Home Cosmetic Science Talk General Making a Giant Slab of Soap

  • Making a Giant Slab of Soap

    Posted by Bubica on January 22, 2021 at 2:52 pm

    Hi there,

    I have been lurking here from time to time, and I really liked some of the production upscaling advice you guys had so I thought I’d give it a shot.

    I am planning to make a 300kg soap slab for an art project. My biggest batch so far has been 2kg, so I am in way over my head. As of now I don’t have access to any industrial size production facilities, so I am going to have to wing it somehow. 

    There are two different recipes I am considering.

    One is cold process formulated with coconut and lard. It would make for a hard and durable slab that would not need to cure much. This is important cause it will spent the summer outside in sun and rain. The biggest problem for me is how to melt all the fat so that it can be stirred to emulsify when lye solution is added. Where I live summers are cold and wet, and only a couple of days a year the solid oils and butters will liquify. 

    How would I pour this giant drum of alkaline sludge into the mold? I would like to do the pouring directly into a mold atop a trailer and drive it to the site to unmold as to prevent damage.

    I guess one of the options would be to make smaller batches and just pour them atop each other, but I guess there would be visible imperfections on the surface… Maybe that is fine, too, as it would not be visible for long as I intend for people to use it.

    Another recipe I’m considering is for a high temperature hit process transparent glycerin soap which could be made to be remeltable. This way I could do smaller batches, but how would I remelt all that and pour it fast enough before the previous pour solidifies? This method would maybe not look so great done in layers, as the boundaries would be visible, the soap would be softer and maybe less durable. But maybe it would be more interesting as it ages under the influence of the elements and people…
    I would have access to a budget that would cover things like one of those concrete blenders or such equipment, induction cooker and big pot or such.

    Everything about this is scaring me right now, but it is also exciting. I welcome all suggestions, questions and ideas :)
    Thank you for your time
    Benz3ne replied 3 years ago 3 Members · 2 Replies
  • 2 Replies
  • EVchem

    January 27, 2021 at 11:40 am

    Why not pump it into the mold while hot? If you can get ahold of a diaphragm pump you can pump directly from a steel drum with heat bands (or big pot you heated up)  that you could have an overhead mixer going on. That should be a relatively cheap way that still makes sure you have uniform product

  • Benz3ne

    January 27, 2021 at 12:54 pm

    One thing I’d be mindful of is environmental regulations. They’re not typically keen on large quantities of soap or surfactants ending up in water streams.
    Fish don’t get on with them (understatement).
    Sorry to bog down what otherwise sounds like an interesting project.

    As EVchem mentioned, you could look into a 205L metal drum and a heated drum jacket, perhaps? Just worth checking that the drum is suitable for lye and you should be good to go. I used to use a large, electronically-heated pot in work for natural glues/gums (not cosmetic related fwiw) and that could probably hold around 50L total and was on a stand so it was pourable. I’ll try and find an example of something similar…

    Edit: found one. We referred to it as a ‘kettle’ which is as described here. No affiliation with the company or product, etc. https://taizyfoodmachinery.com/jacketed-pan-jacketed-kettle/
    The above one is steam-powered which seems to be more favourable these days and even comes with a mixing motor so that’d be useful for bulk mixing of lye and oils/waxes, especially for cold-process.

Log in to reply.