I figured out how to fix the stubborn chalky finish with my leather hardening technique

[Gullex]

Good morning everyone.

In the photo, on the left is the first leather bottle I made using the hardening technique I developed and wrote up. On the right, the second bottle.

In my article linked above, I recommended cleaning up excess stearic acid from the piece using a heat gun and rag. I have learned this leads to the inferior, chalky-looking finish seen on the left hand piece. I think what happens is the heat melts the acid out of the surface fibers of the leather, and so you get that off-looking appearance.

I had the same issue with the piece on the right. I first tried taking some melted stearic acid and wiping it back on the chalky parts, melting it in with the heat gun, and wiping it off more carefully so as not to absorb surface sterate. That didn't work either, still got the same finish. I tried every top-coat I had to stop that chalky look- resolene, tan-kote, carnauba creme, leather sheen, waxes, etc. Nothing worked- a day later, the haze was back.

So what I finally found was, you just have to get a bunch of wads of paper towels ready, and start wiping it down *immediately* after it comes out of the stearic acid bath, which is tough because it's going to be 200F. 

What I did with the bottle on the right, was lift it from the pot with a stick, and gently grab a corner. Slowly lift the whole thing out of the pot and let the stearate from the inside drain out, and give it a few seconds to stop dripping so much. Move it over a tray or towel or something as soon as you can, you really don't want to risk dropping your leather item back in the molten stearic acid and splashing that stuff on yourself, will make for a nasty burn. Once the dripping is basically done, swing it briskly overhead or give it a few fast shakes to get off excess acid (DON'T do this outside in the winter- it will crystallize immediately and ruin the finish), and then start wiping it down quickly, over and over, and keep rotating it at a good pace because stearic acid will start to seep out of the leather. 

Keep rotating it to keep as much stearate in the leather, keep wiping. In a few minutes it will cool enough that the stearate no longer seeps out. Give it a few more wipes, and stick it in the freezer for a few minutes to harden.

If you mess up, just stick the bad spot back into the stearic acid bath to re-melt, then pull it back out and start wiping again.

After hardening in the freezer a few minutes, polish it up with the grain side of a scrap of veg-tan.

The edges polish up *incredibly* well with nothing but sandpaper- the second photo is the edge of that bottle taken to 7,000 grit, then buffed with a soft cloth. No burnishing agent needed. (You *will* go through lots of sandpaper- the stearic acid gums it up quickly).

I also said in the article that this stuff might even compare to wood in hardness/toughness. After working with it more, I can say confidently it's harder/tougher than *most* woods. The rim of the bottle is only 3mm thick, and I can't crush it by squeezing with my hands as hard as possible. I can think of plenty of woods that would be easy as pie to crush a 3mm thickness of.

Anyway, I'll be doing an article on making the flask and on hardening updates in the future. Keep an eye out!

Oops! The forum won't let me add another photo, they're to big. Here's a link to the polished edge instead:

[Northmount]

@Gullex Oops! The forum won't let me add another photo, they're to big.  

See this post

Tom