Oils In Leather (Chemistry)

[TinkerTailor]

Current status:

Waylaid by the more or less unanticipated beeswax refining project, and while I was at the thrift store picking up some sacrificial cookware, I found a beautiful sewing machine from 1959 in my wife's favorite color in a '50s Chevy Bel Air-esque design motif complete down to the owners manual, and functional but dirty and in dire need of a tune up. For $20, it was hard not to do it. So while beeswax has been melting, filtering, floating, and cooling these last several evenings, I've been methodically cleaning, lubricating, and adjusting this little jewel to like new (minus a few characterful chips in the lacquer here and there). I still need to find some foot pad things, make a few soft parts, fabricate a replacement for the one broken part, and clean the case, but the hard part is done.

Meanwhile, we went out to dinner last night with my researcher friends, and the physicist and I devised a test methodology. Using TinkerTailor's iron suggestion, today I'll go cut a few scabs of 1/4" mild steel to serve as thermal batteries to keep the temperature constant while the iron cycles. The scabs will be heated to temp on parchment paper over an iron on the appropriate setting (measured with IR thermometer) under a cotton cloth/insulator, and the leather test pieces will be placed between them to be brought up to temp. Wax/oil mixtures will be mixed ahead of time in 25%/50%/75% wax/oil ratios by weight for each test oil plus one sample for neat beeswax for a total of 13. The mixtures will be poured or placed (depending on how I feel they will be best applied, open to suggestions here), and the scabs replaced to keep the leather at the appropriate temperature while the oil/wax mixture penetrates. I'll have to play the saturation by ear unless anyone has any suggestions.

Meanwhile, the net wax yield was 481g/17 ounces/1 lb. 1 oz. of clean, spotless, sunflower yellow, honey scented beeswax. I'd love to post pictures, but this forum seems to have a white list strategy for photo hosting, and google photos is not on it somehow... Who would I have to talk to to get that rectified?

Hit "more reply options", and there is a button to add attachments at the bottom of the msg edit screen. Upload pics there, as many as you want provided the total is under 1.46mb per post. Once you add them once, they appear in your my media button, allowing you to add them to future posts. You can attach small pdf as well, lots of stuff. I dont think the site will show previews of photos hosted elsewhere, but you can link to them and many do. If you do it right, it will show the youtube video window in a post as well. The forum software is pretty good, but kinda quirky at the same time. Don't even bother with the built in search, its as useful as boobs on a boar. Use google. site:leatherworker.net (search)

Edited December 7, 2015 by TinkerTailor

[spectre6000]

It's not a question of how to get photos on here (I'm a software engineer by trade), it's a matter of I don't want to upload them to the forum servers. They're uploaded in a pretty solid and secure location, they should be able to be served from there without unnecessarily restrictive permission settings at the forum admin level. Meanwhile, I'll proceed without photos unless and until something happens there.

This project hasn't died, I start a new job Monday and I've been scrambling to wrap up the current contract between dealing with a finicky client and trying to subcontract an element of it and get that handled and done before I get completely bogged down with the new gig. Additionally, I tend to have a half dozen or so fairly significant projects going on at any one time, so sometimes balls hang in the air a little longer than I'd like. Balls sitting on the table in front of me as I type this include the leather treatment project, a sewing machine restoration project, an automotive fabrication project, a computer hardware project for the new job, and I have an aspiring luthier coming over this afternoon to pick up an acoustic top set I'm gifting him... And that's just the living room coffee table!

Meanwhile, I've been noodling on exactly what and how to divvy up the beeswax and experimental samples. I think the most likely success for my current goals is going to be an olive oil beeswax blend, but I still want to see how raw flax and walnut oils do in terms of the polymerized film on the surface of the leather for another project down the road. I only have a skosh over a pound of beeswax, and I want to be absolutely sure I have a sufficient quantity for the immediate project (locally sourced beeswax that I personally filtered, etc. would just be icing on the cake!), so if I limit the quantity used per sample to an ounce (I'm going to do everything by weight), which may honestly be a bit too generous anyway, and I want to do 25/50/75 percent blends of wax to oil, that pretty much leaves me with about zero (assuming a certain amount of process waste) for the actual project... No bueno. So I think I want to limit the wax blend samples to just that subset of oils (olive) I think will have positive results.

That's pretty much where this project stands. I'm one piece of carved mahogany away from completing one competing project, about two evenings worth of leather carving away from completing another competing project, and that's about the only real competition for this one. I picked up some small glass vessels at the thrift store yesterday (I think they were tea candle glass holder things), and I need to clean them up. I also need to figure out exactly how to suspend them in a pot for double boiling purposes... I'm thinking an aluminum pie tin... The step after that is to distribute the wax into the vessels and get everything blended, then it's time to apply finishes and finally see what's up.

Meanwhile, I need to get back to reviewing this new code base before Monday morning...

[RKCrowe]

Spectre6000,

Your enthusiasm and excitement on this topic is obviously genuine and it really makes me feel smile. I only had basic chemistry, but your explanations were placed on a level that even I could follow... sometimes. I would have liked to observe you and your friends discussion over cinnamon buns. And even more so after the beer came out! Thanks you

[spectre6000]

Sorry for the extended silent period. Life got busy, then I got in a pretty horrific car accident. I'm finally back to where I can get back in the shop a bit, so back to this project!

Am I correct that there have been some changes while I was away? Signing in with Facebook, and... attach images via URL?

Since we're posting photos and to get everything in the same place, here's the beeswax rendering photos:

There was more rendering after this photo, but what I have.

Soooo.... I started by cutting some belly trimmings into rectangular pieces.

Tinker Tailor for the win! I fine tuned my iron to 145° with the IR gun, used a small anvil as a thermal battery, and parchment paper to avoid ruining the iron or the anvil. The target was between 145° and 155°, erring on the low side for safety. As previously stated, that narrow range is pretty much it where the wax will be liquid and the leather won't be ruined. 

I shaved the beeswax block so that I could weigh out the wax for melting.

And I weighed samples out for a total of 20 grams each (a little less than 3/4 ounce) between the wax and oil. I went with olive oil since it's the closest I have to neatsfoot (the status quo) by fatty acid content.

The five samples were neat beeswax, 75/25, 50/50, 25/50, and 15/85 beeswax to oil ratios. The partial sticky notes (somehow I only had one sticky note and the backing pad...) are marked 20, 15, 10, and 5, referring to the grams of beeswax with the unlabeled being 3. The balance was filled with olive oil to a total of 20 grams. Then...

A last minute sanity check, and...

Into the double boiler. This is the smaller of the two pots I bought for this experiment with an aluminum pie tin sliced to form a smaller diameter, perforated, and wrapped in foil so it would stay together under the weight of the glass sample vessels. I think they were glass tea light candle holders, and I got them at the same thrift store I got all the hardware for this experiment. I also found this:

February 1958 Brother portable sewing machine in pretty good, albeit neglected condition. I restored it for my wife for Xmas, and she loved it! Great little thrift store.

Anyway...

The bellies were pretty seriously old... So much so that I have no idea when I got them, from where, or why. They're all slightly different colors, and all pretty dry, so I taped them off to have a bit more control over the control. Then I got to business.

While the wax/oil mixtures were melting, I made go with the oils. The flax oil smells sweet, walnut smells earthy, canola doesn't have much in the way of a smell, and the olive oil smells spicy. I applied multiple coats until it took a little longer for the oil to all be absorbed, and heated the wax-based samples to temp prior to applying the wax oil mixture. This allowed the wax to absorb and not just harden at the surface on contact. I dipped the hot neat wax sample into the hot wax at one end just to see how stiff it got. 

Here's the end result for the day:

Left to right, top to bottom, that's canola oil, 25% wax, 100% wax, flax, 15% wax, 75% wax, walnut, olive, and 50% wax, and the loner is the control (the organization makes more sense if you rotate it to the right 90°, where you get the waxes in decreasing order followed by the oils with the control to the side). It should be noted that the leather was very dry, and the tape pulled some of the top grain off, lightening the appearance.

The higher wax concentration samples proved difficult to apply, and the result appears pretty splotchy. Application with a good aesthetic result would be either difficult or very time consuming and complicated without significant investment in equipment or risking ruining the leather via heat. Additionally, given the role of the oil in the leather, I don't think ultra high beeswax mixtures will allow the fatty acids to do their lubrication and migration song and dance. That said, it seems the heavier wax mixtures would have a fixative effect on any tooling, and this is desirable... On the other end of the spectrum, it's simply too soon to have any idea how the polymerization of the shorter fatty acid chains will affect the end result.

In terms of color, there are variations in the leather sample pieces muddying things up a bit, but all methods and materials darkened the leather considerably at this point with canola as the surprise stand out. I'm not sure why this is. On the neat wax sample, you can see a strip at the end where I heated it up and just dunked it into the hot wax. The heavy saturation reflects less light than the less saturated area. The splotchiness in the 75% wax sample is a prime example of the difficulty applying higher wax concentrations, while the lesser wax mixtures were considerably easier. Time will tell how these effects last over time.

In addition to the application experience, another significant subjective observation is the smell. The walnut oil sample smelled predominantly of walnut; earthy and not unpleasant, but not especially pleasant either. The olive oil sample smelled essentially like olive oil with no real leather aroma; a bit on the spicy side. The canola oil had no real smell at all. The waxed samples smell to varying degrees of sweet honey to spicy olive oil based on their respective concentrations without much leather smell. The flax oil is sweet on its own, and in the leather has a wonderful smell that stands out above the rest. The leather by itself didn't smell especially strong of anything (it's old), but the flax oil made for a very good leather smell beyond expectation. I don't know why this is, but based on reports of fish oils smelling especially like leather, it makes me wonder exactly what's going on there. They both are notoriously high in omega 3 fatty acids (mid-length polyunsaturated), so maybe there's something going on there... Who knows.

Finally, I allowed the wax mixtures to cool and harden. I expected the neat wax to harden like the rest of the wax, and that the lesser samples would soften considerably to the point that the 15% sample would barely be any more viscous than the oil, but surprisingly they all hardened save the 15% sample.

I stuck my finger in each one, and while the 25% sample gave a tiny bit where some bubbles had formed but was otherwise solid, only the 15% mixture really gave at all. Some water had splashed in from the boiling water, and it squished out from this sample as well. As an aside, it makes good lip balm. Some fiddling with other oils could make for a pretty awesome home made Burt's Bees replacement (the olive oil just lacks the good smell)! 

So... Where does that leave us? The 15%, 25%, and to a lesser extent 50% wax mixtures were easy enough to apply as to be viable. Heavier than that was too difficult using these methods. The liquid oils are obviously easy to apply, but time will tell how they do over time. I like the idea of the wax fixing tooling, but have some concern at what it will do over time as the oils break down and subsequently migrate... Or would the wax prevent migration? Additionally, wax is known to stiffen leather, but with enough oil it softens considerably... The question is how this affects things when it's suspended between the leather fibers. How does it affect things as the oil breaks down? The same question can be asked of the polymerization from the shorter fatty acid chains oxidizing. Does this form a barrier that makes subsequent applications of oil difficult or even impossible? The smooth surface that results from the polymer film would make for a good dark color, this would be even more the case when combined with a percentage of wax. The sweet smell of the wax combined with the sweet leather smell from the flax oil and the shine and tooling fixation could be awesome! It could also ultimately shorten the lifespan of the work... It would probably be years before the effects were noticeable, and they may not happen at all, but it is something outside the norm about which I can't find any information.

The next phase is to wait and see what happens over time... Months... Years... I'm not that patient for the immediate projects, so I'll have to decide on something sooner. The next thing I'd like to try is some lighter wax mixtures with other oils. The flax is especially interesting from the perspective of the eventual high gloss polymer finish and dark color it would ultimately result in, but I want to get some longer carbon chains in there too for a bit better lubricity over a longer period of time. That might ultimately mean a multi-phase finish. Maybe a light oiling or two front and back with olive oil, then finish with a heavy application of a 15-25% beeswax/flax oil mixture. That would help the tooling stay crisp, eventually result in a very polished finish, and the sweet smell of the wax and the sweet leather smell will likely be a pretty killer combo. I might investigate another oil or two in there for fun too when I go for the second round... We'll see.

[stelmackr]

No pictures were visible to me.

[spectre6000]

OK. I think I figured it out. I can't go back and edit the previous post, but I'll repost it with the photos correctly linked. I think it was my fault. Stand by.

Maybe a mod can do some mod magicks and delete the dupe, move things around, or whatever else makes sense.

Edited April 4, 2016 by spectre6000

[spectre6000]

Sorry for the extended silent period. Life got busy, then I got in a pretty horrific car accident. I'm finally back to where I can get back in the shop a bit, so back to this project!

Am I correct that there have been some changes while I was away? Signing in with Facebook, and... attach images via URL?

Since we're posting photos and to get everything in the same place, here's the beeswax rendering photos:

There was more rendering after this photo, but what I have.

Soooo.... I started by cutting some belly trimmings into rectangular pieces.

Tinker Tailor for the win! I fine tuned my iron to 145° with the IR gun, used a small anvil as a thermal battery, and parchment paper to avoid ruining the iron or the anvil. The target was between 145° and 155°, erring on the low side for safety. As previously stated, that narrow range is pretty much it where the wax will be liquid and the leather won't be ruined. 

I shaved the beeswax block so that I could weigh out the wax for melting.

And I weighed samples out for a total of 20 grams each (a little less than 3/4 ounce) between the wax and oil. I went with olive oil since it's the closest I have to neatsfoot (the status quo) by fatty acid content.

The five samples were neat beeswax, 75/25, 50/50, 25/50, and 15/85 beeswax to oil ratios. The partial sticky notes (somehow I only had one sticky note and the backing pad...) are marked 20, 15, 10, and 5, referring to the grams of beeswax with the unlabeled being 3. The balance was filled with olive oil to a total of 20 grams. Then...

A last minute sanity check, and...

Into the double boiler. This is the smaller of the two pots I bought for this experiment with an aluminum pie tin sliced to form a smaller diameter, perforated, and wrapped in foil so it would stay together under the weight of the glass sample vessels. I think they were glass tea light candle holders, and I got them at the same thrift store I got all the hardware for this experiment. I also found this:

February 1958 Brother portable sewing machine in pretty good, albeit neglected condition. I restored it for my wife for Xmas, and she loved it! Great little thrift store.

Anyway...

The bellies were pretty seriously old... So much so that I have no idea when I got them, from where, or why. They're all slightly different colors, and all pretty dry, so I taped them off to have a bit more control over the control. Then I got to business.

While the wax/oil mixtures were melting, I made go with the oils. The flax oil smells sweet, walnut smells earthy, canola doesn't have much in the way of a smell, and the olive oil smells spicy. I applied multiple coats until it took a little longer for the oil to all be absorbed, and heated the wax-based samples to temp prior to applying the wax oil mixture. This allowed the wax to absorb and not just harden at the surface on contact. I dipped the hot neat wax sample into the hot wax at one end just to see how stiff it got. 

Here's the end result for the day:

Left to right, top to bottom, that's canola oil, 25% wax, 100% wax, flax, 15% wax, 75% wax, walnut, olive, and 50% wax, and the loner is the control (the organization makes more sense if you rotate it to the right 90°, where you get the waxes in decreasing order followed by the oils with the control to the side). It should be noted that the leather was very dry, and the tape pulled some of the top grain off, lightening the appearance.

The higher wax concentration samples proved difficult to apply, and the result appears pretty splotchy. Application with a good aesthetic result would be either difficult or very time consuming and complicated without significant investment in equipment or risking ruining the leather via heat. Additionally, given the role of the oil in the leather, I don't think ultra high beeswax mixtures will allow the fatty acids to do their lubrication and migration song and dance. That said, it seems the heavier wax mixtures would have a fixative effect on any tooling, and this is desirable... On the other end of the spectrum, it's simply too soon to have any idea how the polymerization of the shorter fatty acid chains will affect the end result.

In terms of color, there are variations in the leather sample pieces muddying things up a bit, but all methods and materials darkened the leather considerably at this point with canola as the surprise stand out. I'm not sure why this is. On the neat wax sample, you can see a strip at the end where I heated it up and just dunked it into the hot wax. The heavy saturation reflects less light than the less saturated area. The splotchiness in the 75% wax sample is a prime example of the difficulty applying higher wax concentrations, while the lesser wax mixtures were considerably easier. Time will tell how these effects last over time.

In addition to the application experience, another significant subjective observation is the smell. The walnut oil sample smelled predominantly of walnut; earthy and not unpleasant, but not especially pleasant either. The olive oil sample smelled essentially like olive oil with no real leather aroma; a bit on the spicy side. The canola oil had no real smell at all. The waxed samples smell to varying degrees of sweet honey to spicy olive oil based on their respective concentrations without much leather smell. The flax oil is sweet on its own, and in the leather has a wonderful smell that stands out above the rest. The leather by itself didn't smell especially strong of anything (it's old), but the flax oil made for a very good leather smell beyond expectation. I don't know why this is, but based on reports of fish oils smelling especially like leather, it makes me wonder exactly what's going on there. They both are notoriously high in omega 3 fatty acids (mid-length polyunsaturated), so maybe there's something going on there... Who knows.

Finally, I allowed the wax mixtures to cool and harden. I expected the neat wax to harden like the rest of the wax, and that the lesser samples would soften considerably to the point that the 15% sample would barely be any more viscous than the oil, but surprisingly they all hardened save the 15% sample.

I stuck my finger in each one, and while the 25% sample gave a tiny bit where some bubbles had formed but was otherwise solid, only the 15% mixture really gave at all. Some water had splashed in from the boiling water, and it squished out from this sample as well. As an aside, it makes good lip balm. Some fiddling with other oils could make for a pretty awesome home made Burt's Bees replacement (the olive oil just lacks the good smell)! 

So... Where does that leave us? The 15%, 25%, and to a lesser extent 50% wax mixtures were easy enough to apply as to be viable. Heavier than that was too difficult using these methods. The liquid oils are obviously easy to apply, but time will tell how they do over time. I like the idea of the wax fixing tooling, but have some concern at what it will do over time as the oils break down and subsequently migrate... Or would the wax prevent migration? Additionally, wax is known to stiffen leather, but with enough oil it softens considerably... The question is how this affects things when it's suspended between the leather fibers. How does it affect things as the oil breaks down? The same question can be asked of the polymerization from the shorter fatty acid chains oxidizing. Does this form a barrier that makes subsequent applications of oil difficult or even impossible? The smooth surface that results from the polymer film would make for a good dark color, this would be even more the case when combined with a percentage of wax. The sweet smell of the wax combined with the sweet leather smell from the flax oil and the shine and tooling fixation could be awesome! It could also ultimately shorten the lifespan of the work... It would probably be years before the effects were noticeable, and they may not happen at all, but it is something outside the norm about which I can't find any information.

The next phase is to wait and see what happens over time... Months... Years... I'm not that patient for the immediate projects, so I'll have to decide on something sooner. The next thing I'd like to try is some lighter wax mixtures with other oils. The flax is especially interesting from the perspective of the eventual high gloss polymer finish and dark color it would ultimately result in, but I want to get some longer carbon chains in there too for a bit better lubricity over a longer period of time. That might ultimately mean a multi-phase finish. Maybe a light oiling or two front and back with olive oil, then finish with a heavy application of a 15-25% beeswax/flax oil mixture. That would help the tooling stay crisp, eventually result in a very polished finish, and the sweet smell of the wax and the sweet leather smell will likely be a pretty killer combo. I might investigate another oil or two in there for fun too when I go for the second round... We'll see.

[spectre6000]

Part two of experiment execution:

A little over 24 hours has passed. The smell of the oils had more or less disappeared. The canola oil is still slightly darker than the other oils, but the colors have pretty much evened out save the heavier wax mixtures. I inspected the back of the patches, and noticed a pretty interesting trend: the lighter oils, especially the canola oil, had penetrated through to the back of the patches. This was unexpected, but not at all surprising. The implications have potential import in the next phase. I reapplied the oils for a second round. I'll probably do three total and call it good on this set.

In preparation for the next phase, I purchased a floral, pleasant smelling blend of essential oils. Rose oil was completely unavailable, and would have been insanely expensive at any rate. I don't recall the exact blend, and I haven't done any research on the makeup of the oil combination, but I don't think it's of special import. This morning over breakfast, I went back and re-read the thread and realized I forgot a step; I neglected to case the leather ahead of time, and this combined with the especially dry nature of the leather means less and less even penetration. The idea with the essential oils is to see if I can impart some especially pleasant smell to the leather. Given the loss of smell of the other oils over as little as 24 hours, I doubt very much it will, but it's in the plan and why not. I'm hoping to emulsify the essential oils into some water, and use that to case the leather. Ideally this should distribute the oils pretty evenly throughout the leather, but only in very small quantities. Again, not expecting much, but that's the plan. From there, I find the penetration of the lighter oils interesting and potentially useful. I think some stratification in the choice of oils applied in stages could have an overall positive effect. More on this later.

Finally, I was thinking about the wax mixtures. I was thinking it might be nice to use some wax to set the tooling and provide a little extra crispness and staying power. The downside to this is that it stiffens the piece overall, and could have a negative effect on longevity. The other side of the coin is that it seals the leather, and can potentially be used to shine it up a bit. Combined with some lighter fatty acid byproducts, it could result in a really nice finish over time. These two goals are pretty much counter indicated though, and I'm thinking the latter has more merit overall. It further dawned on me that the oil lowers the melting point of the wax (duh!), and I hadn't accounted for that in any way. In the event the wax/oil mixture is used for something clothing oriented (like a belt), the wearer's body heat would completely nullify the fixative properties of the wax. The 15% wax mixture is so soft at room temperature, that there's no fixing whatsoever, and I'm not sure it would have any benefit outside of sealing out moisture; this could also seal out future oilings. The 25% mixture is fairly stiff at room temperature, but held in my hand for a few minutes resulted in it turning to a consistency very much like the 15% mixture at room temperature. This could be a good middle ground for non-wearable tooled leather pieces to set the tooling a bit without it being too difficult or detrimental. The 50% mixture softened up a bit as well, but not quite as much. When suspended in the leather, this could be the golden ticket for fixing tooling with the application technique I used. The downside is that it's somewhat difficult to apply evenly, but I would say it can probably be done successfully. I'll have to mess with that one a little more. 75% wax was hard as hard can be no matter what. 

At any rate, more experimentation is scheduled. Still refining the strategy. It's going to be a long time before anything conclusive can be decided in terms of whether or not any of this has results that are in any way superior or even different from the status quo, but it's a lot of fun exploring it!

[spectre6000]

An update on this for the one or two people still following this little vanity project...:

I unpacked the treated samples detailed above after moving recently, and discovered the fatty acid composition of the beeswax must have some shorter carbon chains than I initially thought, or ultra long carbon chains in the wax are not as stable as I thought and are also subject to the sort of precipitates that result in spue/spew. The heavier (50% and greater) beeswax concentrations are all showing spue/spew, with the higher concentrations exhibiting more noticeable effects. These samples have not been handled hardly at all, and I'm sure regular use would rub the spue/spew away pretty handily such that it would never be noticeable. 

Meanwhile, I've also been experimenting heavily with oil treatments in various combinations, orders, methods, etc. I think I've landed on some pretty stellar results! There's a time aspect that I can't really control for due to lack of the proper equipment (time machines are expensive), but I am extremely confident in the long term viability of my methods. Looks and feels fantastic too! I'm still working on what I hope will be the final incarnation for regular use, but my wife is very excited for the belt she's getting out of the current iteration of this little exercise (I got tired of all the squares of belly scraps)!

[CalSheaths]

Thank you for conducting this research/experiment and this update. Very interesting.