# DIY Blue Spotting Blues!



## graham-xrf (Nov 9, 2020)

*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


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## derfatdutchman (Nov 9, 2020)

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.


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## markba633csi (Nov 9, 2020)

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


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## homebrewed (Nov 9, 2020)

graham-xrf said:


> 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.


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## benmychree (Nov 9, 2020)

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.


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## graham-xrf (Nov 9, 2020)

benmychree said:


> 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.


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## Tim9 (Nov 9, 2020)

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.


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## graham-xrf (Nov 9, 2020)

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?


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## benmychree (Nov 9, 2020)

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.


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## benmychree (Nov 9, 2020)

graham-xrf said:


> 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.


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## Tim9 (Nov 9, 2020)

Making Dutch Lead White :: Paintings :: Grosse is a geek
		







						Rare and Hard to Find Art Supplies | Artist Materials Advisor | Natural Pigments | Pigments, Oil Paint, Watercolors, Cold Wax
					

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					www.naturalpigments.com
				




above are just two links I found With google of Dutch Process White Lead.
I can’t find the site I originally used but I didn’t go to the extreme degrees used by Natural Pigments website. No manure used in my kitchen made white lead. I did it about 5 years ago and made a couple pounds of white lead. It’s just not hard to do but takes a couple to 6 months depending on temperature and humidity. And acid used. I used some higher concentration acidic acid. But it isn’t hard to do. Just google Dutch Process White Lead

     And, I think i just mixed my white lead with some way oil to make it a paste. I don’t use it much. Didn’t need it. Just wanted it and was curious about the process.. I think it has more to do with my non-conformist attitude than anything else. I just don’t like when something isn’t available. Want it in case I need it.


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## Mini Cooper S (Nov 9, 2020)

Permatex Prussian Blue! The go to industry standard for scraping. Cheap, designed for the job, and a barrel of fun to put on the bottom of your co-workers toolbox handles! 

Richard


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## eugene13 (Nov 9, 2020)

Mini Cooper S said:


> Permatex Prussian Blue! The go to industry standard for scraping. Cheap, designed for the job, and a barrel of fun to put on the bottom of your co-workers toolbox handles!
> 
> Richard


Telephone earpiece, inside the finger of a misplaced pair of gloves, black toilet seat, let's see how long a list we can compile


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## pontiac428 (Nov 9, 2020)

eugene13 said:


> black toilet seat



That was supposed to be kept between me and my doctor, but it sure explains a thing or two!


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## Janderso (Nov 9, 2020)

I had a very positive experience when I was introduced to hand and power scraping at Richard King's class.
One thing I notice most often when watching a scraping operation on youtube, they have their contrast media too thick.
The transfers are usually smudges. The thinner the better.


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## graham-xrf (Nov 17, 2020)

The first test in the quest for the perfect DIY blue and red spotting fluid has been done. Not yet a resounding success!

The blue was the stuff from eBay used for drain leak reveal testing. The very thing that @homebrewed said was probably methylene blue. It came as a powder in plastic bag within another plastic bag. The stuff is so fine, it handles (in the bag), like a putty, but when transferred to a glass jar, it was powder.

The water-washable fluid I tried was pharmaceutical grade glycerol - or glycerine if you like. Safe enough, tastes slightly sweet, and with a little powder, immediately takes up the fine blue Canode colour. It's not as dark as the true Prussian Blue, but was a good deal cheaper. Mixed with a little methylated alcohol, and with a little shellac, it would very likely make an excellent marking fluid, but we are after the wipe-up-able, water washable, nearly non-drying spotting fluid.

The glycerine does not "spread" and stick as nice as the artists inks, and the grease that is in Permatex. We want something that will stick to the the surfaces better, spread thin, and transfer well.  Glycerine ink can be spread transparently thin, and certainly wipes up easy, and washes away with water, but keeps that "slow runny" character. It is a very pure substance C3H8O3. Just looking at the formula, I can see it has a load of fuel in there, along with some of it's own oxygen, but anyway, test #1 was a bit of a bust!

Maybe something a little thicker. I might try mixing up some blue into baking margarine, or sandwich spread! 

[Edit: Reading Wikipedia, it mentions in UK, a 50mg vial of methylene blue costs about £39.38. I don't think the drain dye can be that!]


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## homebrewed (Nov 17, 2020)

I found an SDS for canode here.  It looks like it contains pthalo blue, not methylene blue.  Also some titanium dioxide (opacifier/scatterer?),  "sulfonated oils", a wetting agent (the "sorbitan monooleate") and an emulsifier (the "nonyl-phenol").

So perhaps the reason canode can be cleaned off with water is because it has some built-in soap?

Regarding the glycerol's poor spreadability in your witch's brew, adding some wetting agent like Tween or Polysorbate-40/60/80 could help there.  And perhaps a film-forming agent like PVA or PVAc would help keep it place better.  PVAc is the primary component of Elmers White Glue, also used in "slime" kits.  You want some kind of non-drying component in there like glycerol to avoid complete drying.  Xanthan gum might be useful here.  Another one is gum arabic, used in a lot of ink formulations.  Or gelatine?  All are water soluble and definitely non toxic.

I suspect the really expensive methylene blue is medical grade.  The stuff does have some medical uses.


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## Richard King 2 (Nov 17, 2020)

In My 55+ years of scraping I have used several blue / black / red/ orange / white  pigments.

My Dad who had been scraping since 1940, used Permatex and red lead as he was introduced to it when he worked for Northern Ordinance in Minneapolis MN.  He apprenticed under German Rebuilders who used them.   Spread with hard white felt, rolled red rag taped with electrical tape, fingers.  We always wiped the bluing and red lead as a final move before rubbing so we knew it was clean.  You feel dirt with fingers and not a rag or air hose blow.

I started to scrape under my dad's supervision in 1964 using a Permatex bluing and making Red Lead as Benchee described.

1960's  Permatex Prussian Blue -review -  greasy and worse one I ever used
             Black soot  mixed with way oil   - greasy but it worked better then Permatex
1960's   Red Lead Powder
1970's   Dykem High Spot Bearing Blue paste - Best of all, but it is hard to remove from hands - Red lead as a high lighter.
1980's   I first used Canode 2243 at General Motors in Indianapolis who helped develop it because of pranks their employees did to each other.  They banned Dykem from their plants.    At first I hated it, but was forced to figure out how to use it and the secret was to roll it on.  I was working for GM full time as a contractor then teaching classes at 9 divions around the USA.  Once I figured out how to use it, I started to spread the word as to how well it cleaned off your hands.  Sold now by DAPRA, Ed Dyjak who I informed.   I have been using it
1980's to 2018  I used Canode Blue,  In the 1990's after using Canode I asked the Mfg. to make the orange color.  At that time they only made Blue, Black, White. Yellow, Red.  The company was sold in the 1990 and at that time they stopped making Orange, Black and White.
I use the Blue as bluing full strength and roll it out with a foam roller, paint brush and hard felt.
1989  -  I started to teach in Taiwan and took Canode with me.  They started to buy 5 gallon pails from me once they used it.  They also use a red bearing blue in Taiwan made in Japan.  Itwoked great, but stained.
2016 -  Am English fellow from Practical Machinist tells me about Stuarts Engineering paste bluing. I bought some from Ebay and tried it.   It was water based and worked OK, but was a bit greasy.  I preffered Canode
2016 - While teaching at Bourn & Koch in Rockford IL, they showed me what they use.   A concrete die powder orange color they mixed like red lead of old.  Also a black carbon powder they mixes like red lead for bluing.  I just wrote them to get the names.  Their plant is shut down /Covid.
2017 -  I started to teach in Germany and took Canode with me to use.
2018  -  Tom Lipton during a Vacaville class introduced me to Charbinel art engraving paint - water based.  (they make a oil base but water based washes off with water.


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## Richard King 2 (Nov 17, 2020)

I saved it and will continue:
2018: I wrote about Charbenel on Practical Machinist and here and people started to use it.   BIAX Germany purchased and had a European (forgot what it's called) approval of import to Europe for Canode.  They bought cases and several gallons of it from me.   They started to sell in Germany
2018 -  Biax sponsored my classes in Germany and Austria and  discovered it you mixed 90% Canode with 10% Charbonel paste Prussian blue and it work great, darker color a lot the dark Dykem of old but it washes off you hands.
2019:   I was walking Thru Walmart arts and crafts dept.  I saw some Ayrcrlic pant selling for $1.00 a tube.  It worked good for as highlighter and not for bluing as it dried to fast.
2019 -  While teaching a class in Austria we tested the Russian ink being sold on Ebay.  It was terrible, worse then Permatex.  We also tested Diament bluing sold in Germany, it worked good, but stained like Dykem,  There was another German Brand I forgot the name and it also stained.
2019 to now.  I use Canode mixed with Charbenel for bluing and Yellow or Red Canode deluted with Windex as a highlighter.   I have some pictures I'll add.


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## Richard King 2 (Nov 17, 2020)

Bluing Pic.  I also started thin spreading the Canode mix with hard roller brayers


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## Richard King 2 (Nov 17, 2020)

Pic of 2009 Taiwanese classes, see Yellow Canoe


			鏟花技藝社群
		

Ink roller bottom picture left:  http://scraping.pmc.org.tw/share.php?display_type=detail&share_id=12


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## benmychree (Nov 17, 2020)

Mini Cooper S said:


> Permatex Prussian Blue! The go to industry standard for scraping. Cheap, designed for the job, and a barrel of fun to put on the bottom of your co-workers toolbox handles!
> 
> Richard


It works well to coat the sweat band of a co worker's hardhat, too!


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## homebrewed (Nov 18, 2020)

benmychree said:


> It works well to coat the sweat band of a co worker's hardhat, too!


Is this the true origin of the moniker "blue collar worker"?


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## benmychree (Nov 18, 2020)

Could be!  The best part was that the guy went to work in the grinding room sharpening pipe facing tools, clamped on his hard hat, noticed nothing unusual, then slipped and ground a divot in a finger, went to first aid sat down for treatment and tool off the hardhat, and the male nurse attendant saw the mess on his forehead and was shocked by what he saw!  OMG, what happened to you?  He was never sure who did it, even though he may have suspected me.  Many years later, at a wedding where his niece was getting married to my nephew, I 'fessed up, and took a hard punch on the shoulder, but it was worth it!   RIP Dick Lenz, fellow apprentice ---


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## graham-xrf (Nov 21, 2020)

Richard King 2 said:


> Bluing Pic.  I also started thin spreading the Canode mix with hard roller brayers


Firstly - thank you Richard for your expansive contribution, and the pictures. Everybody here knows (or has reasonably suspected) that I am an absolute beginner at this art, and I am pleased to be in  a forum where I can so easily get communicating with perhaps one of the most expert and experienced on the planet!

Also to Mark @homebrewed for the (somewhat sneaky) route to the Canode ingredients. I feel should have thought of it too, but I didn't. It shows that using an emulsifier is part of the trick. Of course, emulsifiers is the way most greases end up as water washable. Are not detergents, soaps, washing up liquids, basically emulsifiers? At some stage, emulsified fats and greases have to drop out of the water, making things like the 15 tonne 40m long fatberg in London sewers (2013). I guess my contribution to (old) Hampshire would be stained blue!

*Latest try with "low fat spread"*
Try not to laugh! No tech or clever chemistry involved. So parochial, it was done on the desk right in front of me. In the way of blind experiment. I think it is a concoction of hydrogenated vegetable oils, mixed with culture-grown stuff taken from real butter to give it the flavour, and perhaps a little yellow (ish) food colouring. AKA "I can't tell it's not butter" ???
What it does do is stay as a soft self supporting stuff at room temperature, without melting.

It becomes blue easy enough. It washes away too, though I have yet to let any of this stuff get past the disposable gloves. It also does not work!

I tried it on the scratched side of my 6"dia x 1" optical flat. It can seem to spread, but not easily get that uniform thin layer. When I try putting a V-block down on it, and move it a little, it hangs onto itself better than to the metal, clumps and streaks. Even if just a little _ad-hoc_ experiment, I think we call this one another bust!


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## homebrewed (Nov 21, 2020)

I've used the SDS trick in the past to determine if I could make my own version of something (or to look for nasties I don't want to be exposed to).  Very much in line with my handle .   However some SDS's are more specific than others so it helps if you know a little chemistry.  

Delving a bit more into the SDS for Canode, Googling "sulfonated oil" immediately found a hit:  sulfonated castor oil.  It's supposed to be water soluble --- and apparently fairly safe, since it's used in cosmetics......

And just for Graham:  A UK source.  Amazon sells it, too.


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## graham-xrf (Nov 21, 2020)

homebrewed said:


> And just for Graham:  A UK source.  Amazon sells it, too.


 Hee Hee! Thanks for that.
It says "Sulfonated Turkey Red Oil". Maybe it should go with the red pigment.


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## homebrewed (Nov 22, 2020)

"Turkey red oil."  Once it's spread thin enough for spotting I bet it's pretty much colorless.  For that same reason, I think it likely you will need a fairly high concentration of your blue colorant in order to see it properly.  If it's oil based, maybe the emulsifiers are there to take care of the pigment rather than the sulfonated oil?  Dunno, you'll just have to try it


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## graham-xrf (Nov 23, 2020)

Castor oil, if you look at the chemistry, is a glyceride. It has a glycerol 3-carbons base. The difference is that each carbon can link on a string of fatty acids, but at the root, it is still glycerine, which may be the thing that makes it water soluble. Sulfonated castor oil was, apparently, the first synthetic detergent. Red turkey oil has so many uses, it is widely produced. Thanks for the link. I have some on it's way.

The pthalo-blue is that "brighter" blue as in Canode, and is a common pigment. In paint, for artists and otherwise. Easy enough to get eBay and Amazon hit if it's in a tube with a drying oil (linseed?), which we don't want. Actual powder is not to be seen. I may come across it eventually. I don't really want to have to get at some by washing the oil out of a tubes-worth of artist paint!

[Edit: Strike that - the same place that sells the Red Turkey Oil also has Pthalocyanine Blue Pigment --> *The Soap Kichen* ]


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## homebrewed (Nov 23, 2020)

All edible fat molecules combine a glycerol backbone with fatty acids, so the castor oil isn't the trick -- it's just as immiscible in water as, say, olive oil.  It's the reaction with sulfuric acid that alters its "relationship" with water.

The classic way to make soap is to combine oil with a hot solution of lye, sodium hydroxide (NaOH).  I've made soap this way, just for fun.  The lye reacts with the fatty acids to form a fatty-acid salt and releases the glycerine back into its 3-OH alcohol form. Basically the Na part of lye goes with the fatty acid and the OH part goes with the glycerine.  

Glycerine was an important precursor to making massive amounts of explosives for WW2, and much of that came from making soap. That is why citizens were exhorted to save their used cooking oil for the war effort.


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## hman (Nov 23, 2020)

One of our high school chem lab "experiments" was to make soap the "old fashioned" way.  Wesson oil, lye, and some alcohol to help them mix, boil for a while, then pour it out into a mold.


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## pontiac428 (Nov 23, 2020)

The oils that you are talking about are called triclycerides.  The reaction that @homebrewed described is called saponification (from the greek word Sapphos), where the glycerol is cleaved from the ester linkages of the fats in the presence of strong base.  That's followed by transesterification, where H+ from water caps the fats, creating a fatty acid that has an amphoteric property (one end is liposoluble, the other is water soluble).  The same reaction can also be performed with strong acid.  This is indeed how you make soap and glycerin in the cookpot.  What it all means depends on the result you are trying to attain. Different oils, different catalysts, different temperatures, different endpoints.  Big rabbithole.


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## graham-xrf (Nov 24, 2020)

I kind of guessed from looking at formula C3H8O3 that there was a whole lot of H fuel in there. It's the bones of good ole' "nitro".

I am happy to duck the business of dripping fuming H2SO4 into caster oil. Getting the acid stuff here is a bit fraught also, unless I were to boil up the 2L of battery acid! The UK soap shop to the rescue, and it seems affordable.

Yes - I have wondered what would happen if I just mixed some blue into some soap, but I already guess that that dog likely won't hunt! So far we have ..

1. Sulfonated caster oil (Red Turkey)
2. Ptalocyanine blue pigment
3. Titanium Dioxide Pigment (Chinese White)

The first three we have got some supplies. Then we get to the one's I don't know.

 - - - - - - - - - - - - - -
4. Sorbitan, Monooleate Polyxyetylene Deriv
   It brings up lots of hits on the net. It's a food additive E494. A fatty acid ester.
   Also used for "iron ore flotation" ???
   Allegedly "has a special degree of esterification capable of obviously improving the dispersibility and water solubility of sodium soap" I have no idea what to use here - or to leave it out.

"Suitable for vegetarian" label indicates only vegetable fat used as a source.

*E494 - Sorbitan monooleate:* Produced from sorbitol and lauric acid, a normal fatty acid from vegetable or animal origin. Emulsifier, stabiliser stopping yeast products foaming. Banned in Australia and some other countries. Used in pharmaceuticals.
No idea where one could obtain some.
- - - - - - - - - - -

5. Nonyl Phenol Emulsifier
    Non-ionic surfactant. I dunno. From what it does, it sounds like washing-up liquid, or maybe clothes wash.
    I would be tempted to try Fairy Liquid Wash-up stuff in it's place.

Clearly @pontiac428, @hman  , and @homebrewed managed to stay awake during Chem3.x


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## pontiac428 (Nov 24, 2020)

One thought on the Polysorbate 80 is its purpose as an emulsifier- you could try a small amount of propylene glycol and muddle in some xanthan gum, then mix in your pigment to obtain the texture you want.  This will work and will let you order your supplies from Amazon instead of dealing with any hazmat or proprietaries.


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## homebrewed (Nov 24, 2020)

pontiac428 said:


> The oils that you are talking about are called triclycerides.  The reaction that @homebrewed described is called saponification (from the greek word Sapphos), where the glycerol is cleaved from the ester linkages of the fats in the presence of strong base.  That's followed by transesterification, where H+ from water caps the fats, creating a fatty acid that has an amphoteric property (one end is liposoluble, the other is water soluble).  The same reaction can also be performed with strong acid.  This is indeed how you make soap and glycerin in the cookpot.  What it all means depends on the result you are trying to attain. Different oils, different catalysts, different temperatures, different endpoints.  Big rabbithole.


What he said (much more precisely than I).


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## homebrewed (Nov 24, 2020)

One aspect of the TiO2 component to think about before adding it to your DIY spotting compound.  There are two commonly-available forms that have different crystal structures and very different hardness.  They are the rutile and anatase forms.  Rutile is very hard, anatase is relatively soft.  To avoid potential issues with wear on your granite surface plate, I'd suggest using the anatase form.  Soapgoods used to sell the anatase form but when I checked today, I didn't find any indication of what form they sell (not even in the SDS).  Or you could just try leaving it out and seeing how your spotting compound works without it.

Alternatives to TiO2 could be zinc oxide or barium sulfate.  Both are relatively soft, and, like TiO2, insoluble in water.  Soapgoods sells zinc oxide powder, and your source for sulfonated castor oil probably does, too.

Variations in crystal structure are often associated with variations in hardness.  In addition to diamond vs graphite, boron nitride has two forms.  One is nearly as hard as diamond and the other can be used as a dry lubricant!  Best not to mix the two up, eh?


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## graham-xrf (Nov 24, 2020)

I didn't know about hardness. There are two more, being akaoglite and brookite.
The descriptions of it eBay only sometimes put "(rutile)" in brackets. No other kind is mentioned.
I think if TiO2 in any form is heated up 800°+, it turns into rutile.

The one I got was --> *THIS*
Somewhat cheaper, but actually mentioning rutile was *THIS#2*
The 500g packet came to £7.69, but I wanted in the HDPE bottle with a cap.

I think TiO2 rutile may be  like corundum Al2O3 I guess when it arrives, I try it (as abrasive).
I know it's used along with caster sugar in cake icings, and in paint "brilliant white".

I would have thought that hard abrasive is the last thing we want on our precious granite surface plate. When we do spotting, and that little rub to see the swing point, we would be in effect abrasive lapping.  No wonder toothpaste is such a good metal polish!


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## deakin (Nov 24, 2020)

Richard King 2 said:


> Black soot  mixed with way oil   - greasy but it worked better then Permatex



black soot mixed with linseed oil and a binder. GM formula for older wood truck beds. one of mine is done that way and is still like new 15 years later


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## homebrewed (Nov 25, 2020)

graham-xrf said:


> I didn't know about hardness. There are two more, being akaoglite and brookite.
> The descriptions of it eBay only sometimes put "(rutile)" in brackets. No other kind is mentioned.
> I think if TiO2 in any form is heated up 800°+, it turns into rutile.
> 
> ...


I did say "commonly-available" .

But on the other hand, diamonds fall into that category but aren't commonly affordable!

Going back to Richard's comment and #38 in this thread, If you have a used laser printer cartridge lying around you probably have a small quantity of very fine black pigment to play with.  More "fun" stuff to experiment with.


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## graham-xrf (Nov 25, 2020)

deakin said:


> black soot mixed with linseed oil and a binder. GM formula for older wood truck beds. one of mine is done that way and is still like new 15 years later


Oh yes. Using carbon black did not escape my attention, and used laser printer cartridges can easily be found. Even simply purchasing some carbon black is OK. I did see on YT the technique of two colours, one black, and the other red. I forget which way around, or maybe it doesn't matter, but you get a high contrast set of spots. I think a very thin, near transparent red is put on the scrape metal, and a black on the surface plate, to give black spots on a red background.

This is also done with yellow, and blue. I think that's why Canode, when it could be had, came in those colours.

*eBay mistaike*
Here is one of those eBay mess-ups. I sometimes wonder what would happen if someone tried to pay for obvious mistake. These two items are from the same seller, to whom we award zero points for consistency. It seems 100g of soot costs £6.50 ($8.66).




So - still punting for _"Hobby Machinist Tightwad of the Year"_, I opt to go dumpster-diving for ex-laser printer soot!


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## graham-xrf (Nov 26, 2020)

The Pthalocyanine Blue Pigment + plastic bottle of Sulfonated Caster Oil from the soap-making shop, has arrived. If this works, it will be more blue spotting goo than I ever need in my life!

The passing dark thought is anyone into this soap-making thing, with the essential oils and fragrances and all, adding pthalo-blue from that shop, will definitely end up looking like a smurf!


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## graham-xrf (Nov 26, 2020)

deakin said:


> black soot mixed with linseed oil and a binder. GM formula for older wood truck beds. one of mine is done that way and is still like new 15 years later


If the carbon black worked with the way oil, it might also work with the blue stuff. OK - it still needs spirit or alcohol to wipe away, but this will be something I will try.

I am thinking the spotting goo may not be too much of a big deal. Maybe just about any colour pigment that is fine enough, and is definitely made of particles insoluble in water, can be mixed in with just about any oil that has the right thickness to spread nicely, will do.

With linseed oil, you end up with artist's paint.


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## homebrewed (Nov 26, 2020)

The main thing is that the pigment particles have to be fine enough so they don't interfere with the marking process, and THEY shouldn't be abrasive, either.  I'm thinking about red iron oxide, also known as rouge.

I could be overthinking this.  Old hands at this probably don't worry overmuch about it if they mix up their own spotting compounds.  Richard would be THE source for this kind of knowledge (and I'm glad he's around to help keep our feet on the floor, difficult as that can be at times ).


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## graham-xrf (Nov 26, 2020)

I did mention that my 200ml (that's big) "XL studio" tube of ocre-rouge oil colour for artists, "pebo" brand. It does appear to be red iron oxide. Hmm - a blob of this stuff just might get put under HM-XRF someday .

It was a fraction of the price of a tube of "Micrometer" blue, and it works just the same. It wipes up with spirit or alcohol.
I know I could press on using the various oil-based goops, but I was looking for water washable Canode replacement, reasonably low cost, convenient, and the better if I could hang together a good DIY recipe at home.

I think with what I have, I have probably got all I need. The rest will be a spell of experimentation.


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## graham-xrf (Nov 27, 2020)

homebrewed said:


> The main thing is that the pigment particles have to be fine enough so they don't interfere with the marking process, and THEY shouldn't be abrasive, either.  I'm thinking about red iron oxide, also known as rouge.
> 
> I could be overthinking this.  Old hands at this probably don't worry overmuch about it if they mix up their own spotting compounds.  Richard would be THE source for this kind of knowledge (and I'm glad he's around to help keep our feet on the floor, difficult as that can be at times ).


Maybe not an abrasive problem. The amount taken off in a scrape, even though about half a tenth, or a tenth would take a long time with hard going to be removed by polishing action of rouge. When I ground a telescope mirror, and got down to rouge, it seemed I could go forever without fundamentally changing the dimension. A full polishing with the rouge stage adjusts the surface by less than one or two millionths. It is because rouge cuts so slowly that cerium(IV) oxide is used instead.

The rusty red looking spotting compound we see being used in the videos has a very high probability of being iron oxide.

[EDIT: Just a heads up for anyone who gets around to messing with Pthalo-Blue. If you lose even a some milligrams onto any surface, the effort to clean it up will contaminate you, your disposable gloves, anything you touch, and anything you touch even after the cleanup. It spreads, and spreads, forever. The tips of my fingers are going blue again, maybe from keyboard keys. It does wash off skin with liquid soap and water, but only by getting ever fainter. Final stains can be picked up with plastic eraser. One hopes it sticks to and stays in sulfonated caster oil better than it sticks to most everything else].


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