DIY Blue Spotting Blues!

[graham-xrf]

For the metal-scraping folk who would spread stuff on a surface plate..

I have already been the route of using "Micrometer"brand engineer's marking blue, and I didn't like it. For marking, you need to dilute in meths (denatured alcohol), mixed up with some shellac flakes anyway, to give something that will "dry on", and wipes off with alcohol. We all go for Dykem, red or blue, do we not? Colour stuff for transfer when spotting for scraping is different. It must not dry on. It must be spreadable, thinnable, and wipe-off.

For blue (or red) spotting scraped surfaces, either to a surface plate, or reference straight edge, roll it out thin, and go. The Prussian Blue (Ferric Ferrocyanide) mixed with oil is truly mucky stuff that leaves you looking like a Smurf amid a big pile of scrunched-up paper towels! Do NOT get it on your clothes! We get it that this "Turnbull's Blue" is fine insoluble particles, unlike molecular dyes, but it was once used to "dye" the Prussian Army uniforms, so it is quite tenacious!

The answer? Maybe the famed "Canode Blue". It can be had in yellow too, for pre-blue contrast enhancer. As used by our scraping expert teacher Richard.
Very much liked because it washes off with water, non-toxic, etc. HM posts from as far back as 2014 indicate supply is not straightforward!
Unlike from China, imports from USA to UK are awkward and expensive. Nothing found on UK eBay, not Amazon. Not even banggood.com

A part-answer was "Pébéo" brand Oil Colour for Artists in rusty-looking colour "OCRE ROUGE HUILE FINE". A big fat 200g tube for a fraction of the blue stuff price!
It works well too, somewhat friendlier than engineer's blue. Wipes off hands, etc. with alcohol. Even so, it is still colour pigment in oil, though possibly linseed oil - given that it is used by artists.

So I got to thinking.. What makes the non-toxic, water washable, slow drying, re-wettable colour? The only substance I can think of that has these qualities is glycerol (glycerine). The experiment is underway. The intense blue powder used for tracing drain leaks looks for all the world like Prussian Blue, but I am not sure if it is a skin-staining dye, as opposed to a fine particle precipitate, but it is one I will try. I also intend to try known Prussian Blue pigment powder.

Supplies during lockdown shielding self-isolation generally are delivered drop-offs, and I can't just head off to some town to browse an artist's supply store, so we have to improvise, and experiment.

Meantime, if any HM members have some bespoke homespun DIY colour dye-spotting substance recipes, or experiences, I would love to hear about them

 

[derfatdutchman]

Sorry I have not secret spotting compound recipes, always used Permatex Prussian Blue from the auto parts store. I think the tube I have is at least 10 years old or more. The only thing I know that is more messy that Prussian Blue is inletting black used in gun stocking.

 

[markba633csi]

I would think many artist's oil colors in a tube would work, and they are relatively cheap
-Mark

 

[homebrewed]

The intense blue powder used for tracing drain leaks looks for all the world like Prussian Blue, but I am not sure if it is a skin-staining dye, as opposed to a fine particle precipitate, but it is one I will try. I also intend to try known Prussian Blue pigment powder.

The blue drain leak powder probably is methylene blue. It can be found in aquarium shops because it is used to treat fungal infections. It also is used as a redox indicator (as exemplified by a chemical magic trick where a dark blue solution "magically" becomes clear when it is shaken), an antidote for cyanide poisoning and has several other (human) medical applications. It is a dye, not a pigment, so (aside from particulate impurities) there shouldn't be a limit to how thin a layer you can put down.

Mrs Stewart's Bluing appears to be a colloidal form of Prussian Blue so it's not the same thing as drain leak powder. It might be too dilute to work in a DIY spotting compound (but maybe not). This is a brand found in the US, perhaps under a different name elsewhere in the world. Anyway, it would be easier to start with the powdered pigment if you decide on Prussian Blue.

 

[benmychree]

The Canode blue is really the best of all, but when I started scraping, I took a clue from a machine rebuilding book, and used powdered red lead, mixed with lubricating oil to a very stiff consistency and kept in a paper snuff box, which absorbs the excess oil, in use, one drips in a tiny amount of oil and with the fingers rub it around to pick up the lead and spread it around the part being scraped, the same as with Prussian blue. It shows up much better on cast iron than Prussian blue. Yes, it is toxic to a degree, and a bit messy, but not nearly as much as blue.
My daughter, a fine arts printer was able to secure the Canode colors from an artist's supply store.

 

[graham-xrf]

The Canode blue is really the best of all, but when I started scraping, I took a clue from a machine rebuilding book, and used powdered red lead, mixed with lubricating oil to a very stiff consistency and kept in a paper snuff box, which absorbs the excess oil, in use, one drips in a tiny amount of oil and with the fingers rub it around to pick up the lead and spread it around the part being scraped, the same as with Prussian blue. It shows up much better on cast iron than Prussian blue. Yes, it is toxic to a degree, and a bit messy, but not nearly as much as blue.
My daughter, a fine arts printer was able to secure the Canode colors from an artist's supply store.

The Ocre Rouge is more rusty-looking than red lead, and works very much as you describe.

I would be very interested in what the artists dry pigments corresponding to the Canode colours are. Whatever the colours, a main component of what I am trying for is the water-washable fluid. My first try will be something based on glycerol. That stuff is, as it happens, only a short step from various soaps, but I am not aiming for advanced chemistry here.

This is kitchen table style experimentation, except I am already banned from messing with any substances in the kitchen. The ban extends to using any containers except plastic from the trash, and using anything in there that gets hot (oven, gas stove, etc.). The episode of boiling up a carburettor body in detergent water will not be forgotten! I can imagine what would happen if I started mixing up Canode blue me-too in there.

 

[Tim9]

I agree. Lead based white and red leads still have there place. And they are not overly toxic for the occasional use if you are over the age of 30 and past your early development years.
Only problem is finding the white and red leads. And for that... a few years ago I decided to make some white lead. Wasn’t hard. Just a little bit of google led the way. For red lead, one must “toast” their white lead. Still haven’t tried that, but I have my white lead for lubricating dead centers. One doesn’t need much. If I ever get into scraping, I look up the fine details of toasting white lead to make red lead.

 

[graham-xrf]

Tim - drifting off topic on this, but that's OK here.
White lead on dead centers? You wouldn't go to the trouble of using it instead of oil unless it had real advantages!
Does it really work that well?
Also - maybe a brief summary of how you make it?

 

[benmychree]

I think the vehicle used in the Canode colors is an acrylic. If anyone wants white lead, I have lots of it, I have collected it for many years, and I have small paint cans of it for sale for $10 plus shipping; I have poured off the linseed oil that it comes with and mixed in lube oil so that it will not harden on exposure to air. I also have a small amount of red lead powder and litharge (call it yellow lead). Litharge was used before loctite came along to make a hardening cement when mixed with glycerine, it was used as a sealant for oxygen and as a cement of such things as holding thin sleeves in bores.

 

[benmychree]

Tim - drifting off topic on this, but that's OK here.
White lead on dead centers? You wouldn't go to the trouble of using it instead of oil unless it had real advantages!
Does it really work that well?
Also - maybe a brief summary of how you make it?

White lead is an original anti galling extreme pressure lubricant, red lead also works for centers, but I like CMD extreme pressure lube, made of centers and available from McMaster Carr. White lead is especially useful for press fits where galling is always a problem.