Removing a coin from a lucite/acrylic paperweight block.

Unless coins were really valuable, I wouldn't touch it. Freeing the coins will take a lot of work and solvent plus a band saw or table-mounted jig saw. Mike

 

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I wonder what happens if you soak it in liquid nitrogen and then smash it with a hammer?

 

I tried putting a chunk in the freezer and then hitting it with a hammer. It did shatter, and I got coins out, but several of them were bent from the stress/strain. (These were clad and polished, so no great loss.)

 

So liquid nitrogen might work, since the block would be way way colder and perhaps less force needed to shatter it.

 

Might try thermal stress cracking. Use dry ice to cool. Dry ice is usually much easier to obtain than liquid nitrogen … many grocery stores carry it. However, dry ice is not as cold as LN but is not as dangerous to handle either. Wear thick gloves and remember it continuously generates carbon dioxide gas. Once the block is completely at dry ice temperature, drop it in a pot of boiling water or, even better, cooking oil that is near boiling. Be careful not to get splattered.

Mike

 

I'm not enough of an engineer to calculate the forces and effects on a coin from this thermal-stress approach, but I'm not confident that it would be safe for the coin(s). The thermal stress on the coin shouldn't matter, but the forces from the deforming plastic might.

 

With a bandsaw you could cut away the greatest majority of the plastic, then use the acetone to individually free each coin.

 

That's more time, though. Especially when the plastic softens due to friction and jams your saw blade. Ask me how I know.

 

I believe the answer is as would be mine: As it's probably an unequaled challenge for most, but desirable for some!

I've rolls of that coin/condition, but I'd loved to secure it in my milling machine, cutting parallel to the coin body faces within .03", and within the same of the diameter edge, before putting it in my hydraulic press between 2 rubber sheets.

Lightly press, POP/FREE!

A COUPLE HOURS STRESS-RELIEF WHILE WORKING ON OTHER CHALLENGING PROJECTS!

I completed a portion of this exercise often, when relieving slabbed Gold Eagles from their "cage", for TPG re-submission!

 

Yup, the usual blades made for wood and metal are melt-city when used on plastic. However, there are special saw blades and drill bits made for plastic. I know from experience they make a huge difference. Buying them for a one-off, inexpensive project ... probably not worth it. Mike

 

Try microwaving it! LOL

Put a shrimp on the barbie!

 

I went to take a look and it was gone.
Someone bought it for what it was... probably at today's $17.50 price tag.

 

Yep, sometimes you get beaten to the punch. This probably isn't one to loose too much sleep over, though.

 

No sleep loss at all.
I ended up picking up a sterling silver Taxco pendant for $0.50
An interesting box of rocks for $20 with one rock looking like it has a little bit of gold in quartz.
A large black mixing tub for $2.50 and a tile/rock saw on a cart for $75.

 

good job

 

I have been in the Lucite business since 1968. It is best to leave this to a professional. anything can be removed from Lucite without any damage to the item. Some things by law are not to be removed such as a police or law enforcement badge. Coins value are diminished when they are removed by beating them out as it leaves permanent marks on the item removed. The chemicals used to melt acrylic are dangerous and odious (flammable and omit dangerous fumes)
Bob
Crystal-Like Plastics

 

Do you have better/cheaper choices than acetone? I guess paint thinner or even gasoline would also work, but I'd hate cleaning up after it. At least acetone is relatively non-toxic, although it's flammable enough that I'd hate to call it "safe" in the quantities needed...

 

Some solvents will dissolve polymethacrylates faster than acetone. Examples are tetrahydrofuran, chloroform, and methylene chloride. As to safety, it depends on risk balancing. For example, unlike acetone, chloroform is not flammable; however, it’s a potential carcinogen and an ozone depleter, although it doesn’t last long in the atmosphere. Obtaining some of these solvents is problematic for most folks. Mike

 

Ah, yes. I was surprised not too many years ago to see bottles of "plastic weld" that was still pure chloroform. I could've bought all I wanted, two ounces at a time.

I haven't had the "pleasure" of working with THF, and probably never will. Unless I somehow manage to get a fume hood.

 

Wonder how that would go putting metal in the microwave. Probably cause hot spots on the coin and in turn discoloration. Wonder if you could submerge it in a hot pot full of already liquified Lucite and slowly melt the coin out.