Hi, I recently cast a cube and I found the best way to get a perfect cube is to plane the edges and then sand with 800, 1200, 1500 grit paper and then polish with 10000 grit polish...this works great on epoxy castings but takes FOREVER with smooth on crystal clear 204 as it is 80D and super hard...
Any tips on how to do this easier ?
Any tips on other products I should be looking at that are clear, UV stable, and polish much easier after sanding ???
No experience with epoxy polishing, but with glass - another hard material. Wet and dry papers work well when used wet, preferably with a power sander. After that I have used diamond pads. A rubber sponge, one side coated with diamonds in epoxy. Use it wet, apply some preassure. Final polishing I have made with suave leather andvalve honing paste that is available thru car repaisr shops.
For glass one might try cerium oxide - used in the optical industry for polishing lenses and lapidary usage is for softer stones like quartzes. There are commerically prepared polishes for acrylics which will probably work on the epoxy - I use watch crystal piolishing compounds on two part (epoxy) enamels.
Steve- check out my other response for a better alternative.
as to polishing- generally, the harder a material, the easier it is to polish to an optical finish. For flat faces, use a power polisher and belt sander, Start with a much coarser grit to get a fair surface more quickly and then move up thru grit rapidly.
This implies 'faster, better, cheaper' - in which case you should probably be spraying a clear coat over the sanded resin - sanded to 200 grit only so there is some tooth for the spray. You got off lucky with the square, flat surfaces of a cube - wait until you have to buff out a many contoured piece. Also make sure your mold surface is highly polished, for a cube you can cast off a plate glass piece mold(S)?
Try automotive clear coat lacquer to start with, to learn technique, safety and get your airbrush up to speed. The very best is aliphatic urethane with UV inhibitors - super hard, super glossy, super weatherproof, protects the epoxy (to some degree) but also the trickiest to spray and moderately toxic. Fog coat, fill coat, finish coat - no buildups or runs please. You can also do many effects such a glazing (transparent red, transparent yellow, to make orange) and special effect pigments such as pearl and holographic flakes. These coatings have the advantage of drying/curing very quickly.
If you are making to customer specs, get an exact number or reference as to what 'smooth' or 'glossy' actually means. This can range from a sample to match, to exact words ('class 1 automotive' finish for example) to a specific reading off a fairly expensive glossometer testing machine.
This also answers your UV stable epoxy resin enquiry too. Epoxy is the vampire resin - it has to be sealed from UV, even if UV inhibitors are in the resin, the surface still yellows and dulls. This is a marine rule of thumb, if this is a piece which will find a permanent home on the mantelpiece of your secret underground stronghold, don't worry about it.
I had trouble getting the Smooth-on 204 to buff out myself. You might try Polytek Poly-Optic 1420 which is actually designed to be machined and polished (though you have to heat-treat it) and it is super-sensitive to moisture. Have you tried a buffing wheel on a bench grinder with plastic
Are you saying that a buffing wheel will make polishing 204 easier ? what kind/brand of polish works best (meguiar's) ? At what grit should I stop sanding and start polishing ??
can anybody help me with crystal clear lifecasting techniques. what are the chemicals used in these. can you use an alginate mold for the same.
alginate molds can not be used to cast Crystal Clear urethane resins because urethanes are moisture sensitive and since there will be moisture present in your alginate mold, the resin WILL cure with bubbles and cloudiness. It will be a waste of time and money.
This is a scenario where the casting media drives the mold material choice and the process involved.
hi ,,thanks for the same.
could u please help me further please.
what material is used for crystal casting.
what material for taking impression.
would be glad if u could help me
what are you taking an impression of??
I tried lifecasting of baby hands and feet. i used alginate for impression and used plaster of paris for mold.
now i came across crystal life casting through website http://www.crystalkeepsakes.com.au/shopexd.asp?id=182
i would like to know what chemicals are used for impression and mold.
Could you please help.
Thanks for your replies till now
The impression material is alginate which is a powder that is mixed with water to take the impressions; I prefer using Alja-Safe, which does not contain any crystalline silica (a known carcinogen. http://www.smooth-on.com/Life-Casting-Alja-/c3_1185/
I have no idea what the casting media is, but am pretty sure it is not a urethane. It may be an acrylic or possibly a polyester - based resin. It's interesting, they do not offer any instruction on the website or information about what the resin is...
Use wet/dry sanding paper wet. I'd hold it over a bowl of water to keep it good and wet while I work.