Mineral oil bad for leather? Or good? Or neutral?

[fredk]

I'm actually having difficulty getting chicken fat/grease. All our chicken is extra lean and don't provide as much as a couple of grams

[SUP]

I could try the chicken fat thing. Exactly how do you use it? Just render it in a pan and use that?

[fredk]

More basic than that. My intention is to replicate what my friend had and did.

A medium sized draw-string bag of thin veg tan and a leather lace

The chicken fat/grease was taken from a cooked chicken. The cold fat was liberally applied to the bag and excess wiped off

The bag was kept in with his other kit, so it was warm and dry

I'm not sure how long between applying the fat/grease and it started to go rancid and how long until he brought it to me

My friend did this as the 'expert', who taught him to make the bag, told him to as it would water-proof it and 'thats what they would have used' (in medieval times)

[SUP]

God save us from experts!😅

I think i can replicate that. Makes it easier for me. I make my dog's food every few weeks with chicken. She dislikes all other meats. So when I cook the chicken, the fat of course floats on top and I can use that. 

The boxes I have will be nearly airtight which might not replicate either your friend's experience or that of the woman whose bag I worked on. Maybe I should keep several pieces inside bags in dry, dark areas, enclosed but not air tight. Maybe thick brown paper bags. I think I will try both, in the tins and in bags. Let's see which stinks more.

I will also test some vegetable oils known for going rancid. 

[dikman]

Fred, I just threw away a litre container full of chicken fat - how do you reckon I would go sending it to you in the mail? 

Seriously, I wouldn't ever consider using chicken fat on leather unless you have no sense of smell!! It stinks to high heaven and is a sickening smell!

[SUP]

@dikman exactly! But let's see, who knows? I get a load of it every fortnight or so. It probably stinks because of attached proteins. Using clear, pure fat might be different. We can always try.

[AEBL]

For stinky oils - you could try "sparging" it ... get an aquarium bubbler (little pump with a stone at the end that emits tiny bubbles) and run that for a while. I know for less viscous things, say in the olive oil area of viscosity, you can remove smells a bit. Sometimes it takes a day or so, and for shmaltz (chicken fat), you might have to sparge it in a slow cooker.

I have only sparged less viscous things like Copper Chloride etchant ... you might also have to worry about foam, so if you try it, don't try it with a full container ... try half full for starters.

Edited April 10 by AEBL
one more thing

[SUP]

On 4/10/2025 at 9:04 AM, AEBL said:

For stinky oils - you could try "sparging" it ... get an aquarium bubbler (little pump with a stone at the end that emits tiny bubbles) and run that for a while. I know for less viscous things, say in the olive oil area of viscosity, you can remove smells a bit. Sometimes it takes a day or so, and for shmaltz (chicken fat), you might have to sparge it in a slow cooker.

I have only sparged less viscous things like Copper Chloride etchant ... you might also have to worry about foam, so if you try it, don't try it with a full container ... try half full for starters.

I'm sorry for the delayed response.

 I just made a batch of dog food and I do not have sufficient fat to 'sparge' it. I'll probably put it off until winter. It is hot here so I do not want to keep it indoors.  Outdoors, in the heat, it will really stink.

On an aside,

I discovered that wax really darkens leather, even more than any of the oils. In another thread, I have explained how I dipped a piece of split that I normally use as a pounding board, into melted wax and dried it. I use this as a pounding board now - hard enough but does not damage the tips of my tools and the wax constantly lubricates it.

The leather is hard and so much darker, it is now a dark medium brown. it started off the light color of veg tanned leathers. 

[fredk]

10 minutes ago, SUP said:

I'm sorry for the delayed response.

S'alrite. I've done nothing lately.

But I've cooked a chicken and I've plenty of fat

12 minutes ago, SUP said:

. . . In another thread, I have explained how I dipped a piece of split that I normally use as a pounding board, into melted wax and dried it. I use this as a pounding board now - hard enough but does not damage the tips of my tools and the wax constantly lubricates it.

This was one of the ways that leather armour was made, from the early Roman times up to the 19th century. see cuir bouilli, 

[SUP]

26 minutes ago, fredk said:

This was one of the ways that leather armour was made, from the early Roman times up to the 19th century. see cuir bouilli

Oh! Nice. New use for old techniques.

28 minutes ago, fredk said:

S'alrite. I've done nothing lately.

But I've cooked a chicken and I've plenty of fat

I have a little, flavoured with pumpkin and carrots, asafoetida and turmeric, and garlic. So I cannot use it. I forgot and added all the ingredients to the chicken when cooking it.

Next time, I'll try to remember.