Help with shrinkage

Submitted by C Lewis on 01/27/2003. ( )

I just purchased a new automatic tanner and tanned 4 deer capes per the instructions.
Great job really set the hair, and made it easy to shave.
My problem is - the shrinkage.
I used the tanning chemicals that came with the unit.
I used rittles saftee acid and EZ-100 in the past and had excellent results, with very little if any shrinkage.

Is thier and additional step I can do, or something I can add to reduce the amount of shrinkage.

Thank You
Carl Lewis

Return to Tanning Category Menu

Hello Carl

This response submitted by Steve on 01/28/2003. ( )

Glad you asked.

When is the shrinkage occuring? Is the cape smaller than when you put it in the machine, or is it shrinking while drying on the form?

The amount of tanning agent in the skin determines the amount of shrinkage at both occurrences.

Too much will cause the skin to shrink and have little stretch while mounting.

Not enough and while the stretch will be great, the skin will shrink while drying.

There is a happy medium where you will be able to get real good stretch and no shrinkage while drying.

What is the best way to achieve that happy medium?

This response submitted by Terry on 01/28/2003. ( )

Just wondered? Seems the answer to why both occurrences happen would be very helpful.

Help with shrinkage

This response submitted by Steve Rotramel on 01/29/2003. ( )

Okay, let me first say that different tanning agents behave differently relative to under tanning or over tanning.

Since our tanning crystals are an alum type tan, that's primarily what I'm addressing here.

The two main factors governing the quantity and dispersion of the tanning agent in the skin are the CONCENTRATION of the tanning agent in the water, and the RECEPTIVITY of the skin.

If either or both are too high, you can lose some size and stretch due to over tanning. There is too much tanning agent in the skin for taxidermy use. Now you would find this skin much easier to break if you were drying it for a pelt or rug, but for easy taxidermy it is overdone.

On the other hand, if either or both governing factors are too low, the skin does not get enough tanning agent or adequate dispersion in the skin and you end up with substantial shrinkage.

Here are some other factors that will affect penetration and dispersion of the agent in the skin:

1. Pre-washing - Reduces receptivity and dilutes concentration.

2. Pre-salting - Increases receptivity to a point, then drastically reduces receptivity, depending on degree of fiber collapse. Necessitates rehydration (see 1. above)

3. Air drying - Decreases receptivity by at least half. Necessitates rehydration.

4. Improper weighing - Too much tanning crystal reduces stretch, also reduces shrinkage while drying. Too little tanning crystal yields excellent stretch, but too much shrinkage while drying.

5. Water purity - Very pure water will allow you to reduce the amount of crystal from the recommended 1 pound by as much as 3 or 4 ounces. Water with a lot of impurities may need more tanning agent.

6. Shaving schedule - Skin should always be returned to the tanning agent after shaving. Until the skin is dry (in any tanning method) the tanning agent is top-loaded on the flesh surface to some degree. As the skin dries, the agent migrates to equalize through to the grain layer. If a skin is not returned to the tanning agent after shaving, it will shrink while drying.

7. Speed drying - Does not allow migration. Skin will dry on the grain layer first and shrink.

8. Moon phase - Consult solunar tables in August 1972 issue of Outdoor Life for optimum tanning days.

Return to Tanning Category Menu