Numismatic and History Discussion Forums > Coin Photography, Conservation and Storage

Making plaster casts of coins

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bruce61813:
JD, if you can find it is a hardware store, try Rock Hard Water Putty, it mixes with water like plaser of paris, but is brown/tan in color, and as the name implies, rock hard when it sets. It is less brittle and has a fine grain that hold very sharp detail.

Bruce

Jeremy W:
I went to an arts and crafts store this weekend and bought the clay and plaster.  I have not been able to stop playing since I got home.  At this rate I will have 1000 casts before long.

Curtis,  the instructions are flawless and the process is simple and fun. 

I am in between cameras so I can't post pics just yet but they look so cool!!!!!

Thanks Curtis:)

Jeremy

Scotvs Capitis:
If you are serious about doing some two-sided casts, research RTV rubber molds and Alumalite resin. Scale modelers use this stuff (I have cast very fine detailed tiny parts) and there are ample how-to sites out there on the web. I would recommend the squash casting method - two part mold with alignment pegs cast into the mold, fill each side with resin and place together, effectively squeezing the excess into a paper thin flash. Resin hardens chemically in minutes and can be painted and weathered realistically, and as it is plastic won't be mistaken for the real thing.

I may do some myself, but I have to obtain worthy coins first!  ;)

Scotvs Capitis:
Here are some links about casting in resin. The quality of the resulting duplicates on a few of the websites is not that good but the method is the same (use care and don't be sloppy, RTV replicates the most miniscule detail)

http://www.largescalecentral.com/articles/view.php?id=42

http://www.freemansupply.com/moldmaking.htm

A more involved mold how-to posted on this board, but shows what I mean by alignment pegs: http://www.hobbyfanatics.com/index.php?showtopic=5150&pid=69562&mode=threaded&show=&st=&

These guys sell a starter kit that is reasonable, if you are frugal with materials the kit should allow you to cast many coins. I have used their RTV formula and their resin before, both are excellent. Resins must be properly measured and well mixed or they will either be too oily when hard or they will not cure fully and will be soft. This pour-a-cast stuff is especially prone to being soft if not measured properly, but when done right it is a wonderful resin, bright white. http://www.bare-metal.com/starterkit_files/starter_kit.html

Alumilite is the other resin I prefer, in fact I like it best but my local supplier sells Pour-A-Kast so I buy it because of convenience. Alumilite is the best quality resin commonly available. On their site they have a wonderful series of how-to articles including one part molds, squish casting and others: http://www.alumilite.com/index.php?page=show_how

Jeremy W:
Here is a picture of my first attempt at casting.  I need to work on it more but it is a whole lot if fun and kind of neat. 

Jeremy

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