Can you suggest a method?

[kaseencook]

I currently make silicone liners for wooden moulds (for soap), by pouring a sheet of silicone and welding the four walls and base together with silicone.

This is what they look like (scroll down): (http://www.tortugasoaps.com.au/moulds.html)

The end product is good and strong, but it is a messy pain in the bum to put together and very time consuming.

I would like to pour the silcone into a mould shapped like the liner, but have not been able to find a material that works to make this box like mould.

The liners walls are 3mm thick and about 52mm and greater tall, so it is a very tight space, and plaster moulds are impossible to demould without destroying the plaster. I need a mould for my liners that comes apart for easy demoulding, has smooth inner surfaces and sharp corners, and can be used multiple times.

Any construction, rig and/or material ideas would be GREATLY appreciated! Cheers!

[ALpmc]

You have the right idea, you just need a female mould box and a male mould (core) that would be perfectly suspended into the female half with supporting cross bars set on alignment pins protruding from the top edge of the female mould. Then you pour your silicone between the two. As far as a material, milled plastic would be perfect! No release agent required. Wood is the reasonable alternative. With wood you will have to seal and sand. Then prime with sandable automotive primer, wet sand, repeat several times on both male and female moulds. Then wax and buff. You should still use a release before each silicone pour. A little time consuming, but you would only have to do it once for each size you plan to manufacture.

[rowbare]

Check out http://www.freemansupply.com/
They have a bunch of videos that might serve as inspiration.

[kaseencook]

Thanks for the ideas! I'll give em a whirl.

And thanks for the link, checking it out now, looks like there is lots of good info!

Cheers!

[One of Many]

That does look like a pain peeling the silicon liner off every bar. Is the only benefit to using one piece type of liner the softer radius on the moulded edges or leakage? What temp is the soap in liquid form.

If you had the equipment to machine or cut and bolt together a square ring of HDPE or even LDPE, then bolt that ring to an aluminum plate covered with a sheet of silicone. That could be your mould. You could have several moulds on a plate.

The square rings should have a slight bit of reverse internal draft(.5-1deg) so that once the soap hardened, unbolt the ring and push the block of soap out the bottom of the ring. Bolt the ring back in place and it is ready to go again. High and low density polyethylene has a waxy surface, so your soap shouldn't stick to it. If the corners didn't need to be square, the rings internal shape could be milled with an angle cutting endmill in one piece rather than bolting strips together.

You could do the same with silicon rings moulded with an internal skeletal structure that helps it retain its shape and allows it to be bolted to the plate for a good seal. Or just sheet liner wood rings with a separate(removable) lined bottom.

Depends on the properties that silicon gains you, verses other materials and slight changes to make them work with less hassle than the silicon liners.

DC