Every time I use a chemical blackener (usually on brass) it ends up a mess. Instead of the metal itself turning black, it just creates a thin, fragile coating that comes off with the slightest touch, showing bright metal underneath. What the heck is the deal??
Also, it's very difficult to get glue or paint to stick after this treatment, despite wiping off the black gunk.
Hi Ray,
I use my sand in front of the blacking-ray system with grain Aluminiumoxyid 180th
Only when the metal is ansolut pure, it can be burnished to abrasion.
Quote from: Ray Dunakin on October 10, 2011, 04:09:18 PM
Every time I use a chemical blackener (usually on brass) it ends up a mess. Instead of the metal itself turning black, it just creates a thin, fragile coating that comes off with the slightest touch, showing bright metal underneath. What the heck is the deal??
Also, it's very difficult to get glue or paint to stick after this treatment, despite wiping off the black gunk.
My advice is the following:
1. The brass must be squeky clean. Some form of absasive cleaning must be used. Grit blaster, steel wool, fine emery cloth, etc.
2. Dillute the blackening solution with distilled water. I have used 1 part of blackening to 5 parts of water
3. Do not dunk the part in the chemicals.
4. Apply the chemicals with a small paintbrush or cotton swab
5. Keep brushing the solution around, keep it moving, add more.
This takes time! At first nothing seems to happen, but slowly the metal starts to blacken. My experience is that this way you can get a finish with absolutely no crud. My theory is that when you dunk the part and/or the solution is too strong, a layer of crud is immidiately formed, and blocks any further blackening.
The best blackening in my experience is Birchwood Casey Brass black. Their Aluminum blackening works on brass as well.
By the way, If your brass is meant to look like steel, it can be polished after blackening with great results.
Last: Wear gloves! You will be handeling the chemical infested part quite a lot, and you will absorb the nastu substances through your skin without gloves. Rinse the parts thorougly with water. Micro Engineering say that you can use white vinagear as a neutralizer for their blackening solution, but I cant really see how you can neutralize acid with acid...
Regards, Haavard H
Havard's advice is sound and reflects the best information I have read. Copy it and follow it to the letter. -- Russ
I have a stock of all kinds of patinas. I have found that using ones marked for specific metals actually may work on other metals. Birchwood Casey gun blue for instance works on other metals than ferrous varieties. I was particularly annoyed by attempts to darken brass for ship models as the surface flaked on my work also. Recently I discovered that JAX Chemical Co., whose other patinas I have found to be quite effective, has a brass browning solution that was just right. It turns most metals based on copper a dark brown that does not rub off but can be polished to bring out highlights. Here's a link......
http://www.jaxchemicals.com/jaxshop/shopexd.asp?id=37
Ray
Check Wikipedia for the following info: Under the heading of "Liver of Sulfur" It lists a variety of names other than the following chemical "LIVER OF SULFUR" unfortunately unable to locate a source in liquid bulk form which I believe would be a lot cheaper than purchasing a small amount in say a Michaels or Micro Mark or Birchwood Casey or other specialty store's, maybe you might have better luck where your located.
Wikipedia lists the following: it's other names, pro's and con's and mediacl uses.
I purchased Birchwood Casey gun black from my local gun shop and also consider it the best product, as for whats available on the market
I have seen this liquid turn copper black.
People who work with stained glass have also utilised this material to turn both Brass and Silver black.
Good luck
Henry