Doming

[Rodney Gold]

Becky , the height of the dome depends on the are of the decal , the smaller it is , the higher the dome. Apart from that it dpeneds on the viscosity and type of resin being used , the higher the viscosity , the higher the dome. Ask the resin suppliers for a higher viscosity resin (tho this might influence the durometer hardness of it) Epoxys normally go exothermic and thus generate heat which reduces viscosity , some uretanes are better served by doming in very cold conditions and then only curing in hotter ones.
We often put our urethane mixer and pinch valve in the freezer if doing interrupted doming.

[Andy Gorman]

I agree with the above comments by Rodney. However, another factor that I found was relevant to how much resin I could pour when doming, was the vinyl being used. I have found that the resin would spread quicker on certain vinyls, such as polyesters, and therefore would spill if too much was put on, whereas a calendered vinyl would allow more resin to be poured achieving a higher dome. Presumably because of the momentum of the resin hitting the edges of the vinyl. This may have been a characteristic of the particular resin we used and may not be true for all.

[Robert Lambie]

good thread guys.. reading with interest here… 😉 thanks

[Andy Gorman]

Rodney’s comments about temperature could be very significant. I was told by our more scientifically minded staff once, that the room temperature should be controlled (at minimum 25degC) and humidity should be kept below 30%. We therefore had strictly controlled conditions for storing and pouring resin and it did make a difference, mainly to curing times. That is to say the resin stayed “liquidy” for longer when the humidity was kept down, allowing it to flow into some quite detailed shapes. Again, this was the case for the resin we used and may not apply to all types/makes. Incidentally, we used the Interfax Accuflow stuff.

[Mark Shipley]

Hi all, I find the following works really well for doming.

Buy a heated propagator from a garden center and keep all the bags of silica gel that come with doming fluids, machinery etc. in air tight boxes until needed.

Set up and level your trays in the propagator with the silica gel bags at the bottom and dome away! Put a few ‘dots’ of liquid along side the domed badges so you can tack test them to see if you can add more fluid to build up those domes.

The heat from the propagator keeps the doming nice and warm, the silica keeps the humidity down and the clear plastic propagator lid provides a clean, ‘dust free’ environment whilst allowing you to keep an eye on the progress of the curing.

I use liquid lens products which really do build a high dome if that’s your thing 😉

[Rodney Gold]

If you use the correct urethane , then all thats needed is an oven set to about 40 degrees , put the output on trays and the domes will be dry in 20 mins or so. The difference between an epoxy and a urethane is that the epoxy catalyses and the urethane polymerizes. High domes are not always that desireable , especially if you need flexibility. Depending on the hardness of the dome , often a high dome pulls the edges of the domed label off the product as it tries to “remember” its shape.
A very nice production type doming system can be obtained from Cammda (www.cammda.com) or for a much cheaper option , the larger gun (400ml one) from Mockridge (www.mockridge.com) I think the mockridge system is 195 quid with 2.4 litres of doming , guns , de bubblers etc – 1ml = 1 sq inch of doming

[Lee Jones]

@ lasabledps

quote :

Buy a heated propagator from a garden center

Brillient !, never thought of that one….. Just goes to show what a little lateral thinking can acheive, on my travels today i think i will pop in to the local “Cheapy store” , and get one of these today, probably going even cheaper at this time of year.

Trouble is, I Have been Doming for a number of years on a slab of marble (24″ square) which provides a very flat (heavy) smoothe, easily cleaned surface, but do they make them to accomodate this size, or will i need to use something else for the base, What do you use ?

[Mark Shipley]

The propagator I use cost about £30 ish and measures 550x330mm and 200mm high (all internal sizes) so it easily takes the usual 400x300mm stackable trays.

I simply level the bottom tray within the propagator and take it from there.

One other thing I have done is tape up the vents on the lid – just to help keep dust out.

Is there somewhere I can send a photo of this amazing taped up, seed growing, doming curing, electrically heated plastic box? :lol1:

[Lee Jones]

Blimey, that was quick !

Thanks for the info, definately going to get one today, and give it a go.

Can you send the pic to my email

(thought I had allowed my email to be shown in the profile selection, obviosly not)

Thanks again for the help

It’s Good this ere site !

[Chris Wool]

over the years i have used several makes some build higher but flow out less and have always gone back to the mockridge resin which i think has a nice ballance – i like the gardening tips in the winter i use a spot light under the glass tray.

chris

[juddr]

I use a heating mat / pad brought from a garden store for raising seedlings… this way i can sit my tray of doming on top of this for the entire time till dry.

[Lee Jones]

Under normal conditions the resin will start to cure in approx. 2 hours and be fully cured in 24

So what benefit in terms of speed is obtained using heat, as outlined in the above two examples ?

[Rodney Gold]

the advantage of using heat is 2 fold BUT it depends on the type of resin you use. Epoxy resins GENERATE heat when gelling and heat can actually accelerate the gel process , which is good and bad – good in that it cures quicker , bad in that bubbles get trapped in the gel and dont release.
Ideally one needs a long pot life -IE how long its workable for after mixing and a short cure time , IE how long after its applied that it can be handled.
for Urethanes and to an extend epoxies is that there be NO MOISTURE when it cures. Polyurethanes are VERY susceptible to moisture and absorb it from the air , in cold conditions polymerization takes place slowly and the mixture absorbs water and when you come back 24 hrs later , the domed decal is a mass of foam or the dome is occluded with bubbles etc.
Using heat does 2 things 1) Dispels moisture and 2) Acclerates gel times from hours to minutes. Once the urethane has gelled (polymerised) it cannot absorb water at all and you can safely leave it to cure fully. We handle our domed stuff in 20 minutes. There is an alternative to doming with 2 part resins and that is doming with a UV curable resin which sets withing 10 seconds after being exposed to UV light , the problem is that its expensive and not very syrupy (viscous) so youur domes are generally thin. The UV light is also expensive and needs replacing (its not one of those disco type things , its the type that can give you skin cancer at 50 meters in 5 minutes)
In general , I find the resins marketed in england and USA pricey , we use a local product that sells here at about 8 quid for 400 ml in cartridges and is UV stable , mercury free and has wonderful adherence properties , debubbles easily has a long pot life and gels at 40 degrees fully in 20 mins , its also viscous enough to build quite a high dome. Even cheaper in 5 or 10 kg bulk packs (about 1/2)
Resins are generally toxic , always wear eye protection , gloves and protective clothing. If it gets into your eyes , you are in trouble!!!

[Mark Shipley]

Using the propagator technique I find that with the trays being already warmed, the polymer spreads quite readily and after 10 minutes just a very quick flame is all that is needed to de-bubble. Gelling happens very quickly after a further 5-10 minutes – I guess this is down to the prescence of the silica gel absorbing any moisture.

By the way Rodney, ever thought about shipping the 400ml cartidges to England?? 😉

[Lee Jones]

Rodney
As usual your explanation and advanced knowledge of this process is outstanding. I wondered why i was getting all this bubble effect in the cooler (damper) winter months, and yet in the summer the majority of everything we did was perfectly OK.

we are currently using Urethane from Interfax, although we have not had any problems with their resin, I would like to experiment with some other makes just to see the difference.

MrSticker, Where can I obtain the mockridge resin you mentioned, and can anyone else give me some other alternatives to try ?

[J. Hulme]

Mockridge international

http://www.mockridge.com

[Lee Jones]

quote outline:

Mockridge international

http://www.mockridge.com

[Mark Shipley]

You may also want to try Liquid Lens at – http://www.liquid-lens.co.uk

If you want high domes their product works a treat.

[Rodney Gold]

I went to that site , just see promo stuff and nothing on te resins , dosing systems etc?

[Lee Jones]

Same here — thought there was going to be a little more than that !

But thanks anyway

[Mark Shipley]

Hi Rodney,

Sorry, my mistake to view their dispensers, resin etc. visit their .com at

http://www.liquid-lens.com which takes you to ‘our’ side of things 😉

Mark

[Rodney Gold]

Ta , just as an aside , We built a dispenser out of a buggered drill press , a few broom sticks and a supawood housing , does almost the same thing as a 2000 cartridge quid dispensing system 😉
How much do they charge for their 400 ml carts ?

[Mark Shipley]

You will probably want to sit down first…

6x400ml £36 per unit, 18x400ml are £29.99 per unit

I have used both Mockridge and Liquid Lens and I prefer the Liquid Lens as it is a more viscous product and results in a ‘harder’ and higher finished dome. Also their mixing tubes do a far better job at mixing however the product is more suited to simple shapes than complex ones, Mockridge suits complex shapes better.

[Rodney Gold]

That is totally rediculous , price wise I mean. Even at 29 quid its a total rip off – these are standard industry carts , I even find R85 (R12 to the pound , IE 6 quid a cart) to be very expensive locally , we pay less than 15 quid for 5kgs here , about 4500 ml , less than 1/10th of the price!!!!

[Clive Martinez]

Rodney,
I would love to buy 5kg for 15 quid. I reckon even if the material was sent by courier it would still be a LOT cheaper.
Do you have a supplier who is willing to ship the stuff over ?

Regards
Clive

[Rodney Gold]

The company that developed is is called ANT composites in Cape town , there is a problem with sending it over as its classed as a hazardous substance and is subject to some serious material handling issues , evidently there are compounds called isocyanates in it. Its a flexible epoxy (means its easier to use than urethanes)and is developed from a Ciba Geigy water clear epoxy resin product and is most likely available overseas. You can easily get a urethane that is uv stable at much cheaper prices in England if you prepared to buy bulk. There is one issue however and that is shelf life , its about 4-6 months for both the urethanes and epoxies we use. (conservative however , we have used stuff up to 18 months old with no problems). You need containers that have nitrogen blankets for dispensing , this stops water abosrbtion etc.
The uretyhanes are 1:1 mixtures and the Epoxies are 100/60 mixtures. The epoxies yellow slighty over 18 months , they do not adhere to vinyl well , you can specify the hardness from glass hard to almost gels. We actually have an odd application for digitally printed vinyl and the very soft gell like epoxies. We cast onto the vinyl and the colour migrates into the epoxy , we then peel the vinyl backing off and are left with a clear hard jelly like dome with the image. This can be stuck to car windows etc , almost like a reuseable static cliing type. Doming makes us excellent money and along with my large format print and cut machine , we are making far more doing intricate die cut domed decals than we could ever make churning out X sq meters of banner etc.
We charge about 30 pence for 2-5000+ 2″ x 1/2″ decals. Total cost of materials only including resins is about 6 pence.