Blue dots on veg tanned leather

[Bodean]

Has anyone else had blue spots appear on veg tanned leather after casing?

They seem to appear randomly. I had a piece that i did recently that did not have spots after I cased it the first time. I had to recase the piece because it dried out some and a spot appeared.

This isn't the first time this has happened to me. i am just using distilled water for casing. I did switch brands and same difference.

It looks like a blue dot from a ball point pen. Some are bigger than others at times.

I wouldn't complain, but the piece I am currently working on is going to be natural not dyed.

[Matt S]

Sounds like iron filings have come onto contact with your leather from somewhere. The iron reacts with the tannic acid to form iron tannate, which is an insoluble blue-black lake. It's the same effect people seek out when striking with vinegroon. Application of lemon juice to the spot should solve the problem.

[Bodean]

I thought I would post a picture.

 

[Northmount]

Definitely iron contamination.  Keep all iron fillings, etc. out of your leatherwork area.  Oxalic acid will remove the spots.  There are a number of threads about these spots if you want to search out more information.

I would recommend that you be careful trying to bleach out small spots as that spot may now become lighter than the rest of the piece you are working with.  I would do a quick bleach of the whole surface to try to maintain consistent colour across the item.

Tom

[Bodean]

1 hour ago, Matt S said:

Sounds like iron filings have come onto contact with your leather from somewhere. The iron reacts with the tannic acid to form iron tannate, which is an insoluble blue-black lake. It's the same effect people seek out when striking with vinegroon. Application of lemon juice to the spout should solve the problem.

Thanks for the reply. What you say makes sense. Are you saying put lemon juice on the spot?

[Bodean]

2 minutes ago, northmount said:

Definitely iron contamination.  Keep all iron fillings, etc. out of your leatherwork area.  Oxalic acid will remove the spots.  There are a number of threads about these spots if you want to search out more information.

I would recommend that you be careful trying to bleach out small spots as that spot may now become lighter than the rest of the piece you are working with.  I would do a quick bleach of the whole surface to try to maintain consistent colour across the item.

Tom

Thanks for the reply. I will try that.

[Bodean]

I tried some lime juice first. It is slowly disappearing after second application. Hopefully one more time will do it. Thanks for the help guys.