whats causing this

[ljones]

i have been getting these blue patches all over on some pickled hides lately . it dosent seen to hurt anything but i cant figure out whats causing it  . i have been using the same pickling method for years  safety acid or McKenzie acid now and salt in a plastic container. anyone have any ideas ?

[Bowman]

looks like a pH strip or two got knocked over in the pickle.  They will leave that color mark...

[ljones]

i kind of thouht that to because it is the same color blue but this has happened on several batches of hides so i know it is not the ph strips scince i only use a very small piece to check the ph

[fishslayer13]

were they skins from the same person ?

[ljones]

nope  several different batches over the past several months

[Bucknut]

Does your plastic container have any blue in it? If it is recycled plastic there could be some residual dye that is leeching out with the salt.

[ljones]

i dont think so its  the same  black plastic rubbermaid container i have used to  pickeled skins in for several years

[misanoel]

Copper sulfate is a blue color.  Is is possible some chemical reaction is occurring?

[cyclone]

Copper sulfate is a blue color.  Is is possible some chemical reaction is occurring?

Yes, This is quite possible..

Check the cape(s) for copper bullet fragments.  There shouldn't be any detrimental effects however..

 http://en.wikipedia.org/wiki/Copper%28II%29_sulfate

[Bruce Rittel]

I think "misanoel" and "cyclone" are correct thinking it may a copper contaminate causing the blue discoloration. However, how is it exposed? Have you checked your Salt? Do you use something to weigh down your skins as they are pickling? Try changing the location of your vat - to avoid anything seeping down from your cieling that may cause it.

I think your acid can safely be eliminated. Copper bullet fragments could cause it, but it would be unusual to have it in several batches. Does this happen to only 1 cape in the pickle as opposed to all of them having the bluish coloration?

Try checking your Salt first. Is it 100% Salt (it should say it on the bag label)? Physically look at it. Could it contain contaminates? Do you use anything else when you mix your pickle, besides just Water, Acid and Salt? Any other additives?

[ljones]

Bruce i am not adding anything to the pickle  i have 4 other hides in the same pickle and they also have blue spots i am going to wash the container real good on the next batch and see if that helps. here is a picture of the salt i use the salt appears to be pure white salt no dark specks or anything.

[misanoel]

I'm putting my money on the anti-caking agent (yellow prussiate of soda).

http://en.wikipedia.org/wiki/Prussian_blue

Hope you're not generating Hydrogen Cyanide fumes.

[elkhunter1313]

You won't get that if you use KROWTANN

[Uncle Harley]

You won't get that if you use KROWTANN

UMMMM you use salt in the krowtan mix................ 

[misanoel]

Unless the Krowtann is strongly acidic, HCN probably wouldn't be an issue.

Here's another link:

http://www.chemicalland21.com/arokorhi/industrialchem/organic/SODIUM%20CYANIDE.htm

Can't imagine why anyone would want to feed this to livestock.