I decided to color in the heel stamp on one of my LRB M14SA receivers today and thought I'd share the process with the forum. Step ONE - Items Required
Gather the proper items you'll need to do the job correctly (in no particular order):
1. Non-acetone based nail polish remover
2. 70% Isopropyl alcohol
3. Gun Scrubber
5. Desired color(s) nail polish
6. Item to be colored
7. Machine oil (pictured later in post)
8. Blow dryer (not pictured)
9. Paper towels Step TWO - Solvent Application
Clean the area(s) where coloring is to be applied. I used Gun Scrubber first because it has the aerosol power to blast out contaminants then leave the area stripped of oils, greases, and grime.
Next, I applied a generous amount of isopropyl alcohol to fully degrease the area. While acetone can be used for the same purpose, this technique is good for all finishes, not just military strength finishes (i.e. parkerizing or manganese phosphate finish). Be cautious that some finishes will dissolve when acetone is applied.
Gun Scrubber -
Isopropyl Alcohol - Step THREE - Heat Treatment
I used a hair dryer on high to blast out any particulates that may be a result of the chemical breakdown of the oils, greases, and grime during the solvent phase. I find that a generous amount of heat will make for a more uniform filling of the stampings that are to be colored in. Step FOUR - Initial Color Application
After you are certain the area(s) to be colored are completely dry and void of contaminants, you can begin to apply the initial coloring. This is going to be one of at least two coats. Probably three or even four coats depending on how deep your stampings are.
When applying the color, I find that it's best to dab the area generously and don't be afraid to really lay it on. The area should be completely covered to the point where the stamping is not readable. You need to ensure that as much coloring as possible sinks into the stamping.
After the coloring has been generously applied, wait just a minute at most. Remember from STEP THREE that you applied heat, and that your receiver (in this case) will be warm or even moderately hot to the touch. The coloring will dry extremely fast.
Use a small piece of white paper towel (cheaper the better; not too absorbent) and dab it in the non-acetone nail polish remover. Wipe affected area just ONCE and throw the used paper towel away.
If you use the same piece of paper towel over and over you will just make a mess and it will make more work for you. Here is what the heel stamp should look like after the first application (notice the smearing): Step FIVE - Follow-up Color Application(s)
Repeat the color application process as needed. Depending on what you are coloring in, you may need anywhere from one to three, four, or more color applications to get the desired results. In this case, I only needed two. Here is the heel stamp and side (foundry stamp) of my LRB M14SA receiver:
While the primary item used to clean up the colored area(s) should be paper towels, you will need to use the Q-tips to "detail" the area and clean it more evenly and thoroughly. This photo shows two Q-tips in action. The one on the right is for use with the isopropyl alcohol for initial cleaning of the area to be colored and the one on the left is used for cleaning up the extra coloring that is left behind by the paper towels. NOTE: For those of you with a chemistry background, you'll understand that a small volume of both solvents has been separated from the main vessel. NEVER pour used solvent back into the main holding vessel. Whatever volume is initially separated is what is to be used. If there is any extra at the end of the project then it is to be thrown away. Step SIX - Final Cleaning and Detailing
There is no doubt that the colored areas will need some cleaning up. In the above photos you'll notice a line of color that was not intended to be colored in, but inadvertently was (just under the rear sight base at the top of the heel). Using a toothpick dabbed in nail polish remover, I "scraped" the area until the coloring was removed.
After I was happy with the detailing process I applied some MiliTec machine oil to bring the receiver back to a nice black luster.
That's all there is to it. I would say the process takes about a half hour from start to finish, and for many quite quicker. I choose to move slowly and deliberately through it, as I feel it gives me the best results.
If there are any questions, please feel free to ask!