There are many other recipes for making goo, both on Instructables and other places on the web as well as commercial products, so why use this one?
You enjoy making things and you will probably learn something new whilst making this
The cost will be significantly cheaper than buying a commercial product
You have full control of the properties of the goo- from runny to thick, clear to opaque and colourless to vivid colours
You can happily make large quantities of goo- even filling a bath or paddling pool becomes practical (think how many tubs of toy shop slime you’d need to this, or how much PVA glue)
The materials are easy to store- you can easily keep some on hand for rainy day play, or next Halloween
The gunk is a bit sticky- it therefore has a much better feel, and visual appeal than some commercial products (like Gellibaff), that simply run off.
The materials are biodegradable, and hence easy to dispose of
Most importantly- it’s more fun than buying it!
Whilst the materials on this page that are not known to have any significant health risks associated with them, they cannot all be classed as completely hazard free.
The largest single issue is the slipperiness of the mix- it can be very easy to slip over on. It is therefore essential to consider this when planning any activities involving slime, including clean up and washing off as the most significant effects will be found on a smooth surface such as a bath!
The materials are relatively fine powders, and as such create nuisance dust. It is therefore worth wearing a dust mask if handling large quantities. Likewise if this dust gets into eyes it can cause irritation.
Guar gum is not hazardous when eaten, however it can be used as a laxative, so it would probably be unwise to consume large quantities.
Borax (Sodium Tetraborate) is not safe for consumption, and should therefore be handled and used carefully so as to avoid ingestion, although in the quantities actually present in slime it should not cause any concern.
It is worth noting that whilst some other recipes found on the internet claim to be borax free, this isn't always the case. those recipes that use laundry starch have borax in the starch.
In addition to the specific information above, general safe chemical handling practice will further reduce the risk of any issues, in particular;
Store materials in sealed, well marked, containers in an area out of reach of children and pets
Wash thoroughly before and after handling these materials
Dispose of excess/ used materials/ empty packaging responsibly
Clean up any spills quickly- Avoid using water to stop the area becoming slippery
Do not use utensils/ containers/ cleaning cloths that will be later used for food
Supervise children whilst making or using the slime
In these instructions the quantities I give will make 1 litre of stringy slime. Quantities can therefore be easily adjusted to suit smaller or larger batches to suit your needs.