, and if I coat the whole thing with silicone on the inside then once I flip the front down I can theoretically slide the whole thing out the front, then just wipe down the mold and reuse. What am I missing?

That sounds like a very good question, actually. I have to wonder if it would work. *adds another idea to the list to try*

 

[Teapot]

I have wondered the same, about painting the inside with silicone. Logically, it seems like it should work, but I wonder how easy it would be to get the soap out? (If the mould doesn't have any removable pieces, that is.)

I find that if my silicone pieces fit together very neatly with no gaps, it's hard to get the soap out of a straight-sided loaf mould. When I use the fractionally larger mould, there is a 1-2mm gap where the liners don't meet, and it is much easier to get the soap out. (To clarify, I have two wooden loaf moulds, but one is about 2mm longer than the other.)