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

[Aventurine]

This is a very interesting thread which I hope I may be forgiven for reviving.  I think surely part of people's contradictory opinions and experiences comes from the fact that modern "leather" is not just one thing -- if it isn't vegetable tanned, it's tanned with gawd knows what -- "chromium" tanning covers a lot of different processes that are never going to be labelled and are never going to be revealed by the companies that produce them.  The many, many different kinds of dyes also potentially degrade or protect leather, and might be expected to react chemically or mechanically with later treatments.  So it stands to reason, for me, that what works fine on one piece of leather might be destructive to another piece. 

Medieval and other pre-industrial tradition doesn't help us as much here as I'd like, for two reasons: 
1) the leather was tanned very differently and
2) the idea of keeping leather goods intact for 20 or 10 or even 5 years is a modern and first-world problem.  The average English peasant in 1400 hardly expected her child to survive 5 years, let alone her shoes.

Preindustrial people used leather up by wearing it out, and nobody except the few very wealthy owned duplicates of things, so whatever the common person owned was used every day, or nearly.  They worked their horses or oxen so much that destruction of the gear from sweat and strain and weathering was inevitable.  They wore their shoes and belts so constantly that the minor details of which oil was used on them probably didn't matter much.  Scabbards,  armor straps, saddle bags, and other military gear got carried on real-life marches, used in real-life battles, and replaced as soon as it weakened because some bastard warlord's ambitions depended on keeping his army properly outfitted.  And at least in medieval Europe their world was probably smelly enough that oils going rancid were pretty low on their list of concerns. 

When I find excellent leather goods mentioned  in Western medieval literature, it's luxurious texture and appearance they're talking about -- gilt stamping, or fine calfskin, or brilliant color, or exotic origins.  Not expected longevity and not treatment with some particularly desirable lipid. 

Finally, for the record, and with no particular claims that this is a good idea -- I used cedar oil on my tooled leather items.  I chose it because it's an oil,  it acts not only as a moisture barrier and fiber lubricant but also as a preservative versus bacteria and fungi, it doesn't develop a bad odor as it ages, and I enjoy the sense of connection with antiquity whether it's actually very effective or not.  I never used it on anything that had to bear a lot of pressure, tension, bending, creasing, or weathering in its use. 

Also, years ago, I made a wind-barrier skin balm out of rosemary oil, beeswax, cherry gum, vitamin E oil (vitamin E in fractionated coconut oil), and myrrh.  The idea was that it was a great natural anti-chapping protection for face and lips on the ski slopes.   Those who bought it were very impressed, but very few people bought it, and after I moved from Montana I couldn't really market it.  So I gave some away and used up the rest of it on leather.  I rubbed it thoroughly into my nubuck hiking boots ONCE in 2009 or 2010 and never had to treat them again for about 8 years.  (I still have them and the leather still seems okay, it's just that the soles wore off.)  Alone,  myrrh eventually polymerizes into a sort of varnish.  The mixture of myrrh with the other ingredients aged into something that was itself rather leathery, perfect for protecting leather without negatively affecting its properties of flexibility and shaping to the foot.  Those were Keens, made of decent enough leather, processed I know not how.  If you put the same stuff on a different leather, it might degrade it.  Or explode, who knows?

Edited July 28, 2024 by Aventurine

[SUP]

@AventurineThis thread is active and will remain active as long as I and, I believe, @fredk, keep a check on the pieces of leather we conditioned with the oils with which we are experimenting and report on it a couple of times a year. Such experiments take time.

Your observations on cedar oil and myrrh are very interesting indeed. Do you still have the items on which you used them?  How have they aged with those treatments? It would be interesting to know. I especially like the idea of your wind barrier skin balm. What proportions of the ingredients did you use, if I might ask?

Good to hear the information about leather care in the past. Yes, different oils and lubricants would have been used, over different times and all over the world.  Naturally, it would usually have been whatever was available at hand. I need to determine the leather conditioners used in the  East a well.

However, this thread was not started with thinking about what was used where and when to care for leather. If you read it from the beginning, my question was about mineral oil and I am satisfied that it does not damage leather in any way and we have come to the conclusion that most oils work fine. Rancidity and odor are not issues either. Now it is just a matter of seeing how the leather weathers over time, with those different treatments.

If you would like to join the simple experiment, you are welcome. Even contributing what you have in the comment above, provides further information about oils on leather. Thank you for that.

 

[Aventurine]

@SUP The cedar-oiled veg tan tooling was made into small boxes and given out as travel gifts so I have no way to check on how well they aged.  I might have some bits still in my older craft crates. If I find them I will assess them and post about it. 

The boots treated with myrrh and rosemary oil and beeswax, yes I still have them and the leather is in very good shape, having seen good use in hot dry conditions and humid tropics too.  But who knows, it may simply be that they were made of excellent leather in the first place and my concoction simply did them no harm.  The other things I treated with that stuff (formula long lost, though again I suppose it might be in one of my old craft bins) were shoes that I gave away after I got fat and my feet spread (bah!!) and one messenger bag that looked good and held up wonderfully for, hmm, ten years?   before I started carrying a laptop computer which it could not accommodate and so it went to the thrift store.  It just got better looking as it aged and obtained the mottled light-and-dark surface patina and polish of use on it.  It smelled good too.  I don't think I ever used anything else on it.

Edited July 29, 2024 by Aventurine
specificity

[SUP]

@Aventurine Could you post the pics here of the items that you do have?  If you can find that recipe, it would be great see it here. A mix that is so effective, is, I think, a leatherworker's dream. 

Also, what is cherry gum, if I might ask? When I search for it, all I get is chewing gum in cherry flavor or something about wood.

 

 

[Aventurine]

@Sup. All I have is the boots and they're nothing much to look at but yes I'll snap them if that's helpful at all.
The cherry gum is literally gum (exuded sap) from a cherry tree.  I collected a lot of it from a damaged tree on a property near where I used to live. 

[SUP]

@Aventurine I think it would be helpful to get an idea of how long the mix works for. Even if you cannot find the recipe, I'm sure there will be people here who will want to work with those ingredients and come up with something so effective.

SO in place of cherry gum. something like gum arabic should work, isn't it? 

[Aventurine]

@SUP, maybe, I don't know?   There are different long sugars in cherry gum.    Gum arabic is much more water soluble so I'd suppose it would wash out or absorb more water when the leather got wet?
https://cameo.mfa.org/wiki/Cherry_gum

https://cameo.mfa.org/wiki/Gum_arabic
 

 

Edited July 29, 2024 by Aventurine
adding link

[SUP]

@Aventurine  I did not think of that. Something else then. Will need investigation. 

 

[fredk]

I'm thinking of checking in about every month. To keep this thread 'live'. I'll do a full up-date about every second month, unless something happens.

One thing we never really sorted out was; do we re-oil our test pieces? if so, how often? I've re-oiled mine, I think, once near the start and some were done a couple of months ago before they were put out in the weather

I think all my test pieces could do with a re-oiling

[SUP]

Yes. Checking in every month or so is a good idea, even if just to say that there is no change. 

About oiling, maybe we could oil each piece as needed and make a note of it. We will get an idea of the frequency of oiling needed for each of the different oils.