Need help finishing spin cast medals.

[Mark Gruninger]

I have sucessfully been able to cut a model and mould on my laser for spin casting inexpensive medal for golf tags. I am having a hard time figuring how to finish them. They are very rough looking and I would like a gold or bronze smooth finish with a little shading or "antiquing" of the recessed areas to highlight the details on the metal. I heard a metal tint and dipping process might work, but I don't know where to buy the paint or tint or what process to follow. Any help is greatly appreciated.

[art baylor]

Can you post a photo of the unfinished piece?

Art

[Mark Gruninger]

I will try to post it when I get into the shop tomorrow. But, they come out silver looking - very dull and rustic looking. I have tried spray paint, but it is not transparent enough to show detail. I have heard of oxidizing the metal but it turns it black and then they have to be buffed to remove the excess black residue from the piece. I really need help with this. I don't have the money to buy an electroplate system or take them to be electroplated. They are very inexpensive pieces not a high quality item like coins would be. Thanks for any advice !!

[Rodne Gold]

You need to take em for electroplating , either they must use an Antique copper or antique brass plating.
The cost of electroplating these should be minimal , a lot less than the time you spend doing it yourself.
Next time , use a spin caster that provides you with a finished product, most of em will have in house plating/polishing/tumbling machinery.
The only thing I can suggest if you want to do them yourself is to buff and polish each side , spray with black spray paint and remove the excess off the polished surface leaving the black in the indentations , a very time consuming laborious process.

[Mark Gruninger]

I acquired the spin casting equipment along with the tumbler to smooth the cast medals or pieces. The company I purchased the spin casting operation did not know how to achieve the different color finishes. I have a golf operation that wants bag tags for the members as well as multiple tournaments they host. Each order is from 100 tags to 1000 tags. I don't have much trouble if they want a pewter finish. I have been oxidizing the piece and then buffing off the excess, and yes, it is alot more time consuming than I thought it would be. I have not been able to achieve a good result with gold or bronze finishes. I have searched and called about ecoating but I can not afford to invest in this process and didn't think I would have to. This metal casting is certainly not as easy as I thought it would be. Please any help with my problem would be greatly appreciated. Thanks!!! Ps I'm in too deep to bail now.

[Richard Rumancik]

Hi Mark

You haven't said what the metal is - pewter? zinc?

You might take a look at
http://www.caswellplating.com/

They sell a lot of kits for small-shop DIY plating, powder coating, etc. They may have some dip-type chemicals instead of full-blown electroplate. If you contact them maybe they can help. Their chemicals tend to be lower toxicity /lower risk than many of the commerical plating solutions.

You could also do web or library searches on jewelry making, and see if any of the dip coatings used are applicable to your situation.

If you are close to a plater you might just ask what they charge for barrel plating a batch of medals. You might get a better price than you think. If you can get 1000 pcs plated for $50 I'd probably take it.

Doing a dip finish in-house sounds feasible but in-house electoplate for 1000 pieces seems a bit too much to tackle. But if you really want to do say 100 pcs in house you can set up a power supply pretty cheap. Get an electrical technician to give you a hand if you need some help. It is basically a variable DC power supply. You can find more info at Caswell on this topic too.

[Marc Myer]

Caswell is a good company; I've purchased from them in the past.
Another good company is www.goldtouchinc.com (http://www.goldtouchinc.com). They have a number of innovative and cool coating systems.
No, I'm not connected with them, but I've purchased from them and even had some free training at their office in Cleveland. Worth looking at.
marc

[Ken Gastineau]

Mark:

I am not sure how much help I can be, but I do work with pewter and spin casting. There are many factors involved in producing good quality castings including choice of rubber, alloy, model design, mold temperature, alloy temperature and mold design.

First of all the model must be designed to produce a good quality casting. It is very difficult to cast something that is not designed to be cast.

It is best to match the rubber with the alloy. There are many rubber formulas for centrifugal mold casting and some work best with lead based alloys and others work best with lead free alloys. I do not work with lead based alloys so I have no experience in that area. Your supplier can steer you towards compatible products.

Depending on your model design there are different alloys of pewter that will cast better for some applications than others.

The temperature of your alloy and mold at the time of casting will also effect the quality of your castings. Keeping your molten alloy clean is very important.

Mold design is also very important as this also effects the final casting quality. Making sure the mold is properly vented is important as well as your stategy for supplying metal to the mold cavity.

I have no experience with plating pewter, but I hear that the right choice of alloy can be very important if the castings are to be plated as some alloys can produce very porous castings.

I use Pewter Black to darken casting in preparation for brush finishing or tumble finishing. It turns the pewter black and the idea is to remove it so that the outlines or background have some definition when finished. Tumble finishing works pretty well if you understand the basic principles of tumble finishing. It can be a nightmare if you do not understand these basic procedures. A good supplier can steer you in the right direction (maybe).

A picture of your castings would give me an idea as to whether you are experiencing a casting problem or a finishing problem. Is it possible for you to post some pictures as both raw castings as well as finished pieces?

Ken Gastineau
Gastineau Studio
Berea Kentucky