Caffeine in a Tannic Acid Solution from Tea

[Gosut]

This is odd, but was thinking about tea for a tannic acid bath for dyeing, and happened to think about caffeine. Even decaf tea has some caffeine, so it's not caffeine free. That means a tannic acid solution made from tea will have caffeine.

Why worry about it? Because caffeine can be absorbed through the skin. That wouldn't be an issue where the item isn't worn on a person. But there's been times in the summer than my belts have become soaked in perspiration, not to mention leather watch bands back in the day. What would this mean for caffeine absorption through the skin? 

[chuck123wapati]

veg tan leather already has tannic acid in it that's what tans it, you don't need a tea bath. I do use it for staining wood with vinegaroon but even then i wouldn't worry about it in the slightest.

[chuck123wapati]

i was going to dye a piece of leather with roon but this is better . My roon dried out lol all that is left is the iron oxide i took a pinch smashed it  between my fingers and sprinkled it on a piece of leather then just a spray of water dyed the leather instantly. Its just the reaction between the iron and the tannic acid already in the leather.

[fredk]

Its not the caffeine; tea has tannin in it. So does coffee, but less so. The better quality of the tea the more tannin.

Ever drunk a cup/mug of good qualty tea and had a dry feeling in your mouth afterwards? that is the tannins working

[Gosut]

Yes. The iron acetate reacts with tannic acid to make the black, and that's why tea is often used as a pre-vinegaroon treatment. It's convenient and low-cost. For blackening leather,  the caffeine isn't important, but is still there, along for the ride. My concern is absorption though the skin is a situation where the leather becomes soaking wet, as with perspiration or rain, and is essentially against the skin.

[chuck123wapati]

Caffeine isn't harmful in the amount your talking about.