Frequently Asked Questions about Black-it!

Click on the question to reveal an answer. If you have other questions then please contact us.

Q: How long does a kit last?

Answer: The life of the Blacking solution is directly related to the surface area of metal that has been treated. Something that is often overlooked is a rough surface such as cast iron has a much larger surface area than a similar sized piece of un-machined mild steel. If the Degreaser or Conditioner gets dirty then allow it to stand for a while and then decant off clearer liquid. The Dewatering Oil will slowly get used up.
Note: All of the solutions can be purchased separately.

Q:What is the coverage of the Blacking Solution?

Answer: When processing normal iron and steel we expect the surface coverage to be 3-4 square meteres per litre of solution. Somethings to bear in mind....

  • Blacking box sections and tubes (eg gun barrels) presents twice the surface area (inside & outside). If the inside of the tube is not required to be blacked then we suggest inserting "bungs".
  • Surfaces that have been shot blasted or have a hammered finish also have a greater surface area than a plain flat sheet.

Q: How do I know if the kit is "worn out"

Answer: The Blacking solution will take longer to work until the process stops working altogether. When this happens you should replace the Blacking solution. Do not add fresh Blacking solution to exhausted solution. Also see answer above.

Q: I have just Blacked a part and I had to machine part of it again. Can I Black the whole part again?

Answer: Yes. You can process a part as many times as you like. Once the steel is blacked it will stop working in that area of the part.
NOTE: Before recycling a part through the Black-It process you should make sure you thoroughly degrease it.

Q: I have a long bar to Black. Can I process the bar a section at a time?

Answer: Yes. Since the process will not “over black” then this method produces a finish with no perceptible joins.
NOTE: If you are Blacking a large part in sections then SKIP the Dewatering Oil step until the part is completely Blacked.

Q: I don’t want to black all of my piece of metal; how can I prevent parts of the metal from being blacked?

Answer: Anything that will prevent the steel getting wet will stop it being blacked. Good quality insulation tape has been used to good effect. You can also use nail varnish and remove it afterwards with acetone (or nail varnish remover). Shellac works too (Axminster in UK stock it) and use methylated spirits to remove it. Any paint should work too.
TIP: Since the first process is Alkaline then, depending on your masking material, you might be better applying it directly to the surface to be blacked using a clean rag. After that you can proceed with normal immersion.

Q: What about painting?

Answer: You need to plan ahead a little here. The best approach is to carry out the blacking process but hold off the dewatering oil. Then paint the areas required. After the paint has dried wipe the unapinted surfaces with the Dewatering Oil a couple of times. Leave "wet" for a while and then wipe any excess oil off with the dry rag. As most paints do not adhere to oily surfaces this sequence works well. If you have already carried out the full process, including the dewatering oil, then all is not lost; use the Alkaline Degreaser (or Methylated Spirit or IPA) on the areas to be painted to remove the embedded oil.

Q: What about Zinc or Cadmium Plated parts

Answer: The process needs to react with iron or steel. Plated parts will need to have the coating removed before blacking. You can remove zinc or cadmium coating with muriatic acid (HCl or Hydrochloric Acid). This acid is freely available. The removal of Cadmium is more hazardous and you should carry out the process with care. Removal of cadmium plating by abrasion is not recommended due to the hazardous nature of the dust.

Q: What about Nickel Plated parts

Answer: The process needs to react with iron or steel. Plated parts will need to have the coating removed before blacking. You can remove nickel coating with muriatic acid (HCl or Hydrochloric Acid). This acid is freely available. It is also commonly commerically available as concrete cleaner but check the label to be sure it is an acid.

Q: What about adhesives?

Answer: The answer is really the same as for painting (above) with the addition that some Loctite adhesives are oil tolerant and may not require extra degreasing.

Q: I have a kit for Iron & steel. Will it work on Stainless steel?

Answer: No, the chromium will prevent the process working on all stainless steels.

Q: My kit suddenly stopped working and the Blacking Solution has gone milky.

Answer: The usual cause of this is the steel you are trying to black has been hardened using a cyanide process. You will need to replace the Blacking solution.

Q:I have just tried the kit but it did not work.


When this sort of problem arises we always recommend the following to test the process:

  1. Obtain a small piece, say 25mm sq, of mild steel strip.
  2. Lightly abrade the surface if necessary so that the surface is bright and rust free.
  3. If there is any suspicion of contamination of the Degreaser and Conditioning solutions then do not use them in this test.
  4. A fresh blacking solution bottle should be free of deposits and the solution should be a bright blue colour. Grey deposits usually indicate that something has reacted with the solution and, sometimes, the solution is no longer effective.
    Note: after many successful uses some deposits do form and these can be removed by decanting.
  5. Place metal sample in container of freshly poured blacking solution ideally at 20C or higher.
  6. If the Blacking solution is ok, and the metal is definitely mild steel then, after a couple of minutes, the metal surface will have a dark finish on it.
  7. Leave the metal in the blacking solution for at least five minutes.
  8. Remove metal from solution and rinse with water.
  9. If the metal has blacked correctly then the finish should not come off when rubbed.

If you carry out the above then the results should assist in working out where the problem is.

Please call us directly if the problem persists; we are here to help.

Q: Does the Iron & Steel process work on any other metals?

Answer: There is a small effect on some brasses and white metal but the short answer is no.

Q: Do you have a process for Aluminium?.

Answer: We used to have one but the chemicals involved were not very “user friendly” and we decided not to release in on Health & Safety grounds.

Q: Is the finish Rust-Proof?

Answer: We say that he finish is rust resistant but, as it is slightly porous, the underlying steel can still rust. The secret is the Dewatering Oil which effectively “fills” the pores and prevents any rusting. In external applications we recommend that the blacked item is wiped with a cloth that has been dipped in the Dewatering oil. The excess oil can be wiped off after 10 minutes.

TIP: If the item is hard to reach, or no Dewatering oil is to hand, then WD-40 is quite effective too.