There are many variations on the recipes for slosh, but the key features are that it is soap based, and usually a foam.
I have also seen cornflour, glycerine and gelatine quoted as other useful additives, but haven't yet investigated these thoroughly. Glycerine (glycerol) however is commonly used as a foam stabiliser in cosmetics and is likely to do so in this application.
A further variation I have rarely seen is to dissolve soap flakes into boiling water with a small quantity of glycerine and food colour.
Key advantages of this type of mess are its quick clean up relative to gunge, natural opacity, relative low cost and ease of availability. These advantages see slosh persistently being used in the UK for theatrical use.
How to make
Before you start, It would be a good idea to read the general notes on the main gunge page.
You will need to obtain a traditional gentlemen’s shaving stick, which is relatively easily available from pharmacies/ drugstores or online. (Erasmic brand is well known and works effectively, but other brands will also be suitable). 1 stick makes approximately 1 bucket full, so if other quantities are required the recipe will need to be adjusted.
Start by grating the stick into a suitable container- a bucket would be appropriate. At this stage add any colouring you want- children’s poster paint works well, but food colouring is also possible.
Add hot water to the shavings- the stick will dissolve better in hot water rather than cold, so I would recommend using boiling water. You will need to experiment with the quantity dependent on the stick and how much slosh you want to produce, but a good starting point is to use ½ to ¾ litre of water per stick. It is possible to top up with further water as you mix, but obviously virtually impossible to remove it.
Whisk the mixture up to a foam. This could be by hand, but it will be much easier to use a food mixer, or even better a paint stirrer in an electric drill if making full bucket quantities.
If you want to use it immediately, then check that it is not too hot if you have used boiling water. If you are making up in advance you will find that the foam drains back relatively quickly (Within about 2 hours you will be back to the watery mix). You will therefore probably want to re-whisk just prior to use. You may also want to tip away any excess fluid as you see fit.
If left for a significant time (e.g. overnight you will find it very difficult to re-whisk to the original volume. Due to this, it is worthwhile making up the slosh relatively close to when you wish to use it.
Slosh away to your heart’s content!