Posted by Rodney Gold in another thread, worthy of being here also.
If you look on www.uksignboards.com and do a search on doming , you will see I have published a huge amount on it.
It's not actually *that* simple as there are some pitfalls
The best material to use for doming is a 2 part urethane (rather than epoxy) or if you have the money a UV curable one part.
The easiest way to get into this is buy a cartridge system with an applicator gun , tho if you are doing volume , this is very expensive , but for a trial system , its fine.
The biggest problem you will have is bubbling and then yellowing. The materials are hygroscopic (attract water) , that and the mixing action introduces air and thus you start getting bubbles in the dome and if the dome gels before you can release them , the item is ruined. the mixing guns will not introduce air or bubbles and all you have to do is pull the trigger , apply the dome and put the domed item in a level warm dry place - heat will accelerate the curing process but is not essential unless conditions are cold moist and damp. We actually put the mixture in a vacuum chamber after mixing to de-bubble it quickly. We have built drying racks using shelving with incandescent 60 w bulbs screwed to the underside of the shelves to heat the one below , we use industrial builders plastic sheeting as a curtain to keep the heat in and stop dust.
The golden rules and some thought are:
1) Do NOT vigorously mix , it introduces air , fold the mixture and let it stand a few minutes after mixing to de-bubble;
2)MOISTURE and to an extent cold is an evil in doming , it will cause all your problems , Dry and warm conditions are VITAL to doming;
3) If bubbles in the dome don't rise before the dome starts gelling , use a flame waved over the dome , makes the liquid more viscous and expands the air bubbles to rise , do not touch the mixture with the flame;
4) Most epoxies yellow and do not have a great adhesion on certain stuff , try avoid them and use urethanes;
5) Do not dome huge areas to start with , practice on small stuff like 1" diameter circles etc.;
6) The longer the pot life (the time the material has before it gels and is unworkable) the longer the cure time;
7) Drying trays MUST be leveled using a spirit level;
8) Urethanes are more difficult to work with than epoxies , start off with epoxy and move to urethane when you are experienced;
9) You can dome just about anything , some papers will get soaked etc.;
10) Be careful with digital printing and the like , it sometimes bleeds into the dome , plasticizes in vinyl will also be a barrier to adhesion with some epoxies;
11) Epoxies and urethanes in bulk are about $15 per kilo mixed (2.2 lbs) and 1 gram should cover 1 square inch;
12) Some UV curables require serious UV sources , not a black light and they can be VERY expensive , the 10 sec UV curable from deco coat is about $210 a gallon;
13) www.mockridge.com , www.cammda.com , www.dopag.com , www.eurodrop.it have supplies and doming machines and some sites have nice tips;
14) Sharp corners do not dome well , when cutting cut sharp bits with a slight radius;
15) Apply the doming in the center of the item , let it spread a bit and then draw it out using a toothpick to the edges if it doesn't get there;
16) Only use flexible on stuff like stickers , badges , key fobs etc use the hard stuff;
17) If you get milky deposits on the surface of the dome a few days/weeks later , the conditions you domed in were moist or cold;
18) Most resins are toxic to some extent , eye protection and rubber gloves is essential;
19) You can use a paper cut and a ice cream stick or tongue depressor to mix and to drip the mixture on the item - drip it , don't pour;
20) if there is a mix ratio , like 1:1 , don't eyeball it , it has to be extremely accurate - a cheap kitchen digital scale will help here
21) The more viscous the mixture and the smaller the part , the higher the dome you can build;
22) dint print too near the edge of anything being domed , the dome acts as a lens and printing or letters right at the edge gets distorted.
Start off , as I say , with a 2 part epoxy that does not require UV.
Doming adds huge value to an item and beautifies it , often turning something ordinary into something extraordinary and enabling you to more than double the price.
Regards
Philadelphia, PA (Really Bensalem)
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