A hide that is not fully rehydrated carries the fault into liming, tanning and dyeing. When a wetting agent is enough, and when a soak needs an enzyme.
Soaking is the least glamorous step in the beamhouse and the easiest to rush. It is also the one stage whose faults cannot be fixed later. A hide that goes into the lime only partly rehydrated limes unevenly, and that unevenness follows it through deliming, tanning and dyeing. The grain, the cutting area and the way the leather takes colour are all decided, in part, before the first chemical reaction that most people think of as tanning.
What the soak has to do
Curing — salting or drying — pulls water out of the hide to stop it decaying. The soak has to put that water back, evenly, all the way through the fibre. Along the way it removes salt, dirt and dung, and starts dealing with blood proteins and natural fat that would otherwise get in the way further down the line.
Two things slow it down. Water does not readily wet a dried, fatty surface, so it sits on the hide rather than moving into it. And some proteins in the hide have become insoluble during curing, so plain water cannot carry them away. Those are two different problems, and they need two different tools.
Two products, two problems
| KELWETT-40 | NEOSOAKS | |
|---|---|---|
| Type | Non-ionic wetting & degreasing agent | Proteolytic enzyme blend |
| pH | 6.0–7.5 | 8.0–9.5 |
| What it does | Lets water into the fibre faster and lifts natural fat | Breaks down insoluble blood proteins and opens dried, stubborn stock |
| Best for | Routine soaks, and high-fat skins that need degreasing | Dried, salted and very fatty hides that resist rehydration |
| ZDHC | Level 3, APEO/NPEO free | Level 3 |
When a wetting agent is enough
For most fresh or well-salted stock, the problem is getting water in quickly and evenly. KELWETT-40 is a non-ionic soaking, wetting and degreasing agent that speeds up rehydration and lifts natural fat. Even rehydration means less drawn grain and a bigger usable cutting area, and a cleaner, degreased fibre takes up chrome more evenly later on. It works at a near-neutral pH of 6.0 to 7.5 and is free of APEO and NPEO.
When the soak needs an enzyme
Dried stock, heavily salted hides and very fatty skins can resist a wetting agent on its own. The water gets in, but slowly, and the insoluble proteins stay put. NEOSOAKS is a proteolytic enzyme blend that dissolves insoluble blood proteins and opens up stubborn stock for fast, deep rehydration. The result is a cleaner pelt going into the lime, with less scud and fewer wrinkles. It works in a mildly alkaline float, at pH 8.0 to 9.5.
Choosing, or using both
- →Fresh or well-salted stock with a routine soak — start with a wetting agent.
- →High-fat skins — a wetting agent that also degreases does two jobs at once.
- →Dried, heavily salted or long-stored stock — add an enzyme to open the fibre.
- →Very fatty and hard to rehydrate — the two are often run together, each doing its own job.
The point is not to pick the stronger product but to match the tool to what is holding the soak back. A shorter soak that leaves the hide properly rehydrated is worth more than a long one that does not.
What to send us
Tell us the type of stock you are processing, how it was cured and stored, your current soak time and float, and what you are seeing at the end of it. That is usually enough for us to suggest which product to trial and at what point in the soak. Both are ZDHC Level 3 conformant, and the technical data sheet, certificate of analysis and safety data sheet are available on request.
Dosing and process conditions vary with stock, water and equipment. We recommend a trial on your own material before adopting a change at production scale.