Introduction: Artificial Metal Pigment for Painting (Second Part).
Instead of focusing on dyes from fruits and vegetables, I am now going to show how to make several dyes (Dipotassium tetra antimony septa sulfide) dihydrate (K2Sb4S7*2H20.), Mars pigment (Iron (II) hydroxide that forms Iron (III) hydroxide, Copper oxide with citric acid, Cobalt carbonate in excess sodium carbonate, etc.
Warning: We are preparing Potassium antimony tartrate about 5 g and adding it while stirring and crystalized out to a Chemical mixture of (Sodium thiosulfate and Tartaric acid) it produces a fair amount of hydrogen sulfide which must be vented outside with fresh air.
Altho they say H2S is equally as toxic as Cyanide gas this is not the case it is second to Carbon monoxide, etc and if done with lots of fresh air and you wear a gas mask then you can work with Hydrogen sulfide (H2S) fairly safely.
Potassium hydroxide is very corrosive, wear PPE. Copper sulfate is toxic and irritating, Iron sulfate is toxic and irritating.
Antimony oxide is a toxic and suspected of causing cancer chemical (wear PPE plus a dust mask when working with this chemical.
Tartaric acid is irritating acid, wear gloves, and PPE.
Hot plate and Magnetic stirrer.
Jewelry Scale 1000g +-0.001 g.
Distillation equipment (Including a 1 L three-necked round or flat-bottom flask, clamps, support stand, distillation condenser, and tubing with Pump.).
Gas adapter, hose, and 250 ml Gas bubbler (designed to prevent suck-back), and neutralize any toxic gases.
Antimony Oxide 99.99 percent Pure.
Tartaric acid 99 percent pure.
Citric acid 100 percent.
Potassium Hydroxide 95 percent Purity.
Potassium bitartrate 100 percent pure.
Sodium thiosulfate 98 percent pure or greater.
Cobalt Sulfate or any cobalt salt (like Cobalt Chloride) -99.99 percent Pure.
Sodium carbonate- 99 percent Purity.
Step 1: Preparing Potassium Antimony Tartrate Crystals in Solution and Prep of K2Sb4S7.
We weigh Out 11 g of Antimony oxide (Sb2O3) and add 5 g of Potassium bitartrate with Hot water into a 1 L round or flat-bottom three-necked flask. We seal the joints with rubber stoppers and add a stir bar. We then set up for reflux with a hotplate at 170 degrees and near 90-100 while stirring.
Note a thick impartial mixture of the Antimony oxide and Potassium antimony tartrate (excess) may interfere with reflux requiring temps near 230 to 240 degrees C for the hot plate and the flask will need medium stirring 350-400 RPM.
Let it run and check on the temp with a good digital thermometer and probe that you can buy on Amazon for 50 dollars it more accurate than a meat thermometer. Let it run for 4-5 hrs and then turn off stirring and heat and unplug the pump that provides cooling to the solution.
You may need to set up with a 6-inch steel rod and clamp and stand the Gas bubbler (Scrubber). Then you put a rubber hose to the joint of the gas after which is glass (24/40 joint).
Add 200 ml of water plus 30 ml of cabbage extract (Aqueous) and then carefully with a funnel add 5 g of Potassium hydroxide. A glass stir rod (Clean) should be used to stir the Cabbage extract and Lye. This acts as a scrubber for Prep of K2Sb4S7 in case any excess H2S (Hydrogen sulfide) is produced. The lye will create if any Hydrogen sulfide is present sodium sulfide. This is a very important step.
Decant the finished product there will be excess Antimony oxide in it but you want a clear solution with no white powder (as little as possible). I had 250 ml from 500 ml (50 percent loss) most of that was a white sludge. It must be done Hot so wear gloves that can resist Heat (Heat resistant gloves) for this.
Preparing the situ of Hydrogen sulfide. I wore a gas mask and I made a solution of 250 ml of water kept in the fridge at 4 degrees C (this will produce less H2S). I weigh out 20 g of Tartaric acid and add it to the bottle and shake it. Then I add 8 g of Sodium thiosulfate. The ratio of Tartaric acid must be at least (15 g acid for 5 g sodium thiosulfate).
Shake and go outside with a mask to vent the toxic H2S.
Set up for distillation with the 200 ml (2-3 g of Potassium antimony tartrate at heat to about 50 degrees C the solution. With a glass funnel clean we add the (Tartaric acid and Sodium thiosulfate mix). The solution should with good stirring go yellow, light orange to Orange.
Note make sure the temp stays below 60-70 degrees C. If allowed to boil the acid could react leading to a massive release of Hydrogen sulfide you DO NOT WANT THIS. It is important that the mixture does not reach near boiling temps. Also, your dye could turn black the breakdown of antimony dye in the process.
Not shown well but I use the bubbler to scrub any H2S but it seems like that not needed at 45-60 degrees C no bubbles passed into the scrubber.
Step 2: Copper Oxide Pigment Preparation.
To make the copper oxide printer-like tone we add 19-20 g of Potassium hydroxide flakes to a 600 ml flask and then we add 25 g of copper sulfate. We quickly add the water 500 ml and stir by spoon. It will get hot and release some steam and it should turn black-brown.
We place the mixture with a stir bar at medium speed for 1 hr. Then you have the crude pigment that must be treated with a weak acid.
You now have the copper oxide but the excess lye makes the pH around 14 and this will attack any cellulose in the paper thus degrading it. We need to add a weak acid (Citric acid or Tartaric acid).
We fill the solution with (full PPE) into a flask 1 L or bottle with a cap. We slowly add 1-5 g of citric acid and mix the solution capped then we use a large Pipette 10 ml to place into a small 50 ml beaker and we test the ph. It took 16 g of citric acid to change the ph to 6.0!
The copper oxide due to the acid (citric or tartaric acid) will produce a blue to blue-green hue over the copper oxide pigment. Here a video on how to make the Oxide of copper.
Step 3: Making Mars Pigment (Iron(II) Hydroxide).
For the Mars Pigment we put in 20 g of Iron Sulfate into 500 ml of water then add slowly 20 g of Potassium hydroxide this forms Iron (II) hydroxide. It must be quickly stored in a glass bottle since the plastic types will not tolerate the concentration of lye here. Also it must be air tight too.
When exposed to air with paper the sludge of Iron (II) hydroxide forms Iron (III) hydroxide. Here a video on Mars Pigment.
Pipetting the iron hydroxide can have very interesting results.
Step 4: Cobalt Carbonate From Cobalt Sulfate and Sodium Carbonate.
We weigh out 20 g of cobalt sulfate and add slowly to 400 ml of water about 25 g of Potassium or Sodium carbonate fizzing will result so be careful. A beautiful Purple pigment will occur after mixing.
On paper, it looks like a purple stain. If you use K2Sb4S7 2H20 crystals it will give a glossy purple color. It not known why this happens or with the other Pigments but it may be the Tartaric acid and remaining K2Sb4S7 2H20 crystals.
Step 5: Conclusions for This Artificial Metal Dye Project.
Antimony metal pigments are very interesting to work with but the production of Hydrogen sulfide is not and you must have pre-cautions like a gas mask and keeping the water at 4 degrees before mixing and then storing outside.
A good thermometer that can go to 0 to 500 degrees C is required altho I would never go past 120 degrees C. The probe wires sensors can only go max to 330 degrees C before destroying themselves.
A good hotplate and magnetic stirrer are required.
For bigger scaled-up production of K2Sb4S7*2H20 I recommend two gas glass scrubbers with Lye.
The metal art painting is very interesting with cobalt salts, iron pigments (Iron (II) hydroxide), copper oxide pigment, etc.
Thank you for reading this Instructable.
2 years ago
I just made Copper ferrocyanide pigment Cu2Fe(CN)6 H20 by adding 8.64 g Potassium ferrocyanide and 10.42 g of copper sulfate to 200 ml of tap water. Mix the Potassium ferrocyanide with hot water first allow it to cool to room temp and add the copper sulfate it will get a bit warm.