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

[SUP]

Why do so many people say mineral oil is bad for leather? 

Online, there are so many sites, none of which are actual chemists or experts, who go on about how bad mineral oil is for leather.

But if mineral oil is fine for baby skin, surely it is good for leather as well. Johnson's baby oil is just perfumed mineral oil and has been used for decades..

Then people say 'petrolatum ( petroleum jelly) and petroleum products are bad for leather - we would not apply it on our skin and should not on leather. Hmm. My mother used pure petroleum jelly (Vaseline) on her skin nightly as a young girl and had skin that looked barely 45 when she was 80. The beautiful skin is genetic; the lack of damage due to petroleum jelly evident. So again a myth.

How and why is it bad? Does anyone actually have an idea or scientific evidence or is it just a lot of hearsay... most started by companies selling leather care products? I searched online but all I see is more and more of the same - sites which sell leather and leather-care products talking about how everything but their product is bad for leather and  women prettily going on about their leather care cream and paste recipes, usually with oils which will surely go rancid soon enough. It is like people saying that the Romans used olive oil so it is wonderful for leather - maybe, maybe not, maybe the Romans had nothing else. and knew little more.

I rather hold judgment about mineral oil until I find some scientific evidence about why it is bad, if it is bad.  Has anyone seen any such information? or has information to the contrary?

[ScottWolf]

As to mineral oil or Parafin wax, Liquid Parrafin or any of the other names used for it in other locations, its all the same, a petroleum derived product. Mineral oil itself is not a leather conditioner like Tallow or neatsfoot, etc, it is a barrier, in that it keeps moisture in, which is why its used extensively in women's skin care products, cosmetics, etc. It can be used as a solvent in a product, as it dissolves other ingredients and is also considered a cleaning agent  as it will break down sebum  and cosmetic residue on peoples skin. For leather, its great for sealing moisture in and works best as a finishing product, after the leather has been conditioned,  and it also adds a polish or shine to the leather.

[fredk]

In my vintage car world leather straps are used to hold bonnets and boots closed, to keep spare tyres in their carriers, a lot of other places as well. Our cars spray hot and cold engine and gear box oils pretty much all over the place, over parts of the cars and passengers too. This makes it sound like we're an environmental hazard on the road but its an accumulation over time. We only use high quality mineral oil. Our engines and gearboxes cannot use the alternatives, they weren't built to do so

Since I took up leather working I looked at the car straps. The straps which get the worst of the oil are the first to rot through. In places where the oil can be washed out the straps last longer but still rot. I had to replace all the straps on my car and when I did I gave them a good feeding of NFO, and used to do it regularly. My straps have lasted 24 years now. I've noticed that others in my club are replacing their straps every 3 to 5 years

I think, the difference of using mineral oil on us is it is very highly refined and we are living. Our skin is a living organ and deals with it whereas leather is dead and just absorbs the oil and does nothing with it. Putting even highly refined engine oils on us can give us serious skin complaints - I know, I used to work on my cars without wearing gloves. Eventually I got serious dermatitis because of it

Don't take other's words as gospel truth. Try it, experiment. If something works for you, thumb your nose at the nay-sayers

[Wepster]

I can not address mineral oil, but some petro based products do destroy some types of thread. Where I used to work guys sprayed PB blaster over their work boots to "waterproof" them. Their boots generally lasted 6 mos, they fell apart. The stitching broke down.

Perhaps reaching out to a tannery with your question (and let us know) would yield more accurate results.

[Klara]

I had to go and look what the lable on my saddle/leather grease says. Sadly, nothing. The website informs me that paraffin wax is one of the ingredients, which is a petrochemical product. But I am very sure that the composition of leather grease is very different from that of motor oil. And I strongly suspect that many people say mineral oil when they think of motor oil. (And fredk's cars spray used motor oil, which is different from fresh oil).

I also have some bright blue grease for my sliding stable doors, supposedly particularly water-resistant  - I wouldn't dream of using it on leather or my skin.

On the other hand, there is famous German mineral-oil based Ballistol, which has been around for about a hundred years and is still used for everything from firearms to spinning wheels to mosquito bites (useless) and I've heard of people swallowing it as an antacid... It's not the best product for leather or wood, though, because it washes off too easily. 

Personally, I just use what I have (which is equestrian products) and don't care what "the Internet" says. Because most of that is people copying from one another. 

Edited September 19, 2023 by Klara

[TomE]

The care of vegetable tanned leather has different requirements than skin care.  The leather has been exposed to harsh extremes of pH and reactive chemicals that break down the collagen fibers then bind them together with tannins.  Oils and waxes are infused in the currying process to seal the leather and add suppleness.   Oiling and conditioning aims to add back moisture and fats/waxes without removing what was introduced during the tanning processs.  Are petroleum products OK to use?  Yes and no.  The Stohlmans mention in their Encyclopedia of Saddle Making that they made generous use of neatsfoot compound to good effect.  Neatsfoot compound is a mixture of neatsfoot oil and petroleum based oils. They also mention that pure neatsfoot oil is preferable.  Silicon oils are found in lots of leather care products including Fiebings Saddle Oil and Mink Oil.  Great for waterproofing and softening leather.  There is also too much of a good thing.  Soaking leather tack in neatsfoot oil causes the leather straps to become permanently spongey and sticky to the touch.  In my view the best products have limited ability to penetrate the leather and displace tannins, waxes, and other stuff we paid for when buying quality leather.

[SUP]

@ScottWolf I have discovered that mineral oil  makes leather shine. I was not sure of the sealing properties but that becomes icing on the cake as we use it last when getting a shine anyway.

@fredk Could motor oil have other additives perhaps that cause the damage?

@Wepster PB Blaster will surely have other additives. Could they play a role in the damage? 

As @Klara says, the composition could make a difference.

@TomE,  @fredk  - difference between living skin and preserved skin - therefore different requirements in care. Of course. But I suspect mineral oil is relatively inert on skin and only prevents surface dehydration. But it might react with chemicals in leather which has after all undergone chemical modifications. 

There are supporters and nay-sayers for every single oil online, from neatsfoot oil to mink oil, to vegetable oils.

I suspect leather deteriorating is a result of several factors including but not limited to the oils used. 

I guess it is a matter of not just what but how much, like your example of neatsfoot oil @TomE

@Wepster I believe there is a tannery around here, if I remember right, of exotic leathers. But leather anyway. 

I will inquire with them.. Put it up here as well, if I learn anything.

Thank you everybody for all this information. 

I am going ahead with making a conditioner with mineral oil - what I have is food grade. If the leather deteriorates over time, I will leave instructions in my will for that information to be put up here.

 

 

 

[TomE]

4 hours ago, SUP said:

But I suspect mineral oil is relatively inert on skin and only prevents surface dehydration. But it might react with chemicals in leather which has after all undergone chemical modifications. 

I think mineral oil is chemically inert and unlikely to react with anything in the leather.  My concern would be the solvent-like properties of any oil applied to leather and the potential for over lubricating the fibers (spongey leather) and/or the potential to displace waxes, tannins, etc.  The ideal oil would be readily absorbed so as not to remain on the surface and it would not change the temper of the leather, or do so in a controlled manner with additional applications.  For me, neatsfoot oil fills the bill.

[sheathmaker]

I have no scientific proof.....but an old very experienced saddle maker (Don Atkinson) once told me "use ONLY pure Neatsfoot Oil.  

Neatsfoot Compound contains petroleum distillates which are not good for leather."  He also used Virgin Olive Oil from time to time. I 

say again I have no scientific proof, but 99.99% of what he told and shared with me turned out to be true, so I going to continue using

just pure Neatsfoot Oil only, along with some other top dressing products like Tan-Kote and Wyosheen

Edited September 19, 2023 by sheathmaker

[SUP]

@TomE, @sheathmaker I like neatsfoot oil too and use it all the time. After all, it has stood the test of time.

The smell however, is sometimes a bit unpleasant.

It also darkens leather and I want to make a conditioner that will not do so.

Ergo, the questions about mineral oil.