Is Chrome Alum and Potassium Alum The Same?

[LFLarry]

I have a formula that calls for Chrome Alum as a hardener.

I have some Potassium Alum on hand and I wanted to check if these two chemicals are effectively used for the same purpose?

Thanks in advance.

Larry

[Vaughn]

I believe the Potassium Alum (potassium aluminum sulfate) will act slower than the Chrome Alum (Chromium(III) potassium sulfate).

I have only used it on its own (not in a formula) as a gelatin hardener and help clear carbon prints.

[Tin Can]

One more question

Is Food Grade ALUM as bought in US stores, usable as hardener?

I tried it once with J Lane Plates, but couldn't tell and stopped.

[Nodda Duma]

Chrome Alum and Potassium Alum are not the same.

While they both harden, chrome alum works faster and also aids adhesion to glass.

[LFLarry]

Thanks for confirming. It seems that Chrome Alum is a little hard to come by at this time...

Anyone know of a source in the USA that has some in stock?



Chrome Alum and Potassium Alum are not the same.

While they both harden, chrome alum works faster and also aids adhesion to glass.

[Vaughn]

One more question

Is Food Grade ALUM as bought in US stores, usable as hardener?



I quickly checked via google -- mixed answers...seems to be confusion as to what Alum is!

[koraks]

Food grade will be generally potassium alum or otherwise sodium alum. Both should act as a hardener, but you'll need more of it than chrome alum to reach the same degree of hardening, or hardening time needs to be extended. A friend of mine used food grade alum for making hypo alum toner, which worked fine. Different qpplication of course!

[Jim Michael]

Sigma Aldrich carries it. This is th 98% grade https://www.sigmaaldrich.com/catalog/product/sigald/243361?lang=en&region=US

[Tin Can]

Thanks for the responses

Food Grade is found in the baking section at my local Kroger

Online they add it is Kosher and good for dying fabrics!

$1.99 can 2.37 oz UPC: 0001111000309

As a child I was given chunks of Alum for mouth cold cores, yet haven't that problem since