Help my silicone loaf mould shrunk.

[avster]

Hello community! So glad to be a part of this forum!
I'm fairly new to soap making and bought these loaf moulds that are meant to be used without wooden casings on the outside.
I've made 2-3 batches of soap and I noticed the shape of the soap changing..the bottom remains nice and straight but the top has started to warp inwards..this makes the soap look wide at the bottom and thin at the top!
Any suggestions what I could be doing wrong?
Attaching a photo of the moulds warped up in comparison to a non warped mould and also a nice of the soap from a warped mould to show you how the shape of the soap is not a nice straight rectangle!

 

[not_ally]

You're likely not doing anything wrong, those are probably just not the greatest molds. They look fairly thin, which means that they are likely to be floppy and produce bars that are not straight, like the ones in your photo. The only way I can think of to address this is to buy or make some kind of support for the one that hasn't warped yet. See, eg., https://www.soapmakingforum.com/threads/lightweight-inexpensive-insulating-box-for-soap-molds.85953/

Or just buy sturdier molds, if you can, or ones with wooden frames/boxes.

ETA: This is a thread from several years ago about Indian soap making suppliers, not sure if contains mold info, but there might be relevant or otherwise helpful/useful info if you read it through:

https://www.soapmakingforum.com/threads/soap-making-ingredients-suppliers-in-india.82865/

 

[avster]

You're likely not doing anything wrong, those are probably just not the greatest molds. They look fairly thin, which means that they are likely to be floppy and produce bars that are not straight, like the ones in your photo. The only way I can think of to address this is to buy or make some kind of support for the one that hasn't warped yet. See, eg., https://www.soapmakingforum.com/threads/lightweight-inexpensive-insulating-box-for-soap-molds.85953/

Or just buy sturdier molds, if you can, or ones with wooden frames/boxes.

Thank you so much for your response!
I will definitely try to do the support for the mould method!
So nothing can be done with the one that's warped?

 

[Sudds]

If you can find big paper clamps to hold them next to the edges of a box that you can make out of thin plywood...use wood glue to hold it together they will stay straight sided.
I bought two of the "not so perfect" Nuture's silicon 7.5# mold that is crazy thin (that is why it is not so perfect!) because I wanted to see if I was capable of make larger batches of soap before investing in bigger molds. I made my boxes out of 1/8" plywood and then found some big paper clips and clipped the sides of the silicone mold to the box and it worked great, you have to remove them before you get to the top so you can decorate your soap but the mold won't collapse in because the soap is heavier than the mold sides. I wouldn't recommend doing this normally but for an experiment it worked great for me. As caution, I would recommend always have a box that will hold your silicon molds, silicon isn't hard enough to stand on its own. When I was working on my April challenge I had to scramble to find a piece of wood to place my molds on because they were so soft I knew I would not have been able to move them off the counter to even wrap them!

 

[akseattle]

So nothing can be done with the one that's warped?

@avster , I have had a problem with some single cavity silicone molds that have bought. The silicone itself is probably 1/4" thick but very soft and floppy. i could see they were slightly mis-shapen the day they arrived. So, an oval was not oval, a rectangle kind of caved in - like your mold. If your mold has actually shrunk, I don't know what can be done.

But, if it's only just warped, not shrunk, could you try to rig up a means of holding the sides out- at least until the soap firms up a little.
On one of mine, I first tried to hold the sides out by putting the mold in a little box and then taping the sides to the box. But, nothing sticks to silicone!

One of my floppy round molds (really cute with a baby sleeping on the moon) fit perfectly into an egg ring. So, that egg right helps it keep its round shape and doesn't cave in.

I don't have a science or chemistry background so you might just ignore what I'm saying. But, I'm wondering if you can get a wooden box for your warped mold, then boil the warped silicone mold in water. I assume it will heat up and soften??? If it does, you can put it into the wooden box until it cools off to see if it will re-shape itself. Hopefully, the worst is that your mold will be permanently no good, but that you won't blow up your kitchen or something I don't know if warmed up silicone gives off dangerous fumes. Maybe you can see if you can find something about that?

 

[Mobjack Bay]

If you’re not making high top soap, you can use spacers to hold the walls out. Something like this, made from straws and coffee stirrers:



ETA: Did you put the warped mold through the dishwasher? If so, I would avoid that in the future. Here’s one thing I would try with the warped mold. Let it soak in very hot water to soften up and then put a premade cardboard form in to hold to hold the correct shape as it cools off.

 

[AliOop]

I’ve seen Ione (of Eve’s Garden Soaps) use Vaseline to stick the outside wall of the silicone to the inside wall of the wood mold. Seems to work pretty well for her.

 

[ScentimentallyYours]

My molds look the same because they stretch when I pull the soap out. In short, the sides get floppy. I use clear tape at the very to of the silicone mold to secure it to the wood box, 2 pieces on each side. The silicone mold still fits the box fine when taped. You’ll need to cut the tape or remove it to take the soap-filled silicone from the box.

 

[Mobjack Bay]

As the OP mentioned, their mold is the self-supporting type (with the vertical ribs on the sides), not a silicone liner in a wood mold.

 

[akseattle]

Tape didn't work for me on single cavity molds. It just slipped right off.
My single cavity molds are too shallow for spacers (most are 1" or less tall), I think anyway. @Mobjack Bay did you make that spacer out of something or are those spacers sold somewhere in various sizes? The spacer approach has given me the idea of bending the prong from prong paper fasteners (I have zillions...) to make a brace ( like an upside down square U") for my floppy single cavity molds. I think the prongs are aluminum, so this would not work with cold process soap. But for Melt & Pour, I think this would be safe?

 

[Mobjack Bay]

@akseattle I made the spacers by cutting sections of a milkshake/slushy size straw (large diameter) to the right length and then added the coffee stirrers as supports.

 

[akseattle]

I made the spacers by cutting sections of a milkshake/slushy size straw (large diameter) to the right length and then added the coffee stirrers as supports.

Wow, that is a really simple and workable idea (and looks totally pro from a distance!)
I enlarged your photo and could see how you did that. I think it will work with my single cavity molds, too, for cold process even since no aluminum.
They may have a small dent along the center bottom , but they wouldn't be mis-shapen. Thanks for the tip !!

 

[ScentimentallyYours]

As the OP mentioned, their mold is the self-supporting type (with the vertical ribs on the sides), not a silicone liner in a wood mold.

I did not see the ribs! The first time I looked quickly at the picture. With silicone molds that don’t have a box, my problem is with them expanding out in the middle. I use tape to stop that, too.