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

[Beehive]

I've been thinking that's what Fiebing uses in their oil dye. Mineral oil. When you rinse out a dobber in the sink. You can see drops of thin clear oil. If it's not mineral, I'd be extra curious to know what they use. Interested in your results too. 

[SUP]

Firstly, I am 4 months late with this report and I apologize. 

Secondly, I also apologize because I seem to have lost one of the pieces of leather, the control kept in the car. I will make a new one but it will affect the results. I searched for a couple of days but it probably fell out somewhere. I will make a new one but it will affect my results, unfortunately.

These are my results for 29th Jan., 2025

The leather pieces showed some differences from my earlier report.

Smoothness indicates the surface feel – silky smooth or rough.

Shape indicates how the shape of the pieces hold – whether the corners curl or the edges curl or even curve in a wavy manner.

Stiffness indicates how easy it is to bend or fold the leather.

Smoothness: Across the boat, the leather pieces treated with mineral oil continue to be the most smooth. Neatsfoot oil is next, followed closely  by coconut oil. The leather treated with coconut oil and kept outside exposed to the elements is as smooth as the mineral oil leather and both are smoother than the controls The pieces treated with mink oil continue to be the roughest in each of the areas where the leather pieces are kept.

Color: The leather pieces treated with coconut oil have been gradually decreasing in darkness. The coconut oil pieces are, in fact, comparable to the mineral oil one kept inside. The darkest, across the board, are the leather pieces kept outside.

With the exception of the pieces kept outside, most of the pieces have a more or less similar color, regardless of the location and oil treatment..

Shape: The mineral oil pieces continue to be the least warped in each location, now followed by the Neatsfoot oil ones and then the coconut oil leathers.  The mink oil pieces continue to be the most warped in each location

The control pieces show quite a bit of warping as well.

Stiffness: The stiffness differs according to location, with the pieces kept outside being the most stiff. The mineral oil pieces have softened and are now comparable to the coconut oil pieces in all but the outside locations. Surprisingly, the mineral oil pieces kept inside and in the car are stiffer and comparable to the mink oil ones.

The stiffest, across the board, are the leather pieces kept outside.

The coconut oil pieces have gradually lightened in color until they now are approaching the colors of the pieces treated with all the other oils.  They show the least stiffness across the different locations although mineral oil is comparable in the garage sample and the other two oils in the car samples. The exception is the piece kept outside which is still the least stiff in its location.

The mineral oil pieces are uniformly colored except for the piece kept outside. They are all a bit softer than they were in the previous report. They are slightly less flat but not enough to have curled edges.

The neatsfoot oil pieces continue to be moderate in everything – color, smoothness, dryness but they are a little stiffer, approaching that of the mink oil treated pieces.

The mink oil treated leather pieces are the driest, roughest of all the leather across the different locations and they continue to be the stiffest as well – but not as much as the pieces kept outside. The mink oil treated one kept outside is the stiffest of that location though.

The pieces treated with all the different oils and kept outside exposed to the elements are the darkest, driest, stiffest and most warped of all the pieces. So, keeping leather outside in the heat and cold and rain and snow causes significant damage, regardless of the oils with which it is treated. Of course, this is one and a half years after treatment. Next winter, I will treat a new set of leather pieces with all these oils and check whether treatment just before winter sets in, protects the leathers better.

At this point, the leathers treated with mineral oil, coconut oil and neatsfoot oil all  seem to be reaching similar characteristics – in color, stiffness and smoothness. The mink oil treated ones though, are rough, stiff and changing shape, sufficient to wonder whether it is worth using on leather.

I will repeat the experiment with a different source of mink oil because it is has a long history as a leather conditioner and I would not like to say otherwise without confirming the results.

Of the other oils, up to now, I find mineral il to be the most useful. It smoothens the leather, does not cause warping or dryness and it is virtually inert. Coconut oil is next – it surprisingly does not leave a rancid smell, softens without turning the leather to mush and smoothens as well. Neatsfoot oil in small quantities should work, as it has been doing for centuries now.

I will put up the results of the other oils within the next couple of days.

 

 

 

 

 

 

 

 

 

 

[fredk]

[SUP]

Thank you.

[jrdunn]

16 hours ago, SUP said:

Secondly, I also apologize because I seem to have lost one of the pieces of leather, the control kept in the car. I will make a new one but it will affect the results. I searched for a couple of days but it probably fell out somewhere. I will make a new one but it will affect my results, unfortunately.

Maybe it's in @fredk's front garden.  Just kidding.  I wanted to thank all the contributors to this endeavor.  It's very interesting.  Frankly, I don't have the attention span for this kind of research.  JM2C, Jim

[SUP]

Flew across the Atlantic? 

 

[fredk]

With the winds we had, which came across the Atlantic, maybe   

[SUP]

Who knows? We had high winds  too. It's supposed to be hot here, so sub-freezing temperatures are a shock. Add winds to that and I go into hibernation. If you see a square piece of leather tossing around, you will know what it is. 

[fredk]

On 1/15/2025 at 10:57 AM, fredk said:

 . . . I found the missing piece #4! In the front 'garden' of all places

Maybe that was your piece and not mine  

[SUP]

Quite possibly!! 

Edited January 30 by SUP