How do you tan fish skin?

Answer 1

In researching the topic of tanning fish skin. I have noted that the tanning of fishskin is not much different from the tanning of most other leathers. Remove the fat, meat, and scales. Then treat with a curing substance. One company uses plant based curing agents, though the process is kept a secret. A full compilation of various fish skin specific tanning methods should be established here.

Taken from http://poorbuthappy.com/yourthing/post/rare-information-on-tanning-fish-skinsobstruse---by-eskimo-woman/ :

Traditional Eskimo Fish Tanning Method

Urine tanning chemistry
Within the leather trade, urine has been used for dehairing skins, for
tanning skins and for washing skins.
Urine contains formic acid and urinase, and uric acid, among other things.
These acids have a preservative effect on the skin.
When urine is left to stand ammonia is formed, which is a strong base. If
a hide sits in urine for some time, the basic environment will begin to
have a dehairing effect.
The ammonia influences the skin by splitting the naturally occurring fats,
to form glycerol and free fatty acids. These free fatty acids can
penetrate the hide and react with the fibers of the dermis; the skin is
tanned. When ammonia is used as a cleaning liquid, it is it's saponifying
properties that are being exploited.

I have made a few tries at urine tanning of fish skin. The recipes I
started with come from Rita Pitka Blumenstein, who lives on Nelson Island
in southwestern Alaska. She relates the following:

"Fishskins were used for mukluks, mittens, water carriers, and
raincoats....The king salmon is used for boots, heavy-duty boots. Only
female silver salmon is used for hats for girls. And the pike skin is for
water jugs. The trout is for bags....
"You take the skin off and soak it in the water, and then you scrape it
with a sea shell. Some fish you have to scale; some fish you don't. Like
pike and white fish, you've got to scale it, you soak it in urine. The
urine has to come from a young boy baby before weaning. It doesn't contain
any chemicals, just momma's milk. For thicker skins, you have to use the
urine from an older boy, around the time his voice changes.
"[The skin soaks in the urine] sometimes half a day, sometimes overnight.
The longer you soak it, the softer it gets. Then my mother used to
use[Fells] Naphtha soap, and she sudsed it in the water and then cooled
off the water and then put the skin in it. Then she puts aspen shavings
in the water and cools it off, then you rinse it in clear water and wring
it out. My mother used a towel to absorb the water. I asked her one time
in camp, 'What did you use when you didn't have cloth?' She said they used
dried moss. And then you put it on a smooth board, stick it there, the
inside facing in. Then when it dries, it will just peel off itself. You
store it away, and when you are ready to use it, you wet the shavings that
you saved, and you pad them onto the fishskin on the outer side. Then you
roll it and leave it until it dries. Then you shake it off." [Hickman
1988: 19ff.]

I have started from this recipe but have used woman's urine for 10-12
hours and then rinsed the skins, washed them in water with soap, laid them
in a willow bark bath 10-12 hours, greased them with, for example, train
oil, dried them and softened them.

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