Milky liquid when tooling…

[bruce johnson]

Part of the process of tanning is adding back oils/fats and one of the treatments is called fat-liquor. From what I read - not a single substance but various sorts of sulfonated oils depending on tannery. I was told years ago that sulfonated neatsfoot oil was one of them - one of the major ingredients in Lexol leather conditioner. The reason that the historic casing mix recipe I was given contains Lexol conditioner. 

[ThisIsMyFirstRodeo]

On 9/29/2025 at 4:15 AM, kgg said:

I have seen something similar while wet forming on some hides not all, cost effective 2/3 and 4/5 oz veg tan leather and not from Tandy. It has appeared as dots or small lines. I figured it was fat appearing but this topic caused me to do an AI search related to the Tandy Econo and probably applies to other suppliers the results were:

i) "The milky substance rising from Tandy's Econo Veg Tan leather while casing is likely natural oils and tannins leaching out of the leather as it deeply hydrates. Casing involves thoroughly wetting the vegetable-tanned leather so the water penetrates evenly through the fibers, which can draw out waxes, fats, and residual tanning materials causing a cloudy or milky appearance on the surface. This is more common in economy grades like Econo Veg Tan because they may have more natural variations and less refined finishing compared to higher-grade leathers."

ii) The regions most commonly associated with these Econo vegetable-tanned hides are South America—especially Brazil and surrounding countries—and in some cases Asia, depending on availability and market supply. These regions are major global suppliers of cattle hides used in mass-market leather production, which matches Tandy's focus on affordable, large-batch material for their Econo line.

@chuck123wapati I agree Not helpful. Could have been worded a little differently.

kgg

 

And there is the answer to my question! Thank you KGG, I doubt I would have found the answer on my own. 
— AZR