How to get scratches & gouges out of slabs
BryceM
Posts: 11,814 ✭✭✭✭✭
This topic comes up every once in a while. Earlier today a member asked how to get a slab re-holdered and re-stickered. It seems much easier to me to just get rid of the scratch (or gouge). I offered advice via PM and received a number or requests for "how I do it."
First, I emphasize that experiment with whatever method you choose on something inexpensive, or even better, slab remnants from coin crackouts. It's difficult to mess up a coin, but people are infinitely creative and I'm sure someone out there will cry foul when their method results in a small explosion, a lost eye, or a coin that is cut in half. If you're not familiar with basic power tools, the English language, or how to cook Ramen noodles, maybe this isn't for you.
Second, a little background. The plastic used for the various slabs varies quite a bit and what works on one thing may not work well on something else. A little experimentation is sometimes required. Also, some slabs really are beyond help and re-holdering is the best options for them. The vast majority of slabs can be successfully restored though, even with deep scratches or gouges that initially appear hopeless.
I'll tackle the most common scenario, that of a post-rattler PCGS slab with a few abrasions or light digs over the coin. The newest, clear-plastic, slabs with the gradient-tint labels are much more scratch resistant than the old solid-blue-label holders that were being made a few years back. When these get abrasions they're pretty easy to work with.
For some reason, areas of patchy roughness seem to congregate directly over the center of the coin obverse. For the majority of cases I use Meguiar's PlastX, which was originally intended for auto headlights. This can be found at any auto supply store. I usually pick up a few microfiber cloths to use, but almost any clean fabric (without embedded dirt) will do fine. The trick here is elbow grease. Apply a couple mls of the stuff on the slab and get to work with the rag. If the scratches run north-south, it's usually best to polish from east to west. To check my progress I hold the slab at an angle to the light (like you would to to check for putty) and visualize the surface of the slab with my loupe. This method will work for even very deep gouges, but it can take a LOT of effort and usually isn't worth it.
A circular polishing wheel is available that will fit on a regular drill that takes much of the effort out of the process, but it takes a little attention to make sure you aren't creating as many circular scratches as you're removing. it won't polish in only one direction. If you use this, figure out how to secure the slab securely so it doesn't fall on the concrete floor and break in half. Ask me how I know this this......
For deeper problems, including linear scratches, I turn to Novus #3. I'm not sure what exactly is in this stuff, but it's abrasive and it will produce a millions of superficial slab scuffs and abrasions. Don't worry about it! These will be removed later. Focus on the gouge and work parallel to it. Don't worry about the haze and opacity that develops where you're working. It might take lots of effort. Use a good quantity of the stuff and use a fresh helping every so often. Eventually you'll wear away enough plastic that the scratch is gone. Once you're at this point, wipe off everything carefully and go to Novus #2. I use this for a while until I'm down to a more-or-less clear slab with trivial little scratches. The final step is to go back to the PlastX and repeat the steps above. Be sure to use a clean cloth, or you'll continue to drag the abrasives in the Novus around, causing new problems.
Finally, for the truly abused slab with rototiller furrows, you'll need to get serious. Tighten your suspenders and bring out the big guns. Sandpaper can be used to accomplish just about anything. The key is to start with something coarse (around 800-1200) grit until the original problem has been eliminated. Once you're done with this the slab will look horrible. The coin will only be faintly visible. Use a fresh area of the paper frequently. Once you've done what you need, move to a finer grit, say 1200, then 1500, then 2000, then 2500. Many of these work best when wet. Take your time. After the 2500 stuff, the slab will be ready for Novus #3 (preferably with a power tool), then Novus #2, then PlastX.
I'll edit this post to show some photos later this weekend when I have a little time.
A few final tips. Don't try a high-speed tool like a Dremel. These can work, but it takes tremendous care. They can very easily heat up the plastic to the point that huge volumes of slab material starts to move around or discolor. Once that happens, you're done, and it's even possible to burn through the slab and destroy the coin. For stubborn scratches I'll sometimes keep the slab under the halogens for a few minutes to warm it up. This seems to soften the plastic a bit and makes things go faster. If nothing is happening, push harder and work up a sweat. Use new polishing material and a clean cloth. Keep the polishing stuff away from stickers, as it will tend to damage the top layers and leave them ugly. NGC slabs are harder to work with. Sometimes it takes a very careful touch to not cause more problems than you're fixing. A large buffing wheel on a grinder motor works beautifully, but these have a funny habit of catching an edge and spinning the slab 30' across the room....... not a method for me.
I've tried to look at $250,000 coins in Platinum night auctions that you couldn't even see through a cloud of haze. The sticker people have indicated that they sometimes reject coins outright simply because they can't see the coin! Think about it. I haven't re-holdered a coin for slab scratches in years, and I photograph every coin in my core collection. I see coins in Heritage, Stacks, and Legend auctions all the times that feature prominent slab abrasions that could have easily been removed. Even the very best photographers working for the very best dealers will sometimes let slab ugliness get through to the final product. On $100 coins I understand that it isn't cost effective, but come one, a slab scratch in a full-page photo of a $100,000 coin? Puh-lease! 17.5% = $17,500 commission. There should be room in there somewhere to hire a dropout to polish a slab for 5 minutes.
This slab was real challenge, and I wanted to preserve the OGH. It was sent to the sticker people before I photographed it and was rejected. When it got back I tried a 30 second polish job and ended up with this:
I then got a little more aggressive with Novus #3 and got this. As you can see there are still some serious problems:
A little elbow-grease and about 15 minutes of cussing produced this, but I didn't resort to any sandpaper:
A few months later I got over the OGH label and included the coin in a regrade submission. It came back AU53 and stickered.
This photo was on the website of a VERY respectable and amazingly good dealer:
After it came in the mail I worked on this one with only PlastX for about 30 seconds per side and took these photos:
First, I emphasize that experiment with whatever method you choose on something inexpensive, or even better, slab remnants from coin crackouts. It's difficult to mess up a coin, but people are infinitely creative and I'm sure someone out there will cry foul when their method results in a small explosion, a lost eye, or a coin that is cut in half. If you're not familiar with basic power tools, the English language, or how to cook Ramen noodles, maybe this isn't for you.
Second, a little background. The plastic used for the various slabs varies quite a bit and what works on one thing may not work well on something else. A little experimentation is sometimes required. Also, some slabs really are beyond help and re-holdering is the best options for them. The vast majority of slabs can be successfully restored though, even with deep scratches or gouges that initially appear hopeless.
I'll tackle the most common scenario, that of a post-rattler PCGS slab with a few abrasions or light digs over the coin. The newest, clear-plastic, slabs with the gradient-tint labels are much more scratch resistant than the old solid-blue-label holders that were being made a few years back. When these get abrasions they're pretty easy to work with.
For some reason, areas of patchy roughness seem to congregate directly over the center of the coin obverse. For the majority of cases I use Meguiar's PlastX, which was originally intended for auto headlights. This can be found at any auto supply store. I usually pick up a few microfiber cloths to use, but almost any clean fabric (without embedded dirt) will do fine. The trick here is elbow grease. Apply a couple mls of the stuff on the slab and get to work with the rag. If the scratches run north-south, it's usually best to polish from east to west. To check my progress I hold the slab at an angle to the light (like you would to to check for putty) and visualize the surface of the slab with my loupe. This method will work for even very deep gouges, but it can take a LOT of effort and usually isn't worth it.
A circular polishing wheel is available that will fit on a regular drill that takes much of the effort out of the process, but it takes a little attention to make sure you aren't creating as many circular scratches as you're removing. it won't polish in only one direction. If you use this, figure out how to secure the slab securely so it doesn't fall on the concrete floor and break in half. Ask me how I know this this......
For deeper problems, including linear scratches, I turn to Novus #3. I'm not sure what exactly is in this stuff, but it's abrasive and it will produce a millions of superficial slab scuffs and abrasions. Don't worry about it! These will be removed later. Focus on the gouge and work parallel to it. Don't worry about the haze and opacity that develops where you're working. It might take lots of effort. Use a good quantity of the stuff and use a fresh helping every so often. Eventually you'll wear away enough plastic that the scratch is gone. Once you're at this point, wipe off everything carefully and go to Novus #2. I use this for a while until I'm down to a more-or-less clear slab with trivial little scratches. The final step is to go back to the PlastX and repeat the steps above. Be sure to use a clean cloth, or you'll continue to drag the abrasives in the Novus around, causing new problems.
Finally, for the truly abused slab with rototiller furrows, you'll need to get serious. Tighten your suspenders and bring out the big guns. Sandpaper can be used to accomplish just about anything. The key is to start with something coarse (around 800-1200) grit until the original problem has been eliminated. Once you're done with this the slab will look horrible. The coin will only be faintly visible. Use a fresh area of the paper frequently. Once you've done what you need, move to a finer grit, say 1200, then 1500, then 2000, then 2500. Many of these work best when wet. Take your time. After the 2500 stuff, the slab will be ready for Novus #3 (preferably with a power tool), then Novus #2, then PlastX.
I'll edit this post to show some photos later this weekend when I have a little time.
A few final tips. Don't try a high-speed tool like a Dremel. These can work, but it takes tremendous care. They can very easily heat up the plastic to the point that huge volumes of slab material starts to move around or discolor. Once that happens, you're done, and it's even possible to burn through the slab and destroy the coin. For stubborn scratches I'll sometimes keep the slab under the halogens for a few minutes to warm it up. This seems to soften the plastic a bit and makes things go faster. If nothing is happening, push harder and work up a sweat. Use new polishing material and a clean cloth. Keep the polishing stuff away from stickers, as it will tend to damage the top layers and leave them ugly. NGC slabs are harder to work with. Sometimes it takes a very careful touch to not cause more problems than you're fixing. A large buffing wheel on a grinder motor works beautifully, but these have a funny habit of catching an edge and spinning the slab 30' across the room....... not a method for me.
I've tried to look at $250,000 coins in Platinum night auctions that you couldn't even see through a cloud of haze. The sticker people have indicated that they sometimes reject coins outright simply because they can't see the coin! Think about it. I haven't re-holdered a coin for slab scratches in years, and I photograph every coin in my core collection. I see coins in Heritage, Stacks, and Legend auctions all the times that feature prominent slab abrasions that could have easily been removed. Even the very best photographers working for the very best dealers will sometimes let slab ugliness get through to the final product. On $100 coins I understand that it isn't cost effective, but come one, a slab scratch in a full-page photo of a $100,000 coin? Puh-lease! 17.5% = $17,500 commission. There should be room in there somewhere to hire a dropout to polish a slab for 5 minutes.
This slab was real challenge, and I wanted to preserve the OGH. It was sent to the sticker people before I photographed it and was rejected. When it got back I tried a 30 second polish job and ended up with this:
I then got a little more aggressive with Novus #3 and got this. As you can see there are still some serious problems:
A little elbow-grease and about 15 minutes of cussing produced this, but I didn't resort to any sandpaper:
A few months later I got over the OGH label and included the coin in a regrade submission. It came back AU53 and stickered.
This photo was on the website of a VERY respectable and amazingly good dealer:
After it came in the mail I worked on this one with only PlastX for about 30 seconds per side and took these photos:
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Comments
coin and banknote dealer since 2003
I too agree that auction houses should polish a few slabs from time to time but should then go a little further and actually PHOTOGRAPH coins over $500 in the cases where scan-like images are used. And then I take it further to plead with auction houses to eliminate the FALSE ADVERTISING that has become so pervasive in this industry by doing away with the stupid fantasy photos where nearly all black coins are shown as white with fantastic rainbow colors where the coin looks NOTHING like the coin in hand. Pure stupidity and pure FALSE ADVERTISING!
Looking for Top Pop Mercury Dime Varieties & High Grade Mercury Dime Toners.