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Japanning a Straight Edge

M.B. Naegle

Diamond
Joined
Feb 7, 2011
Location
Conroe, TX USA
Has anyone ever done it?

I ask as I have a couple new straight edge's and one re-machined one that are going to need a coating of some kind. My 24" I painted in light blue hammered-tone to match my old Biax. It's held up well enough but has gotten a few chips over the last 2-3 years and the light blue color doesn't stay clean. Part of it is also that I didn't sand the rough casting down that much so the bumpy painted surface while providing grip, also lets dirt stick to it. So sanding these next straight edges a little better would help.

I'm wondering if a thick Japanned finish would be more durable than a thick paint? I've read that it's labor intensive (like scraping!:)), to the point that it almost isn't worth the effort unless you are trying to exactly recreate the finish of an old tool for a museum, BUT... if it is more durable, I might give it a shot. Of all the old hand tools I've worked with that still have the smooth black Japanned finish, some were chipped and cracked, but most seemed like it was a bulletproof finish, or at least much more abrasion resistant.

The straight edges I'll be doing are the "generic" curved back type that I asked about here: https://www.practicalmachinist.com/vb/machine-reconditioning-scraping-and-inspection/identifying-straight-edge-patterns-357498/.

I found a DIY formula here: ElMorain Japan, that is essentially Asphaltum, Turpentine, and Linseed Oil that is brushed on thin and allowed to get gummy between coats, then baked. I have all the materials for it, with the exception of an oven that will fit the 48" casting.
 
The only straightedge I have painted so far, I painted it light gray. The rationale is to paint it a light color, which will absorb less heat from radiation.
Yes, it gets dirty at the point that some blue cannot be removed anymore from the paint. But, being off-the-shelf oil-based Rustoleum, it's east enough to give it another coat, if I were bothered more by the look that by its functionality.

Paolo
 
It's true that light paint absorbs less than dark paint, but the difference is less than you might think. They both absorb quite a lot of IR in spite of the visible difference. I don't have a good answer on paint. IMO, modern paint isn't as good as the old stuff and it's near impossible to buy a baking enamel anymore. I think they call it "stovable" enamel overseas. I want a can of what they used to paint black Stanley planes with back in the day!
 
I just used a can of Rustoleum in a medium blue similar to DyeKem. If I’m worried about my body heat radiating into the SE, I just wrap some aluminum foil over the bow and verticals. Not sure how much difference that makes, but I feel better ;-). I do think the foil wrap is likely to be significantly better at reflecting heat than any paint might be.


If I were wanting to put the best available paint on a machine or SE, I’d be asking my car-enthusiast friends fo make recommendations. When I was recently painting an aluminum pattern for my 18” prism/level/straight edge, they recommended a two-part polyester primer paint. Though it was very expensive, it sprayed on beautifully and sanded better by far than anything I had previously used. Because of special pattern molding factors, I used my usual lacquer as a finish coat. But, for maximum durability and appearance, I’d strongly consider two-part polyester finish coats as well.

BTW, the polyester two-parts are relatively benign from a safety stand point, in marked contrast to catalyzed polyurethanes which are great paints, but should be sprayed only with proper PPE and, optimally, a full-on spray booth or maybe outdoors.

Denis
 
Two or three years ago I machined and scraped one of Richard King's 24" straightedges. I got it sandblasted and powder-coated gray before the rough and finish machining. It was quick, easy, and inexpensive, and the surface is tough and resistant to solvents, bluing, and sweat.

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If I was going to do it again, I probably would have done the rough machining first, then painted it, then done the finish machining. Half an hour with a die grinder to smooth it over first probably would also have been a good idea. Next time...
 
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You can just buy "Hammer Tone" spray paints. They are quite good. I use them all the time. Great "rust preventers" and stick to just about any clean and dry metal surface.

Limited color choice though.// I like the charcoal best ;-)

And if you were concerned about RADIATIVE heat transfer, You would leave the surface bare.

If you are worried about conductive heat transfer, you would put on many coats of paint.
 
You can just buy "Hammer Tone" spray paints. They are quite good. I use them all the time. Great "rust preventers" and stick to just about any clean and dry metal surface.

Limited color choice though.// I like the charcoal best ;-)

And if you were concerned about RADIATIVE heat transfer, You would leave the surface bare.

If you are worried about conductive heat transfer, you would put on many coats of paint.

Yes I agree they're durable. As I noted in the first post, I've used light blue hammered tone paint on a previous straight edge and it's held up well, but still has gotten chips here and there. Easy enough to touch up, but looking at other coatings.

I'm not concerned with the paint providing so much of a heat barrier. While it can to a certain degree, I don't think it's nearly enough to worry about. IMO the paint is primarily to prevent rust, make cleaning easier, and add to the overall pride you have in the tool. That part's a mind game, but in general I think our minds have more trust in a tool that is clean and looks nice as opposed to something rough, dirty, or painted an odd color. I'm a fan of blacks and grey's, unless I know the OEM did something else like a green or blue. Then my OCD kicks in and I want it to be "correct" so it's accuracy will double.:dunce:

IMO, when working in standard scraping conditions, the heat from your hands won't effect the print unless you are particularly hot blooded and keeping your hands on the bare casting for long periods of time. For most of my prints, the time from picking up the straight edge, rubbing it on the surface, and then setting it back down, is often a minute or less. Any longer and I'd rather suspend the straight edge from a hoist. If you're scraping for higher accuracy on a Moore or Monarch for example, then yes hand heat could effect the straightness of the straight edge within that tolerance, but that's easily solved by holding it with gloves, rags, or wood handles. The straight edges I'm working on at the moment will get some wood blocks bolted on as I want a flat surface on the back to allow them to rest upside down to spread ink.

The heat from your hands is one thing, the heat from your environment is another. But even with that, I think the best option is to keep it out of direct sunlight and keep it in the same environment as the job you are scraping, or at least get it there 12 or so hours before so it can normalize before you start printing. IMO, distortion has less to do if the casting is 50 degree's or 150 degree's and more to do with how uniform that heat is in the casting. In that regard, a paint that will NOT inhibit heat transfer (on no paint as you suggest) would be better so that the casting temp can normalize to the ambient temp faster.
 
traditional paint finishes for industry

Rust Cap is (was?) a brand of hammertone paint with quite a few colors. It came in rattle cans, pints, quarts and gallons. More to the point however was it was great around oils and slovents. Last time I purchased it was aerosol cans in red, lt blue, dark blue and lt green from McMaster Carr.

And while we're on the paint subject, B&S used to paint all their metal cases in an international blue "wrinkle". Vintage JAN electronics was always either OD Green, gray or dark charcoal "wrinkle" Does anyone still make "wrinkle" paints?

Kent
 
Rust Cap is (was?) a brand of hammertone paint with quite a few colors. It came in rattle cans, pints, quarts and gallons. More to the point however was it was great around oils and slovents. Last time I purchased it was aerosol cans in red, lt blue, dark blue and lt green from McMaster Carr.

And while we're on the paint subject, B&S used to paint all their metal cases in an international blue "wrinkle". Vintage JAN electronics was always either OD Green, gray or dark charcoal "wrinkle" Does anyone still make "wrinkle" paints?

Kent

I know you can buy wrinkle paint in rattle cans. We've use it for some items, but you have to be careful to get a nice even coat over the whole thing. Too thin and it doesn't wrinkle up. I also pre-heat the parts and then put them back in the oven after painting. It's pretty tough stuff, but I find that on castings it sometimes doesn't come out right as the line between having it thick enough to wrinkle and not so much that it runs can be hard to gauge on a castings irregular surface.
 
Another thread reminded me that I haven't updated this project. I've got Japaning building up on the three straight edges noted previously.

After about 4 coats of Japaning, I did a final bake on the 4 foot SE by leaving it close to a large camp fire behind the shop. It got hot enough to darken the bare metal surfaces, but the scraping isn't done yet so no biggie. The coating is hard as glass, but I'm considering adding a few more layers to smooth it up some more before I go back to scraping. The other two 18" SE's almost have enough layers to go in an oven. Their castings were smoother to begin with so the Japaning is coming out much smoother.

Can't say I'd choose this coating process for all my SE's, but I like it. It's durable and looks sharpe, but the labor and patience price tag is high. It seems that most over-the-counter black paints have a blue/purple tint or base, while this stuff is a brown tint.

Unrelated, but for all three of these SE's I'm making leather "shoes" to protect the flats, further promoting the old-industy skills/materials theme.

Pictures incoming....
 
I know you can buy wrinkle paint in rattle cans. We've use it for some items, but you have to be careful to get a nice even coat over the whole thing. Too thin and it doesn't wrinkle up. I also pre-heat the parts and then put them back in the oven after painting. It's pretty tough stuff, but I find that on castings it sometimes doesn't come out right as the line between having it thick enough to wrinkle and not so much that it runs can be hard to gauge on a castings irregular surface.

VHT makes a decent black wrinkle paint in a spray can that works pretty well. I just used some on a safe I had to cut into due to electric lock failure.

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I've also used wrinkle powder coat; that worked pretty well also.
 
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Red, and brown wrinkle are available to match Kennedy toolboxes. The brown is a good match for atwater kent radio stuff. An example of black wrinkle:
 

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Brushing the stuff on in a horizontal plane seems to work best to get a smooth coat without drips. Thickening the mixture would help, potentially by reducing it over some heat. I think one more coat on these two castings will be enough to put them in the oven to cure.
 
The only thing that I could add, is a light gray color or similar , at least for me, would not work, cause I would absolutely transfer the Prussian Blue from my hands or whatever, even if careful, and stain the paint, and it would eventually look like shit.
 








 
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