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A short course in doming – tips techniques etc
Doming is an area that adds huge profits to your business and adds amazing value to your products
Doming is really only suitable for smallish areas if you don’t have a dedicated doming facility , trying to dome anything that is over lets say 15cm x 15cm will be frustrating , the dome relies on surface tension and on large areas you get dips in the dome.Basically , doming is the overlayer of an epoxy coating on ANY substrate
Just about anything can be domes to protect it and give it jewellery quality look.The doming resins are fairly viscous , like honey , and even if you die cut a piece of vinyl , you can build a highish dome on it without overspills.
There are 3 types of doming resins , 2 part water clear epoxy , 2 part water clear polyurethanes and 2 part polyesters
a) Epoxys are cheap , easy to work with are easily available and realtively safe re toxicity
They do have certain problems , they are not UV stable and yellow with age or sunlight (you can add uv stabilisers) , they have limited adherance to vinyls or materials which contain volatile plasticisers and sometimes bleed certian types of printing into the epoxy (smears the print a bit) but are the starting point of any doming operation and are availble from glass hard to very flexible (the flexible epoxies are better at adherence)b) Polyurethanes are UV stable , cheap , adhere to anything BUT are very very difficult to work with and are toxic to some extent , you are guaranteed to have problems using them without a dedicated facility
c) polyesters are not water clear , very toxic but very cheap but also can exhibit micro cracking at the dome/substrate syurface
There is one secret to ANY doming attempt , and that is to banish ALL humidity , water is a killer for doming and polyurethanes are VERY hygroscopic , apart from that water promotes aline migration in epoxys and this “blooming” is a cloudy mottled look , they also promote bubbles or bubbling due to their water affinity and these are difficult to remove
Thus the first step is to dome in a dry warm area – this is VITAL for any measure of success , should you wish to use urethanes , then you will have to have an environment controlled room and a vacuum degasser as well as a specialised mixing system to do so if you want to do production volumes
Aeration in the mixing proccess is also a problem , vigourous mixing will induce air bubbles and if you dont remove these prior to the dome gelling you will have a ruined product – try warm the 2 parts of the mixture prior to mixing and leave it a little while to degass itselfAll resins have a pot life (the time that you can use these before gelling) and a cure time (the time before they are handleable) , these 2 go hand in hand , a long pot life means a slow cure time , but for the novice this is the way to go , epoxys with long pot lives are easier to work with and bubble removal is easy.
With ALL resin systems , exact proportions in mixing are critical , a small digital scale is essential – do NOT guestimate quantities.
The process is simplicity itself if you want to do it on a small scale , phone your local resin supplier , ask for a 2 part uv stable water clear epoxy with a pot life of about 20-30 mins , gently , using a sucker stick or tongue depressor , mix a small batch in a paper cup, wait a few minutes for the bubbles to dissipate and gently drip the mixture on to whatever you want to dome (make sure this item is also dry) and let it settle , if the mixture has not reached the edge of the item , add a little more and gently pull the resin toward the edges with the sucker stick , then lay the item flat (flat is also vital if you want an even dome , use a sprit level) and wait for it to dry overnight or so , you can accelerate curing via heat , like a shelf with a bulb above it will allow a faster cure time
There are UV curable doming compounds with 10 sec uv flash cure times and infinte pot life , but these are VERY expensive , require very high powered uv sources and dont build “high” domes (the smaller the object the higher the dome you can make)
If you see bubbles in the item after doming , but before gelling , then take a small pencil type gas soldering torch and wave it over the item , the heat makes the bubble rise and burst on the surface.I repeat , moisture is a KILLER , most problems you will have are due to cold temperatures and moisture!!!!!!!!!!!!!!!!!!!
Do NOT mix massive quantities as most resins tend to go exothermic , IE promote a heat reaction and you will end up with a foamy hot solid mess in 3 minutes
You need about one gram of resin for every sq inch as a rule , resins normally can be had for R200 a kilo (about GBP8 per lb)
with one kilo of resin one can dome about 1000 1″ diameter discs at a cost of about 1.5 pence a piece (im not sure what resin prices are like in other parts of the world)Its real cheap , but a little labour intensive , but the profits are stupendous , for example our soljet ort pc60’s printing graphic and die cutting it can do about 800 1″x2″ stickers in a sq meter , we would normally sell them at 3-4x cost of material , but adding a dome bumps them up to 12-15x the cost.
Often we digitally print Vinyl , apply it to a brass back or blank cut on one of our CnC machines , dome the WHOLE thing , and voila – you have a jewellery quality badge you can sell at VERY high prices.You can apply resins to just about anything you want, coins , medals , trophy inserts , vinyl cut letters (on the carrier) make keytags , make all sorts of flexible and protected labels etc.
It’s really worth a try!!
The commercial “kit” type doming systems I have seen are really very overpiced IMHO and reading one of the threads here , the problem of shelf life rears its ugly head
Resins are toxic and are irritants , its always best to wear surgical gloves and some form of safety glasses when working with them
You can add transluscent pigments to resins to give some nice effects
If anyone want more or more specific info , just ask:) -
1 Reply
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Very interesting.
…..”I repeat , moisture is a KILLER , most problems you will have are due to cold temperatures and moisture!!!!!!!!!!!!!!!!!!! “……
Now don’t forget Rodney most peeps on this board
LIVE & WORK IN BRITAIN!!!We don’t get 25 degree temperature most of the year in this hell hole 😆
I am quite happy to stick with my “overpriced” dispensers! 😉
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