Was my 1948 9A's bed "japanned?"
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  1. #1
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    Default Was my 1948 9A's bed "japanned?"

    My 1948 9A's bed appears to have been japanned.

    If not, I wonder what the thick coating -- missing in spots -- is.

    Years ago at <http://www.lathes.co.uk/southbend9-inch/>, I found a great history of the 9 inch lathe. It contains this interesting note:

    Oddly, during 1947 (at a time that seems to have coincided with a new number system in march of that year) , a batch of lathes was produced that might be described as an "interim" model with longer, convex-ended feet and a bed that must have been from a new mould. This bed, which was used for a short production run only, lacked the pronounced rib along the lower edges, had a "square" profile in cross section (in comparison to the original round style) and (most distinctive of all) the word South Bed cast into the top face of two bed cross-ribs. After this the later style feet were adopted and the bed revered to the older style.
    My lathe is apparently one of those with the odd-ball bed, based on the "South Bend" cast into two of the cross-ribs.

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    I also had one of those transition lathes. It was regular gray enamel under various repaints. Under that was the notorious south bend 'filler' a weird, grayish putty material that has been on the few SBs I have stripped. This stuff does not respond to chemical (or electrolytic) stripping very well, and must be mechanically removed. Generally I try to leave it.

    allan

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    It would be helpful if you could post a photo or two of the lathe finish. Likely it was not Japaned. This style of coating is actually a mineralized finish created by mixing Gilsonite (asphaultum) with lamp black (carbon) for color, and Lindseed oil, then melting, dissolving, and spraying onto the surface of the lathe. Then baking at 400*F until the formulation crystallized and dried hard.

    Most Japanned surfaces were black colored, and were applied from turn of the century up through around 1920-25, when more modern oil based metal under coater and paint formulations became widely available. The finish is extremely hard and durable, with no undercoat. Almost nobody was using Gilsonite as a machine tool finish in 1949.

    Side note, Henry Ford pioneered Gilsonite as an undercoat for his early day automobiles, as the crystalline structure of the asphaultum material offers superb abrasion resistance and imperviousness to water penetration. He apparently borrowed the idea from machine tool manufacturers, who had already used this extensively on Lathes and mills etc.

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    Here are a couple photos of the ugly crud on my lathe bed. I know I should probably leave it alone, but I can't.

    bed-crud-1.jpg

    bed-crud-2.jpg

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    Quote Originally Posted by Yan Wo View Post
    Here are a couple photos of the ugly crud on my lathe bed. I know I should probably leave it alone, but I can't.

    bed-crud-1.jpg

    bed-crud-2.jpg
    Oh yeah! I couldn't let that stand either.

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    Quote Originally Posted by Yan Wo View Post
    If not, I wonder what the thick coating -- missing in spots -- is.
    It looks to me like a build up of layers of paint applied over the years. Chip off a piece and polish the edge a bit and look at the edge with a magnifier. See if you can make out different colors. If it was japanned, it wouldn't be that thick. Japanning was used mainly to fill in defects in the castings.

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    Nasty stuff, what ever it is. Surface looks like oil based enamel paint. When you go to strip it or, wear a mask and maybe keep it damp/wet to keep the lead dust down. All the paint in those days had a significant lead content- lead made it shinny.

    What’s underneath is anybodies guess. Maybe an early form of auto body putty. Now saturated and dried out many times with machine oil. Finally crumbling away such as you see in the photo.

    Chip and strip, repeat, repeat... eventually you’ll have a nice looking lathe.

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    Interestingly enough, nothing else on the lathe is covered with this nasty glop. Thank goodness!

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    Quote Originally Posted by SLK001 View Post
    It looks to me like a build up of layers of paint applied over the years. Chip off a piece and polish the edge a bit and look at the edge with a magnifier. See if you can make out different colors. If it was japanned, it wouldn't be that thick. Japanning was used mainly to fill in defects in the castings.
    I examined a chip of the glop using my electron microscope (OK, I just used my myopic microscopic vision), and confirmed there's no built-up layers of paint.

    The substance -- whatever it is -- is soluble in MEK. When smeared around, it bonds well to the cast iron when the MEK evaporates.

    I'm not going to use any more MEK for fear of reducing the few years I have left.

    I have been successful in grinding it off, wearing a mask while doing so.

    The glop is very effective at preventing rust. I have found only a couple tiny traces of rust under the coating.

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    After watching this video on japanning, and smelling asphalt while grinding and sanding, I am convinced my lathe's bed was, indeed, japanned. I looks like the whole bed was immersed in a vat of the glop before machining. No other parts of the lathe, including the bed feet, are similarly treated. Weird!


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