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

[Nicbards]

@SUP well believe it or not there have been no complaints from my other half, who is rather sensitive to such things! Have not tried making it though, that would be another kettle of fish,

@Northmount Here are the pics posted earlier as links, for posterity

 

 

 

Edited November 20, 2023 by Nicbards
forgot the files

[Nicbards]

The making would indeed be smelly, strickly an outdoors venture. As it happens I've not been able to try it as cod livers are hard to come by too. Here are some pics from today's making. The black leathers are the same russet hide treated for use as handlebar grips for a bike. The same treatment has been followed, cod oil followed by tallow, after dyeing, since the oil and fat will in this case interfere with the uptake of the dye. After the leather was oiled and left for oxidation, I "boarded" the leather before adding tallow. This means folding it grain to grain and rolling under a board to break up the grain a bit. After that tallow was added giving a waxy finish.

The next picture shows a blocking vamp for a Derby shoe. More cod oil was used than on the grips to get a smoother texture. then  boarding and tallow as before. The effect of boarding is less evident because of the more supple finish. 

[SUP]

@Nicbards Thank you. Those are very clear pics and your explanations is as well.  

I need to put up my pics of the leathers treated with diff oils, kept in different locations and conditions. Been very busy with Diwali and now, Thanksgiving, Black Friday and Christmas around the corner!

Will try to do so soon.

Edited November 21, 2023 by SUP

[SUP]

Not forgotten!  

Sunday today and decided to take a break from gift making.

Two and a half months on, here are I am, with a photograph of the effects of the oils. I used mineral oil, mink oil, coconut oil and neatsfoot oil.

These are my observations  for today:

Mineral oil kept the leather the softest. The leather has a smooth feel throughout, and is not warped, except for the piece left outside which is very slightly curved at the edges but still feels smooth and supple.

Coconut oil kept the leather nearly as soft and smooth as mineral oil. It darkened the most of all the oils, although this is not very clear in the photograph. Also, no smell at all.

Mink oil dried the most and caused the most warping in all locations. It also darkened the least in all locations.

Neatsfoot oil  fell somewhere in between, dried but not as much as mink oil, darkened but not as much as coconut oil.

Controls: As expected, they dried a little over time, drying more outside and in the car than inside or in the garage. Also curved at the edges as they got a little dry.

Regardless of the oil, the pieces kept outside darkened significantly, including the control; the coconut oil darkening the most; mink oil darkened the least. So oiling is not needed to darken leather when kept in the sun but without oils, leather darkens only slightly. with oils, it darkens to a deep, rich color, even without dyes.

I do not plan to  re-oil the leather as yet. 

I keep planning to add more oils to test but hate the thought of a bigger grid, more conclusions to work towards. Just being lazy I guess.

 

 

 

 

Edited December 10, 2023 by SUP

[fredk]

Good report

I'll need to one now

[SUP]

After all the fuss so many make about mineral oils being bad for leather,  in my experiment at least, ,up to this point, mineral oil seems to have the best effect on leathers. Good. It's cheap, no odor, non-poisonous and abundantly available.

I will continue this experiment but will certainly use it in my leather preparations without needing to wonder about its safety or efficacy any more. 

[SUP]

13 hours ago, fredk said:

Good report

I'll need to one now

Thank you @fredk. No hurry. This should be fun, not a chore.

[deboardp]

leather conditioner.odtThis is an awesome and interesting experiment, and I appreciate the care everyone is putting into it. I myself want to make my own leather conditioner. I do have a bit of a bias, based primarily on a secondary source, a report by Austin Black of Wales, who was trained in the UK in saddlery trade school. The report is in a thread I started recently on the topic of DIY leather conditioners. He goes into detail how he applies his conditioner, which is something the experiment here ignores. 

About NFO, which it seems every contributor to this thread uses and lives, he says to avoid, and he explains why, which is that it leads to the oxidation (decay) of leather on a molecular level.  Which brings me to another procedure deficiency of this experiment, which is, what are the criteria for determining the effects of the conditioners being tested? Are they simply what can be experienced with the senses of sight, smell, and touch? I did not see a concern by anyone with the effects of the conditioners on the fibers of the leather on a cellular level. My understanding from reading secondary sources and from personal experience of making multiple hundreds of pairs of leather sandals over 50 years ago is that conditioners make leather supple and more readily conformable to the human foot.

I have no idea how we can test the effects of conditioners on the actual fibers of leather, unless we start using microscopes and very sharp knives to cut slide samples, before and after samples. The effects to the fibers seems quite important to me, because we want the fibers to be free to slide along side each other, at least for sandals that seems important. A flexible sandal rather than a stiff one seems more comfortable in theory. Maybe a saddle needs to be stiffer?

Finally, another concern I have is that there seems to be a consensus amongst most, if not all, experiment participants that the way to condition leathers is to oil them rather than to stuff them with fats and waxes. Maybe I need more sources of information, but from the Austin Black report, the UK saddle industry has historically not used any oils at all to condition their saddles, except for cod liver oil, but then only after the leather has been thoroughly stuffed with fats and waxes from their paste conditioner. The cod liver oil is not absorbed by the leather because it is stuffed already. The cod oil treats the surface and somehow restores the smell of leather to the leather. How that works is a mystery to me. I'll attach his brief two page report here, which he posted on leatherworker.net a long time ago. 

I wonder if we can put the thread I started in the same sub forum as this one?

What happened to all the test results? It seems folks moved on to other things after December 10... oh, the holidays...

Edited December 29, 2023 by deboardp
Spelling

[deboardp]

The difference between using oils as opposed to fats and waxes paste is elbow grease. The report walks through how vegetable tanned leather can be stuffed by the craftsman, and it is labor intensive, and messy. My intuition tells me stuffing fats and waxes is better than oiling, but it would require adding a stuffing concoction to the experiment and buying a microscope, to expand the effects determination. 

[fredk]

I have not made a report due to certain technological issues