[JamyKate (OP)]

Hello to any chemists out there.

I hope you can help with my query. I spin fleece into yarn, and am progressing onto dyeing my yarn with natural dyes.

One of the mordants (chemical to help the dye to stick to the wool) I want to use is Alum. I managed to get some via a local Pharmacy, but now I've received it, I'm not sure if it's actually the thing I'm after.

On the box it says: 'Alum (Potash) Ph Eur'. It's in the form of clear tiny beads (granulated?).

When I look at examples of Alum on wool-dyeing related sites, it seems to be a white powder, and is either described as:

'Potassium Aluminum Sulfate' newbielink:http://www.wwwearables.com/natural/mordants.htm [nonactive]

'Aluminium Potassium Sulphate'. newbielink:http://www.fibrecrafts.com/ProductDetail.asp?Level1=1&Level2=16&Level3=0&PID=4512&Action=&FromPage=1 [nonactive]

Do I have the same stuff?  []

Many Thanks for any help you can give.

 

[Bored chemist]

You will no doubt be pleased to know that you have the right stuff.
Part of the process of purification to get it up to European pharmaceutical grade involves crystallising it carefully. (Essentially a lot of the impurities don't fit properly into the crystal so they get left behind in the solution.) This gives a nice product but is expensive. For commercial materials like mordant there's less incentive to get it all that pure so they don't take so long crystallising it and get a crude powder.

[JamyKate (OP)]

Bored Scientist,

Many Thanks for your reply. I can now go ahead with my dyeing without fear of killing myself by boiling up something I wasn't sure of!

[lightarrow]

Bored Scientist,
Many Thanks for your reply. I can now go ahead with my dyeing without fear of killing myself by boiling up something I wasn't sure of!

Did you know alum it's a "mordant" for blood too? It's used to stop little wound's bleeding, after a shaving for example. You friction a cristal of alum on the wound for some seconds and then it stops bleeding. It's sold in pharmacies or ...(actually I don't remember where I bought it, a lot of times ago... [])