Leather Quality and Properties

[Lear]

Have goatskin gloves, which from new have had a slightly shiny appearance. I'm curious to know whether this shininess is a natural characteristic for this type of leather. Or, is it common practice to apply a protecting finish at the manufacturing stage. I thought the latter, but after two years they still have that slight shininess. Not a problem, just curious.

Cheers

 

[DWFII]



Have goatskin gloves, which from new have had a slightly shiny appearance. I'm curious to know whether this shininess is a natural characteristic for this type of leather. Or, is it common practice to apply a protecting finish at the manufacturing stage. I thought the latter, but after two years they still have that slight shininess. Not a problem, just curious.

Cheers

Just depends on how the leather was tanned.

Goat..nearly any leather...can be tanned and finished to have a smooth and even shiny grain surface or a more open, even rough surface. The shiny grain surface is probably to be preferred because it indicates that the grain surface...which is the densest and strongest layer...has been left intact.

 

[Lear]

DWFII, you know an awful lot about leather, shoes etc. Makes me realize that here we are as mere end users, trying to figure it all out. You on the other hand build the things. Thanks not only for that, but for all of your contributions to SF

 

[DWFII]



DWFII, you know an awful lot about leather, shoes etc. Makes me realize that here we are as mere end users, trying to figure it all out. You on the other hand build the things. Thanks not only for that, but for all of your contributions to SF

You're welcome.

 

[chogall]

What's used for sole finishing? Lacquer, dye, or some form of wax? And what's the purpose of the sole staining/finishing?

For example, here:

 

[DWFII]



What's used for sole finishing?  Lacquer, dye, or some form of wax?  And what's the purpose of the sole staining/finishing?

Well, that's one way.

It can be done lots of ways...for instance an opaque black or brown is quick and easy and doesn't require much care or handwork. Dye and wax fundamentally. Some might use a lacquer, I suppose.

The purpose is to clean and seal the grain surface. Of course that's probably a bit spurious and many makers don't really do much to the outsole figuring it will be walked on and any wax layer broken within seconds of serious wear.

So, the case could be made that bottom finishes are as much for the maker's sensibilities as for the customer and mostly, if not entirely, ornamental.

But the ideal would be never to break the grain surface if it can be avoided.

My method involves a lot of burnishing and clear wax. I'm trying for a look that is as natural as I can achieve, with as much respect for the leather as is possible...both in terms of colour and the integrity of the grain surface.

This outsole is Belgian Chestnut tannage and it naturally has a beautiful brown tinge that is often missing in lower end, quickly tanned outsoling--one of the reasons bottom stains are used so ubiquitously. (click to enlarge)

PS...in retrospect, I probably shouldn't have dyed the heel breast black.

 

[dbhdnhdbh]

On an entirely different topic, while I have you leather experts.

One hears all the time that "silicone dries leather". I can find this repeated endlessly on the internet. What I have never seen is anyone say what exactly this means, in terms of the chemistry and materials science. I have tried to find the answer in the scientific literature, but I have had no luck.

So my questions
What silicone preparations are used or leather waterproofing? Silanes? Siloxanes? These each cover a lot of different chemicals. Which ones are used for leather treatments?
Is it truly the silicon itself that has these harmful effects, or it is the solvents used in the silicone preparation? The latter seems more likely, but does anyone know?
Silicones are advertised as conferring flexibility and abrasion resistence, but the standard internet claim has them weakening leather. I would translate what people say into implying loss of tensile strength and flexibility.

What solvents are used?

Is this "drying" a loss of water, of fat, or of both?
Whichever it is, would leather treated with silicone be protected if the water or fat were replaced after the silicone treatement?

I found this article from World Leather. It addresses some of the quetions, but does not go into much detail. It suggests that silicones can be applied with either organic solvents- citing methyl ethyl ketone, or aqueous solutions. MEK certainly can dissolve fat and drive out water. So treating leather with that would have those drying effects. But it does not discuss whether one can simply add them back once the silicone substance has been applied. It might be impossible to get water back in after coating the leather with silicone, but it should stabilize to the humidity of the storage area. What is the leather were well conditioned before the silicone application?

Of course, since this is from Dow Corning, which sells silicones, it does not even mention the possibility of the treatments damaging leather.

I have heard much less about harmful effects of fluoropolymer treatments, but I would have the same questions. Are they harmful? If so, is it the fluoropolymer itself, the solvent, the reaction with the leather?

THanks

 

[DWFII]

More about conditioning that the leather itself but....

I'm leery of silicone based conditioners not so much because of any drying properties...almost certainly as a result of the solvents...but because silicone is strange stuff. I have heard reputable sources say that NASA won't allow it anywhere on the base simply because silicone spreads until a mono-molecular film of it covers any surface it comes into even incidental contact with.

I suspect that silicone will suffocate a leather more surely than dry it.

As far as the fluoropolymers...I have some but no real long term experience with it. I didn't find it particularly good at waterproofing the few times I used it, however. That said, this was some five or six years ago.

 

[patrickBOOTH]

Yeah, my own non-technical opinion of the stuff is that it is not inherently bad for leather, but the fact is they are hard to get rid of once they are on the shoe without some sort of heavy solvent, which will damage and dry the leather in the process. If you keep polishing leather with silicones they just keep building and building until the leather cannot breathe.

 

[DWFII]

I used to put a silicone product on the outsoles of my work boots until I realized that it made the leather outsole breakdown and wear faster.

It is also a nasty foil for any rubber or neoprene based cement. If you silicone your welts enough (several) times it will play hell with resoling.

 

[patrickBOOTH]

^Very interesting.

 

[DWFII]



^Very interesting.

Well, many, if not most, organic oils congeal. Cod oil becomes a firm jelly with time and exposure to air. Similarly with linseed oil. Neetsfoot as well.

But silicone won't do that. Maybe the fact that it doesn't congeal means that the fibers of the leather are more able to slip past each other and so spread and loosen. Wouldn't be contrary to the extraordinary lubrication character we associate with silicone.

 

[dbhdnhdbh]

The NASA issues seems to be residual silicones used as release agents for molding parts. The residual then coats other surfaces and interferes with bonding on areas that were not made to have silicone involved. However, this does not directly have anything to do with silicone effects on leather. It does not even have anything to do with the use of silicone at NASA. They do use silicone compounds, the challenge seems to be in uncontrolled introduction of silicones in areas that are not intended to be exposed.

From the above consideration, it would certainly appear that silicone, depending on the compound, could interfere with cement adhesion. Again, just saying "silicone" is not very specific. I don't know how many different formulations are in use, but given their structure it could be thousands. They vary in their properties. That is why one would need to know what silicone is used, and how it behaves when added to leather.

 

[DWFII]



The NASA issues seems to be residual silicones used as release agents for molding parts. The residual then coats other surfaces and interferes with bonding on areas that were not made to have silicone involved. However, this does not directly have anything to do with silicone effects on leather. It does not even have anything to do with the use of silicone at NASA. They do use silicone compounds, the challenge seems to be in uncontrolled introduction of silicones in areas that are not intended to be exposed.

From the above consideration, it would certainly appear that silicone, depending on the compound, could interfere with cement adhesion. Again, just saying "silicone" is not very specific. I don't know how many different formulations are in use, but given their structure it could be thousands. They vary in their properties. That is why one would need to know what silicone is used, and how it behaves when added to leather. 

Certainly the silicone adhesive that Dow puts out for sealing windows is different from the silicone oil that is used both as a release agent and as a waterproofing agent for leather. Many in the Trade use silicone oil as a release agent during lasting.

I have bottles and bottles of both...although after trying it as a release agent I went back to the more Traditional French Chalk. The only difference, AFAICT, being that the waterproofing agent has a solvent in it...to make it penetrate the leather.

 

[dopey]

I always used Nikwax on my hiking boots. It works reasonably well. Over many years, nothing bad has happened to them. But I have no idea what it is or if it is harmful. I suppose my experience tells me it is not harmful. Does anyone else have any thoughts on or experience with Nikwax?