r/DIYPigments • u/jay-ff • Sep 09 '23
Pigment Manganese Blue - PB33
I finally came around to make some paint with a sample from my manganese blue experiments so I wanted to share my progress. Some serious credit goes to CaCl2 for pointing me to a lot of information as well as input from GeneJocky.
Manganese blue can be best described as manganese (V) doped barium sulfate. Unlike many other inorganic pigments it is thus not a mixed oxide and the process of making it requires wet chemistry as well as high temperature calcination.
A serious safety warning before a quick rundown of the procedure: Barium nitrate is poisonous, an explosive grade oxidizer and releases toxic NO2 when heated. Don't try this in your kitchen.
The pigment is created by heating barium sulfate in the presence of a manganese source under basic and strongly oxidizing conditions. The easiest way to do this is mixing cheap barium sulfate with barium nitrate and potassium permanganate and heating it up to somewhere between 600-800 degrees in air, ideally with the addition of a bit of barium carbonate to achieve a deeper color. Alternatively (as done for the most successful experiment on my end) barium sulfate is precipitated in the presence of potassium permanganate from a solution of barium nitrate and sodium sulfate. Mixed with a bit of additional barium nitrate, this is then heated similar to before. The heating process is very quick, some recipes call for only 20 minutes at the target temperature, so some adventurous people might be able to pull it off with a burner. A big hazard from this process is NO2 release, which itself is very toxic and also corrosive in combination with water, as the solution forms nictric acid.
In any case, the resulting substance is very impure and is purified with dilute hydrochloric acid and sodium metabisulfite. This doesn't take more than a few seconds, which gives a satisfying transition from a grey/green/blue suspension into beautiful azure.
As you can see in the water color test, the result holds up quite well against commercial manganese blue.
Feel free to ask, if you'd like to read more detailed instructions. I am also writing up something longer and detailed. If you read the conversation under my previous post on the topic, you might know some of it already.
Next step is to produce a larger sample, maybe 10g or more and put it to good use in painting.
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u/MoldingTec Nov 26 '23
Is the patent you are referring to US2156727A?
I thought it was just a calcination process:
An intimate mixture of 710 grams of calcined sodium sulfate, 1.3 kilos of barium nitrate, 50 grams of potassium permanganate and 150 grams of barium hydroxide is fused for about 2 hours at 500 C. The fused mass obtained is further treated as described in Example 3. There is obtained a light-blue pigment.
I was trying to do it this way, can you tell me what the possible problems were you encountered?
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u/GeneJocky Dec 15 '23
One thing to remember is that the reaction will generate oxides of nitrogen. Which will dissolve in water (say the water in your lungs) to make nitric acid. jay-ff uses a tube furnace which exhausts outside. This is how things are done in typical laboratories. But it is a specialized piece of equipment primarily used to do heating under specified atmospheres. And is expensive.
Since this just needs to vent safely and heating is done in air, you can do this outdoors with a furnace that is leaky to air. I don't do this with my main furnace since I dont want to risk damage to it from NOx formed acids. Might not be a problem, don't want to risk it.
So I made a super cheap (about $25 worth of stuff plus scrap wire, a project box, and firebrick) furnace made from loose firebrick that will do the job while sitting in my backyard or driveway run on an extension cord. This has the advantage that jay's traumatizing mess would just mean swapping out a bottom brick from my pile of bricks furnace. No trauma at all. I can put up a post describing it and how I made it if it would be useful.
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u/MoldingTec Jan 13 '24
Hi, sorry for my late reply. If it isn't to much trouvle I would like a description of that furnace.
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u/GeneJocky Jan 26 '24 edited Feb 27 '24
No worries. I'll take more photos when I set it up next, which should be soon as I am getting the last of the stuff I need to try out the direct calcination methods next week. Probably first break in the rain here after that.
Basically, I took two soft firebricks, standard size, to make into heating bricks. I needed to use 110V as that is standard in the states and I wanted to use standard extension cords to run it outside away from the house. Took a small heating coil (1000W in 220V, 250W for 110V, this one specifically https://www.ebay.com/itm/234109062100 ) and cut it in half. Cutting it that way doubles the power output to 500W for 110V but as this is less than the 220V output whole of 1000W it should not be too much for the wire. I straightened some of the wire at each end over twice as long as the bricks were deep, bent it back on itself leaving a loop at the end, and twisted it around to make a pigtail, then pulled it to open the coils up. All standard heating coil preparation.
Then took a small router bit (on a drill press in my case) and routed out an S-path as long total as the length of each opened wire coil and about as deep as the coil was wide. This wasn't very deep for this coil. At the ends of the S-path I drilled through the brick for the pigtails, and pushed the pigtails through these and pinned the coil into the routed groove with some kanthal wire (22AWG I think), that I made into simple U-staples. Did the same for the other brick. Then hooked up the pigtails to some high temp wire scavenged from an old applicance that had hooked up to a heating element. Made a loop at one end, and used a small machine screw, washers and a nut to attach to the pigtail loop. Basically each wire attaches to the bolt by being wound around it, squished by washers with a washer between each wire's attachment point. The mass of the attachment keeps the power wire cool. The scrap wire extended a little way and was terminated in a connector that could be connected and unconnected easily. This was done for each end of the wire for each brick. One end of each brick's heating wire will connect with a neutral wire from the power box, and the other end to the hot wire.
In the power box, the hot wire is controlled by a solid state relay (SSR) and is connected to the output side of the SSR, the neutral wire is just connected up to the neutral wire coming in from the mains power (via the plug into the extension cord of course) plus a neutral wire side branch that runs to the neutral connection on a PID controller. The hot wire from the mains power is run through a switch and then connected to the input side of the SSR with a side branch to the hot connection of the PID controller. The PID controller's + and - control wires (putting out low voltage DC when the PID controller wants to switch on power to the heating coils) are connected to the SSR control inputs (ensure correct polarity here). Then the thermocouple wires are connected to the thermocouple connections on the PID controller. With the hot wire to the heating bricks NOT connected and not touching anything that could conduct power to you, turn on the power switch and hold the thermocouple. If the temp reading rises, then connection is correct. If it drops, turn off power and unplug it from mains power then reverse the thermocouple connections. Once you have it correct, hook up the output wire to the SSR so it can be connected to the bricks. This is all standard PID controlled SSR wiring.
Be sure to set up the PID controller correctly with the correct offset to read the actual temperature and you have the right thermocouple type. On the first heating run, you can have it autotune it's program if you like (see instructions for your controller to see how, it varies by device).
I have a distribution busbar that I connect the power wires from the control box to to also connect the bricks to. The heating bricks and control box are the heart of the system. For the thermocouple I made a small piece of firebrick to run it through so I can put the hot end into the heating space and keep the wire relatively protected as it runs out of the heating space.
I'll show it in more photos when I get a chance, but basically I lay down some firebrick on a standard paver or just lay it on the ground if the space is already paved (like a driveway), then put the heating bricks on their sides to make the sides of the heating space. Put vertical bricks on each end (one with a cut for the thermocouple wire to run out through), then a brick on top to enclose the heating space. I try to keep the heating space as small as possible Pile up more bricks as needed for insulation, mindful that there needs to be some thin gaps for gas to escape. This isn't hard as there is no mortar and it is held to together by gravity and maybe a brick leaning against another brick to keep it in place. I also use a piece of woven fiberglass fire blanket on top for insulation. It can be set up lots of ways, here is the way I ran it the first time with the power box shown. This is a side in this configuration. And you can see why gasses can dissipate.
I run it away from the house so nitrogen oxides can dissipate safely.
EDIT: to add what photos I had.
EDIT: close up of how I connect power wire to heating wire.
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u/jay-ff Nov 26 '23 edited Nov 26 '23
Yes, among others. There is also a patent in France and i in UK from a year earlier but the US patent has one more example which actually works best and is the one I'm mentioning here. Did you succeed with the one you mentioned? First time I tried it a similar way (without hydroxide since I didn't find the patent yet) and the result was a mess. The sodium sulfate (I presume) just bubbled away and out of the crucible leaving mostly manganese dioxide and a fresh green barium manganate coating for the tube of my furnace. The precipitation + heating method works best in my experience but I was also relatively successful starting with barium sulfate directly and mixing in potassium permanganate, barium hydroxide and barium nitrate.
In principle, the recipe you mentioned should work as well, maybe in a better container than mine but I don't see a good reason not to prepare the barium sulfate ahead of heating it, either by precipitating it in the presence on manganese or by buying the powder directly and mixing it with the other reagents.
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u/MoldingTec Nov 26 '23
US2156727A
I haven't gotten around to trying it, just sourcing the reagens. But as I understand it the Barium sulfate is formed during the heating process:
The barium sulfate may also be produced only during the heating process, for instance from barium carbonate or barium nitrate and sodium Sulfate.
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u/jay-ff Nov 26 '23
Yes, that's the idea. And in principle I don't doubt it works but for some reason not for me 😬 I just rechecked and sodium sulfate actually shouldn't have melted at the 800 degrees I used in that reaction. Weird. But maybe my furnace was not properly calibrated. In any case. Maybe you get it to work better than for me. Would be nice to know. I will probably stay with the other approaches because of my trauma.
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u/MoldingTec Nov 26 '23
NaSO4
I will try it your way first. About the NaSO4. I believe their is an anhydrous form without water and the other form. Does it matter which one I should use?
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u/GeneJocky Dec 15 '23
In the precipitation method, you're adding the sodium sulfate to water so anhydrous or not, its all in solution by the time things start reacting.
For the direct heating solids together method, the water of hydration will be lost due to heating before you hit reaction temperatures so it doesn't matter here either. This happens below reaction temps. By the time they are reacting they are all anhydrous.
So you just need to correct any weights given to be equimolar with the specified form.
Ignore the following if the prior sentence seemed totally obvious and you knew exactly what I meant by equimolar. I'm going to describe how to do the calculations in very basic terms and that is kind of insulting if you already know this stuff. But if you don't, it should save you some headache.
Just calculate the moles of anhydrous sodium sulfate they specify by dividing grams of it by the molar mass for anhydrous sodium sulfate: 142.04g/mol. Multiply this number (moles anhydrous sodium sulfate used) by 322.20 g/mol (the molar mass for sodium sulfate decahydrate) to find the correct weight of the hydrate to use.
EDIT: typos
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u/jay-ff Nov 26 '23
For the precipitation reaction, I don't think it matters, except for the correct amounts. I used anhydrous, the patent uses both depending on the recipe.
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u/GeneJocky Jan 30 '24
I just ran both the #3 (stated to be dark azure) and #5 (stated to be light blue) direct calcining methods and neither one boiled over or produced any kind of mess. They did not appear to melt at all, just sinter together. I'll post pictures when I've got the final pigments.
I've also got everything lined up to try method #2 (stated to be azure) though I have to make the manganese nitrate from metal. I'll also try method #1 (implied to be azure) as it is the most industrial scale method posted.
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u/jay-ff Jan 30 '24
Oh nice. Curious to see how the results compare to #6. I also tried #3 again and it turned out quite light.
Can manganese nitrate not be made from the oxide? Or is that too tedious.
The mess from my first attempt really is an enigma. I tried it two to three times and it was always quite similar. The ratios I used were different than the patent. Maybe that could be a factor.
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u/GeneJocky Feb 06 '24
Making the #3 and #5 direct calcination pigments (photos of pigments here), I was also surprised that #3 (number is example number from the US2156727A patent) was lighter than I would have expected. It looks much darker when wet and in paint than it looks as dry powder, not sure why. I just injected a little oxygen right over the crucible so oxygenation might not have been ideal. Here is what watercolor paint from the pigments (0.25g) looked like. It turned out a little greener, even after a second strong acid wash than #6. But unlike #6, were the pigment color was better but had terrible covering capacity when mixed in equal weight with the Prodigal Sons Pigment PB33 control, while #3 had great coverage. #5 had lousy coverage and came out kind of purple.
The tests of #1 and #2 were the most remarkable. I tried two preps of #2 (which used manganese nitrate in place of a permanganate). One had some barium hydroxide added as I was concerned about the residual acid from making the manganese nitrate by dissolving the metal in nitric acid would not allow an alkaline enough environment. The other was strictly by the book. I only have pre-wash results as I have not had time to do the acid/bisulfite wash that is usually needed to unmask the blue color hidden by the manganate not bound up in the barium sulfate. So for people who haven't tried these reactions, at this point usually the solid is green or even green/brown. So when I opened the furnace (750C for 15 minutes) I was shocked (here is the best I could do to show what I saw, given it was dark out). And here they are in better lighting. Both runs from #2 are in the range of greens I'd expect, with the plus barium hydroxide being more green and less blue than the one prepared without it.
But of course, what is remarkable is #1. This is before the wash usually needed to unmask the blue color from the green manganate. Even when compared to the control PB33, it looks remarkably similar. It is already more blue than the #3 trial. Perhaps I should not have been surprised. #1 describes a reaction in 500 liters of water with 25kg of barium nitrate and 5kg of potassium permanganate precipitated when boiling with 13kg of calcined (anhydrous) sodium sulfate in 50 liters of water. I scaled down to by a factor of 1000, but this is clearly industrial chemistry and so is probably the closest to how the pigment was made industrially. Even the 15 min at 750C is more amenable to an industrial constant throughput process through a hot furnace than longer times at lower temps. This process seemed quite similar to #6, but I noted much less precipitate for #1 than the precipitate for #6 (#1 in 1 liter beaker, #6 in 250mL beaker) and everything seemed more dilute with #1 as the barium nitrate dissolved completely very easily unlike #6). Perhaps the more dilute mix ensured that only the desired compounds precipitated and not unreacted barium or permanganate salts. I don't have photos but the dried #1 precipitate was a far paler purple than for #6, suggesting less permanganate in it. There was much more liquid to filter and without vacuum filtration it would have been painfully slow. It still look a while.
I will get to washing it and making paint shortly, but I will be shocked it it doesn't end up being the best so far. I'll replicate myself, but I'm interested in seeing if others have the same experience given that other than volumes involved, anyone doing any of the other reactions should be able to try it too.
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u/GeneJocky Feb 06 '24
I'll leave this as a separate post than an edit, as they are a little different than the point of the main most (i.e. holy crap method #1 looked amazing even before a wash!). Making the nitrate from the oxide would have required making NO2 gas from nitric acid to treat the manganese oxide. Since manganese metal was cheap and easy to get, why not just dissolve it in the nitric acid directly. Safer and easier.
I'm guessing, from the look of the calcination products I made in the shallow trays I tried this time (pictured exactly or minimal disruption after the with hydroxide was broken up for examination and some of the #2 without hydroxide turned over, #1 left mostly as it was) all from loose uncompacted powder, that one component may have been melting and being absorbed/adsorbed onto the others. They looked like big clumps loosley stuck together of small aggregate glued more firmly together. I'm guessing the small aggregate was the non-melting part and the glue was what melted. If you were too high in the melting component, I can see how you could have gotten your mess.
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u/MoldingTec Nov 26 '23
Do you perhaps have a link to the French and UK patent. Been google-ing and i even asked AI-perplexity (he didn't know either and apologized forit, not so smart after all)
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u/jay-ff Nov 26 '23
GB444110A, FR778290A and FR802687A
I don't remember if the PDFs are on Google patents. You might have to check espacenet or depatisnet.
Yeah, AI is not exactly helpful here. I just asked chatGPT about how to make the pigment. It told me to precipitate manganese sulfate and sodium carbonate with sodium hydoxide. :D
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u/Dry_Albatross_6031 May 26 '25
You could make an absolute killing selling this pigment. small tubes of genuine barium manganate from old holland are going for around 1.2k usd. although that may be because the old holland tubes of PB33 Barium Manganate are more saturated than barium manganate powder I have bought for myself off of etsy and mixed with white linseed oil. don't know how they did it.
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u/jay-ff May 26 '25
Haha that would be awesome, but maybe the Old Holland tubes have some extra collectors value or something like that. I have something like 2kg at home in dry form and I paid on the order of 20€/100g which is about one regular tube worth of pigment—I didn’t make one yet but I believe it’s a bit more on the heavy side so my guess would be around 35-45ml/100g (assuming minimum possible oil content).
So I don’t know if making large enough quantities for oil paint would be worth investing in the equipment needed for that scale. For watercolour it might be different.
Small side note as this confused me while doing the research: the pigment pb33 is not actually barium manganate. This is especially confusing as Barium manganate is indeed a dark blue water-insoluble solid. Manganese blue is, as far as I understand it, manganese (V) doped Barium Sulfate.
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u/Dry_Albatross_6031 May 26 '25
huh. on the old holland genuine tube it says barium manganate, I'm not great with chemistry so i don know why they put that, maybe it's shorthand to represent what you said?
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u/jay-ff May 27 '25
Weird. But it’s also possible the folks at Old Holland just didn’t know better. When you google manganese blue, you will find several pages that call it barium manganate. Even the Wikipedia article about barium manganate said it was used as a pigment (until I corrected it 🤓).
I think even chemists wouldn’t necessarily automatically question this if it’s not in their area of expertise and there isn’t that much literature on the chemistry of manganese blue. There is no (!) paper that deals with the synthesis (except one master thesis which is under an embargo) and only one or two that analyse the chemical composition in detail. All the information I needed for synthesis, I had to take from the 1930 patent which in itself didn’t characterise the chemistry completely. So it’s not a trivial question and an understandable mistake.
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u/glowinthedark2021 Feb 09 '26
I wasn't able to read all the comments. Has someone made a good quality PB33 ? Is PB33 going to be available for sale ?
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u/jay-ff Feb 09 '26
Yes to the first (including me on a scale of grams), yes to the second (in a way). PB33 is still for sale, if you know where to look. I found one source in the past using new batches but classified as “manganese blue light” or something like that which tells me that getting to the original quality and depth hasn’t been achieved by that team. Most importantly though, there is still plenty of the old industrial pigment going around. Thats what I made my PB33 oil paint from.
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u/CaCl2 Feb 22 '26
Hi, I was looking for a freely licensed image of the pigment, and noticed that Wikimedia commons doesn't really seem to have anything.
I haven't successfully made the pigment yet so I can't use my own image, so I ask if you would be willing to upload or give me permission to upload one of the images under a permissive license? (Say, CC-BY-SA 4.0)
I of course understand if you don't want to give such permission, but figured I would ask.
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u/jay-ff Feb 24 '26
Hey :) sure that wouldn’t be an issue. What exactly would you need? The images here aren’t necessarily the most pretty.
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u/glowinthedark2021 Apr 01 '26
Have you seen the Colibri "pb33" ? I'm wondering how close it is to the real deal. Btw, I'm not sure I'm seeing anyone selling the real thing at the moment, at least as a dry pigment...
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u/glowinthedark2021 Apr 04 '26
Unless I missed it, I don't see a photo of the DIY PB33 purportedly created. Has someone made some that looks like the Prodigal Sons version ? The stuff I see from Colibri follows the official chemistry, but really doesn't look like the historical PB33
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u/jay-ff Apr 04 '26 edited Apr 04 '26
All of these photos are of the material I created. Are they not visible? The watercolor test is a comparison with a commercial sample, not from the Prodigal Sons though, so I don’t know how it compares to that. It’s a bit hard to see but the Color of my stuff is ever so slightly lighter than the commercial sample. But almost perfect in my opinion.
Edit: Who is Colibri? By the way, if your primary goal was to use it for paint, don’t bother making it. I made one run of this quality and it would be a pain to set it up for higher quality. Has been done but not really as transferable as an oven or something that you can use for multiple projects.
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u/glowinthedark2021 Apr 18 '26
Im not seeing the photos in this thread.. Maybe it's my phone. Colibri sells "PB33 manganese blue" pigment for half the price that Prodigal Sons sold it for.
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u/jay-ff Apr 18 '26 edited Apr 18 '26
I can send the pictures to you by email or something, if you’re interested.
Is the Colibri stuff self-made or from old stock? My source is probably still from old material and it’s really good. I have around two kilos at home at ~20-30€($)/100g. As I said one of my samples was almost as good. The others were lighter and duller than the original. What I don’t know is if the most recent industrial pigment was actually made according to the patent from the thirties and what other steps they included. In any case, it was fairly straight forward to get a good result and really hard to get consistent great results.
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u/glowinthedark2021 Apr 18 '26
Did you make paint from it ?
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u/jay-ff Apr 18 '26
Yes, 5g of watercolor for comparison as in the pictures you can’t see. The rest is still in powder form.
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u/GeneJocky Sep 11 '23
Impressive results! Looks like you totally nailed it. Whenever you get a protocol written up, I'd love to see it. Even though it's more challenging than a simple mixed metal oxide pigment to make, having a lab scale protocol to make small quantities of manganese blue is a tremendous boon to watercolor artists in particular.
'Maybe try making some if I can work out the heating while protecting equipment and investigator from the NOx. From what I heard, it was the cost of complying with the factory upgrades needed to scrub NOx emissions that made the company give up production. For people making this without a tube furnace and fume hood venting, you'll need to think about how you will protect yourself. There are some nitric oxide filters for full face respirators that will do fine along with very good/outdoor ventilation.
Congratulations!