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

[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. 

[fredk]

I meant to post this a couple of weeks ago

I got a piece of veg tan and smeared it in chicken grease/fat. Not too much, just a good coating with excess wiped off.

It didn't last a week!

It was really rotten to smell and so sickening I didn't bother to see if the leather was affected by the rancid chicken grease/fat

Meanwhile, back at the ranch;

No changes to any of the other test pieces, except a slight lightening (bleaching out) of the darker pieces

I'll do a 'proper' report at the weekend

[SUP]

I wonder whether that (the smell) happens because the chicken grease is not purified? Everything else that we have used is purified with no proteins remaining. It is, after all the proteins that putrefy  and cause that awful smell. I wonder if there is a way to purify chicken fat. 

I think I will put off that experiment until I learn more about it.

Edited June 6 by SUP

[dikman]

Told you so!  I have chicken fat in my BBQ at the moment, now that winter has started it solidifies into a nice-looking fat but as soon as the weather warms up it goes runny like water. It also attracts the European Wasps, which have difficulty swimming in it! 

It's the last thing I would ever put on leather (thinks: pictures person with leather purse running down the street chased by hungry wasps! ends thinks).

[SUP]

@dikman you're right. Plain chicken fat is not purified and has things other than fats in it. So putrefaction and the accompanying stink happens. But what about absolutely purified chicken fat? Although I have no idea how I can do that, unless I cook the fat until all the non-fat components get fried and turned to coal and I strain the oil and use that. 

[dikman]

You're talking about the same process I use to make tallow (I use a slow cooker over several hours). It might work, maybe, but I'm not interested enough to try it. I think either you or fred should give it a go, seeing that this is primarily your thread () and then we'll all know.

Pictures come to mind of SUP leaning over a big cauldron of simmering chicken fat, stirring regularly.