Saw a news program on T.V. last night where they took a gun that had the stamped serial number ground off and after determining what the composition of the gun metal was they used some kind of acid to wipe over the area where the number had been ground off and it re-appeared for an instant. Is something like this possible on a engine pad ?
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Re: Engine Pad Stamp
Yes it is. Not sure who you would have do it, maybe the police department, I know the State Patrol in CA can check stolen and restamped Porsche Engine cases, Harley Davidson cases etc. -
Re: Engine Pad Stamp
Wayne-----
Yes, it is possible and it's a technique that's been used by law enforcement agencies for years to "raise" serial numbers or ID marks from a variety of things, including automotive components. It seems that the grain structure of the metal is "disturbed" well below the area that the actual metal is "upset" by the stamping operation. Assuming that not too much metal has been ground away in the effort to remove numbers, intentionally or inadvertantly, the numbers can often be discerned or "raised" by using the acid technique.
This sort of procedure falls under the general heading of forensic science. Consequently, there is not too much expertise performing it outside of forensic laboratories and professionals.In Appreciation of John HinckleyComment
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Re: Engine Pad Stamp
I have done this. In the archives you will find some of my earlier posts about it. A law enforcement officer provided me with some "10% ammonium persulfate acid" which I brushed on the pad. It is so dilute that it works very slowly. It takes a long time and you have to be patient. As it etches down, some numbers are revealed. Don't be fooled into thinking that ALL the numbers may be revealed at the same time. The visibility of the numbers is a function of the depth/pressure that was applied by the stamp, so the more lightly struck characters may reveal themselves earlier in the process (and disappear early in the process also), and the heavier struck characters will tend to stay visible the longest. As you continue the process, the lighter ones will disappear as you etch down through the impacted region. Once they are gone, they are gone. Take pictures very often through the process. I kept going and eventually went too far (meaning that most of the characters I had seen earlier on the process had disappeared). This phenomenon is a function of the density of the area being etched - underneath a stamped character is a region of more dense material and the etch characteristics are different for areas of varying density, thus the stamped areas reveal a visible pattern compared to unstamped, less dense areas.Comment
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Re: Engine Pad Stamp
Everett,
Thanks for your response. If I may I have a few more questions.
1) When you say it takes a while are we talking minutes, hours, etc.?
2) Do you apply the acid once or do you need to keep the surface wet?
3) What do you use to neutralize the area when your done?
4) Is this a one shot deal or could it be done again?Comment
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Re: Engine Pad Stamp
Let me clarify - it is definitely a one-shot deal, as far as if you etch far enough so that you can't read a particular number anymore, then that number is lost forever. If you mean - can I start the process, and then neutralize (with water), dry it, and then continue the next day - yes, you could do that.
In my case, the milling on my pad was not too extensive - I could still read a couple of the characters. But the acid was so dilute that it still took the better part of a day. I would apply some acid to the entire pad with a Q-Tip and rub it around, then apply some more, etc. About every 5 or 10 minutes, I would wipe it dry and do a close exam, and maybe take a photo. As I said, I did not really realize at the time that the numbers that "appear" first, would also disappear if you keep going (to uncover the other characters). So, go slowly and document what you see, b/c it may disappear as you go "deeper".Comment
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Re: Engine Pad Stamp
Everett-----
Yes, and your description of the process also brings to attention another point that I failed to make in my first post. The acid process WILL NOT RESTORE the stamped numbers to an engine stamp pad (or whatever else one uses the process for). It will only help you, POSSIBLY, determine what the numbers were originally. For most restorers, I don't see what the real value of this is. Documentation via pictures that a particualr engine block is, indeed, the original engine block will not, as far as I know, be a substitute for a properly stamped block as far as the judging process goes. So, there are several possible scenarios:
1) you find that the block is, indeed, the original block that came with the car. In that case, you still have to restamp it to make its configuration conform to judging standards. Is a restamped block that was original to the car somehow better than a "restamped" identical block that was not original to the car? They are both restamps. If a judging organization detects the restamp of a block, will they accept it if one can show "photographic proof" that the block was really the original block. How does one document that the "photographic proof" is actually of the block that is in the car?
2) if you find that the block is not the original block, then the process of "raising" the numbers has gained you nothing of value. You now KNOW that the block is non-original. Not knowing if the block is original, or not, is, in my opinion, a better state than KNOWING that it's non-original. Then, you still have to decide if you want to restamp the block. But, now you KNOW that it's non-original;
3) the number raising process raises no numbers or the results are inconclusive. In this case, you're just about in the same situation as in (2), above.
I can't see any other possible scenarios that can result from the process of "raising" numbers from a block stamp pad. While the number "raising" process has definite value from a forensic perspective (i.e. theft or stolen property detection/verification/criminal case evidence), I don't really see what value that it has from a restoration perspective.
Don't misunderstand, though, I am not offering any criticism of using the process of "raising" numbers if one so desires, but I am just offering the opinion that I really do not see what, of value, that it produces for the restorer.
Perhaps the whole discussion just hi-lights how arcane this whole issue of "original numbers" really isIn Appreciation of John HinckleyComment
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Re: Engine Pad Stamp
I attempted to use this process last year when I found out that an old 396 block I had laying around in the garage had an assembly code for a 1965 Z-16 Chevelle. The VIN had been struck so lightly that the last 3 or 4 digits were illegible. My hope was to "raise" those digits and make an effort to reunite the original block to the car, if it still existed. The process in my situation did not work with the missing digits although it did make those digits that were barely readable more pronounced. Just one more scenario.Comment
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Re: Engine Pad Stamp.. tank stickers too ??
is there any thing like this for tank stickers that are too poor to read?Comment
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