Best method for japanning

[FenceFurniture]

Rust prevention is excellent

Yes, this was mentioned in Jameel's blog, and again, think of a cast iron frying pan - when they have the brown coating they don't rust - it's not so much keeping the air away from the CI as keeping the moisture away and I doubt that any moisture in the air would penetrate, even though oxygen may.

What will all the heating and cooling do to the old cast iron?

Think of cast iron frypan.

I agree Frank. When I'm cooking, I use an infrared thermometer to heat up the frying pan to 140-150 C and then add the oil. There have been numerous times when I've been distracted and it's gone way over, up to 230 C once or twice. No effect on the pans, and these are Scanpan which are Aluminium and you'd have to think that Cast Iron (particularly as old as your plane) would be much tougher.

However, it's just as well to be safe, so I'll send a PM to someone who I think will have the answer, and ask them to stick their head in here.

[FenceFurniture]

Couple of things I meant to mention in the previous post. Earlier I said BLO was used, but apparently it's just raw Linseed (Flax).

When I was trawling around for some fully annealed Cast Iron a few weeks ago (for Honing Blocks) the question came up about annealing temperatures, and as I recall 700 deg C was about the mark. That would mean that the oven certainly won't soften the CI, so really all that remains to resolve is any potential warping/cracking issues.

Have sent that PM.

[Brobdingnagian]

How cast iron will behave will depend on how it has been heat treated in the past.

The major changes in dimensions occur with cast iron when you heat it hot enough that it is able to change the crystal structures in the iron, and by major I mean ones that you can see.

I will specifically keep my comments to Ductile Iron as that is the most likely choice for a iron plane body.

If you keep the plane bellow 240°C you are not going to change any of the crystal structures in the iron and are not going to have any major distortions. Stress reliving temperatures are 510°C to 675°C depending on the alloy composition. The Austenitizing temperatures are between 845°C and 925°C. Austempering ranges are between 240-440°C. Bellow 375°C elongation is bellow 4%

But if you want to play it super safe then I would suggest that you stay bellow 240°C and cool the plane in the closed oven down till its is warm to the touch <~55°C. This will have the least thermal shock and reduce the risk even further and effect no change in the microstructures.

FYI bellow 290C is considered safe to air cool. But your not in a production environment so efficiency is not you major concern.

-Josh

Edit:
There are a lot of different cast irons, The 240°C temperature I state here is safe as houses, even if it has been specially heat treated for particular set of properties it will not be effected unless it is a very special alloy. You may still get some minor distortion but nothing a swipe of a file or a minute on a lapping plate would not cure.

[FenceFurniture]

Thanks for that Josh. How do you reckon the plane will look?

Eddie - there's nowhere to hide now.

[Brobdingnagian]

Thanks for that Josh. How do you reckon the plane will look?

Bags of Awesomeness. Do it.

[Dengue]

So, FF, after all that discussion, how are you going to actually do it?

[FenceFurniture]

So, FF, after all that discussion, how are you going to actually do it?

Well I've got an old crapper that I'll clean up and polish polish parts of and do a test run as per the instructions on the Benchcrafted blog

[snafuspyramid]

Alright, well I'll await the results with eager anticipation before I try sticking this rare plane in the oven. I'm going to need to do a lot more surface prep for this method anyway so it'll be a while before I'm there.

Do you reckon that 200 degrees celsius would polymerise the oil adequately?

I will try and track down some writing about cooking planes in the context of "japanning" them - I know a number of people have done this and am curious about the results regarding stress to the casting.

[snafuspyramid]

Well here is something from Hans Brunner making me think this ain't a new idea...
"
Obviously originates from Japan and describes a glossy, highly polished finish derived from natural resins, usually with a black background, found on many Japanese objects. Became fashionable in Europe late1800s/early 1900s with a "modern" concoction of gum shellac, linseed oil and a few toxic nasties like red lead. A more recent version includes the use of linseed oil and asphaltum, still used to preserve etched plates but with more warnings on the label than your child's teddy bear. When you read: fatal when swallowed on a bottle you have to be really keen to brew up a new coat for your Stanley jointer! Some tool guys swear by the use of linseed oil repeatedly burned into the plane then polished. Why bother, there are perfectly good paints available in cans. I assume it's the constantly poor results of these re-japanning attempts that keeps the alchemists trying. I don't mind re-painted tools. A paint job might interfere with the sensitivities of many collectors but never slowed down a jointer in the hands of a craftsman."

[FenceFurniture]

I wouldn't wait for me - it's very much a background project that could be months away.

For the temp I'd go as high as you dare. Josh says completely safe at 240 so I reckon that's where I'd go with your plane. For mine I'll probably go 250-260.

I think Hans is missing the point of the lustrous look if he likes the look of paint. Paint is for ordinary people.

[snafuspyramid]

Dunno.

Have been giving it more thought.

Sure, it would make the plane look prettier. I'll accept that.

But, it would take an enormous amount of time (and gas). I'm not really sure when I'd be in the house long enough to monopolise the oven for three and a half hours at a stretch, certainly not on five occasions.

I'd feel different if I were retired, but that's probably fifty years away.

Using the japan / paint stuff would take about fifteen minutes (five minutes per coat) and be functionally identical.

Of course I'd happily send it to you if you want to do it for me?

[FenceFurniture]

Of course I'd happily send it to you if you want to do it for me?

Sure thing, but you should be aware that very few tools leave here. Very few indeed. In fact the nicer they are, the less the chance. But I'll PM you my address if you like (garn, take a chance).

[snafuspyramid]

Very few tools leave here. Very few indeed. In fact the nicer they are, the less the chance.

What, you mean that if somebody left one of these at your house by mistake, for example, and then forgot where they'd put them, you'd perhaps maybe accidentally neglect to return them?

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What's the world coming to?

On the topic of the whole cookin' flax oil thing, I've got a nasty feeling that it's one of those things where it'll just bug me until I do it.

Like flattening the soles of my planes. I don't want to do it, I probably don't need to do it, but somehow once the idea is in my head it just bugs me until I relent.

Confound you for putting the idea in my head...

[snafuspyramid]

Why not just use BLO without cooking? Should come to more or less the same thing.

[FenceFurniture]

Why not just use BLO without cooking? Should come to more or less the same thing.

I doubt it would be as hard or durable, and there may be a difference in colour.

Ever tried to get that gunk of a pan? Pretty damn difficult! Oh, that's right, you're not allowed in the kitchen.