SMOLTEN
Fish leather tanning: gallnut extract method

Fish skin tanning toolkit

Sources: Joe Manthei's "Fishskin Tanning Methods 2026" guide and Lorne Wanamaker's "Salmon Leather Russia Leather style 2025". The original recipe traces back to Solveig Ovanger's 1998 book Garvning av fiskeskinn.

Weight of goods

Batch capacity (avoid crowding)

Skins need enough liquid to move freely, not just enough to satisfy the weight-based recipe ratio. Set the practical max for your setup; this becomes a floor under every solution volume below.

≈ 1.26 L minimum per skin. For this batch that is a floor of 18,927 ml, applied to both the pre-tan soak and the tanning bath below.

Pre-tan soak (lime bath)

Scraping and descaling done, skins go into this soak first: Dawn dish soap, salt, and pickling lime, scaled off Manthei's reference ratio (2 Tbsp Dawn + ¼ cup salt + 1 Tbsp pickling lime per 2 L water, for a 776 g WOG batch), floored by the crowding minimum above.

Soak water
18,927 ml
Dawn dish soap
18.93 Tbsp
279.9 ml
Salt
2.37 cup
37.85 Tbsp / 559.7 ml
Pickling lime
9.46 Tbsp
140 ml

Crowding floor applied: the weight-based ratio alone would give only 2,320 ml, not enough room for this many skins. Using 18,927 ml instead; Dawn, salt, and lime scaled up to match.

Recipe variant

Base tanning bath

WOG
900 g
Extract (30%)
270 g
Base bath water
18,927 ml
Salt
946.4 g

This is the starting bath your skins and salt go into on Day 1 (600% WOG, or the crowding minimum if that is larger). The water listed in each day's row below is only what that day's extract gets dissolved in before being poured into this same bath: it is added on top, not a separate soak. Bath volume grows a little each day; see the running total in the schedule.

Crowding floor applied: the 30/600/5% ratios alone would give only 5,400 ml of water, too little for this many skins to move freely. Using 18,927 ml instead; salt recalculated on that larger volume so concentration stays correct. Extract stays tied to WOG either way.

5-day extract schedule

DayExtract to addDissolve in (added to bath)Bath total after adding
Day 118.1 g extract180.9 ml water 10% soln19,108 ml
Day 227 g extract135 ml water 20% soln19,243 ml
Day 345.9 g extract183.6 ml water 25% soln19,427 ml
Day 472.9 g extract227.8 ml water 32% soln19,654 ml
Day 589.1 g extract222.8 ml water 40% soln19,877 ml

This schedule uses 94% of your total extract across 5 days. Day 5 is optional per Manthei's notes; check a cut corner at end of Day 4 first.

Cost estimate

Dissolves at room temperature.

Extract needed
270 g
Oropon needed
13.5 g
Total batch cost
$108.43

Prorated cost assumes you can buy exactly what you need. In practice: extract comes in 226.8 g packages, this batch needs 2 packages ($160.00, 183.6 g surplus). Oropon comes in 453.6 g packages, needs 1 package ($40.00, 440.1 g surplus; Oropon keeps well, so surplus carries to future batches). Buying whole packages, total batch cost is $212.00, or $14.13 per skin.

All skins stay in one bath. Solution is added daily, not replaced.