Our product this week is tannin, which can be used for multiple things such as:
*facial astringents *leather tanning *medicinal purposes
Tannin is an astringent, meaning it tightens pores and draws out liquids.† It is a molecule found in plants, like tree barks, which bonds readily with proteins. When you apply these tannins to your skin you can instantly see the skin contract (astringents are often used as a face cleaning product). †If you put tannins in your mouth, your cheeks will pucker.† Medicinally, tannins are used to draw irritants out of your skin such as the venom from bee stings or poison oak. Next time you get stung, pull some fresh bark off the twig of a nearby tree, chew it up and apply it to the sting. The irritation will go away within seconds. Tannins are also applied to burns to help the healing and to cuts to reduce bleeding.
††††††††††† There are two main types of tannins:
1.† Catechols (or condensed) are more astringent and tan quicker than the other. They deposit a reddish sediment known as 'reds'. They make leathers of pink, red or dark brown hues that are more 'solid'. They also create greenish-black spots on contact with iron. Mimosa, birch, hemlock, quebracho, alder and fir bark contain catechols. Oak bark contains both types.
2.† Pyrogallols deposit a pale-colored sediment called 'bloom' (an elegiac acid) which, if deposited in the leather, improves its cohesion, wearing properties and resistance to water. Hence they are favored for sole leather. They are also preferable for leathers intended for bookbinding, upholstery and other purposes where longevity is essential. The resultant leather is of pale color varying from creamy or yellowish to light brown. Pyrogallols make bluish-black spots on contact with iron and resist changes in pH value. Sumac, chestnut, oak galls and oak-wood contain pyrogallols.
Collecting: All barks are best collected in the spring when the sap starts to rise in the trees, the leaves are just coming out and the bark will peel easily (a fortunate coincidence). This is when they are most concentrated and the easiest to peel, but you can still use bark from any time of year. Tannin is usually concentrated in the inner bark (cambium layer). Supposedly, an older tree has more tannin than a younger one, and the lower parts of the tree contain a higher concentration than the top parts. One source says that fir trees should reach 30 years old before debarking and the best oak trees are between 15 and 30 years. Another source said oaks are best between 30 and 35 years...so I wouldn't get too caught up in it.
Shredded bark from sawmills sold as garden mulch is excellent for bark tanning (as long as it hasn't been left out in the rain too much).
How Much: It really depends on the quality of your source. Mark Odle suggests that in general it takes about twice the weight of the hide in bark to create a good tan.
Storing: Bark should be dried out and stored in a dry place. Tannin is water soluble and will be leached out of wood or bark that has been left out in the rain. If kept dry, it can be stored indefinitely without losing its effectiveness. Bark is easier to grind down if itís dry too.
The bark will need to be ground up into corn size parts, the smaller you can get it the more tanning agent you will get.† Then soft water is required, rain water will do best.† The minerals in other water will react with the tannic acid to form spots on the skin.† The hide will still tan without soft water but the quality will be worse.†
Fill kettle halfway with bark and totally full with water. Bring it to a boil and let it boil for at least an hour. Taste it. The more bitter and astringent the more tannin...like tea or coffee. Take half the liquor and mix with equal amounts of water for the first bath and use a tub.† A wood tub is suitable and wooden stirring paddles should be used.