Engineer's Blue

I found that "permanent" markers tend to wash off with my non-aqueos cutting fluid. The, I presume, shellac based marking fluid stays put until wiped off with meths. Reeves and Blackgates both sell little bottles.

Rod

Me too. I found that they also tend to wear off rather easily with handling Nor do they go on particularly well in the first place on, possibly oily, material unless you clean it with a solvent first. It can be "awkward" if you've lost your line part-way through making the part.

Given the relatively small cost of the real stuff, it seems a pity to cut corners on it.

As an apprentice, marking out blue was kept in a jam jar stuck to a pad of plywood, there was probably more blue on the outside than the inside !! As it was open to atmosphere, it was nice and thick and worked really well. I have to say that the last 'bottle' that I bought was a bit thin, so I left the top off for 6 weeks or more for it to thicken up.
I have used ROCOL marking blue in an aerosol can, but found that it needed 3 coats or more to get a half decent result. As others have said, a felt pen works well for smaller parts - saves washing the brush out in meths.

As far as I know micrometer blue is an old style oil paint but may be ground more finely. I'd hazard a guess that it could be made by mixing oil paint with a grease such as vaseline.

A much older alternative that I have used is raddle. The name comes from rouge but it was made by mixing very finely ground red lead oxide with oil. If finely ground rouge is available it might be possible to make some. I doubt if that will be red lead oxide now. Actually raddle is much easier to use than blue. A thicker coating can be applied so there isn't any need to use such a thin coating of blue that it's hard to see it.

The easiest answer to marking out blue is to scribe a heavier line. This might still be a problem for older eyes. If a marker pen is used there is no need to cover everything with it - just where lines need to be scribed. No marking out blue when I did my apprenticeship. Some interesting tasks like filing to a scribed line but only reducing it's size by a factor of 2. Mostly on sheet metal work. It's possible to work to around 0.001in that way. Plenty of raddle as they also owned a battery factory so the lead oxide was easy to get.

John

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Emgee

Have you any evidence that PI causes cancer? if you eat cans of it?

I've spent nearly 40 years in the print industry and never heard of that

Our favourite use for engineers blue was to smear some round the eyepiece of a loupe, and then invite some unsuspecting bod in the workshop to come and admire the finish on something we were working on.

Neither had I (although I have heard that licking your fingers when counting photcopied sheetsis a bad idea because of the carbon black. But Unite says "There is a large body of medical evidence which implicates work in the printing industry with an increased risk of developing Bladder Cancer."

Neil

Rouge is iron oxide, not lead. Still widely availabl in powder form. Don't know how finely it is ground. Also used as a very fine abrasive for polishing.

Hello, I am new member from Sweden. I hope it is ok to post links. How about this product? http://www.mercateo.co.uk/p/2794I-692(2d)362/Starrett_DZ010_Marking_Layout_Ink_Fluid_Tin_118mL_Blue.html

I didn't say it was.

As far as iron oxide goes it's available very finely ground. One of the rock people on ebay has it but seldom sells as it's so messy. 1 or 2 um, maybe less as I can't remember. Hence the raddle I used been based on red led oxide. It's not messy and doesn't stain.

John

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Ian Parkin, pm in your Inbox.

Emgee

If some one wants to try rouge there is plenty on ebay. The seller I bought some off also sold cerium oxide. I asked what the grain size was and also if he had anything finer. If I remember correctly the rouge was 1um. I bought some. Wear rubber gloves if handling it. It's incredibly messy.

There are red versions of cerium oxide available. Grain size of that will be a few um. Lot less messy and might even be suitable mixed in oil.

John

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I think you might be looking for what we call Prussian Blue in North America.

Cheers.

I think it is almost universally known as Prussian Blue, I think it can be got in powder form for mixing with oil etc, used in paint by artists
Ian S C