Page 1 of 1

bubblejet printing on plasticard!

Posted: Sat Oct 21, 2017 9:57 pm
by brit-in-bama
We all know by now that we cannot use a bubblejet printer to print on the plasticard we use to build our models, be it buildings or loco's or running stock, for two reasons,1 the ink will not dry, and 2 it reverts back to a liquid and the surface tension draws it back into little beads. So, how do we change this, for starters ink is a dye and is a mixture of a colorant, an alcohol base, and a water carrier, and the ink dries because the paper absorbs the water content of the ink, and that leaves the alcohol content to evaporate, thus it dries really quickly on paper. and without going into great forensic reasons, the water acts as an evaporation inhibitor for the alcohol, we can buy rubbing alcohol over here in different concentrations, 50%, 75% and 91%, the only difference is the water content, thus 50% dries (evaporates) slower than the 91% which takes only a couple of seconds. so I have been mulling over this for the past year or so, and have tried all sorts of things, spray painting primer, hairspray, thin water-based glue, thinned down wood glue, sugar solution, honey, all these beaded up before they dried, leaving a lumpy surface, and none of them accepted the ink on top.

so why am I writing this post, because I think I have found "a" solution, its not going to be the only one, but its the only one I have found that actually works, it needs refinement, but I dont have access to a chemical lab or money to explore other avenues, but hopefully this will point the way for others to experiment.

so what have I come up with, mat clear coat, and cornflour, (cornstarch over here in the USA) and its a relatively easy process, nothing out of the ordinary stuff everybody can find.

so here goes
I printed this image last night, you may recognize it :lol:
plastic printing 3.jpg

and as you can see the ink has beaded up and is still wet, as the smudges from the cotton bud show,
that was on the untreated half of this 20thou plasticard, I treated the other half (below) with the process, and the ink dried in less than a minute!! I know its not perfect, but it is dry and the lines came out better than expected, no spreading out or fuzziness, so if nothing else it is useful for line drawing or printing the outlines of parts to cut out.
treated half.jpg

first, all you will need to try this is masking tape, a can of matt spray, a sieve, and a cheap tub of cornstarch.

first clean the dull side of the plastic with alcohol to remove all the oil. then give it a light even coat of the matt spray, then before it even starts to dry sprinkle the cornflower with the sieve over the entire thing, I was a bit slow as my can was nearly empty, and I was taking photo's as well.

and then let it dry for an hour or so, then clean it off with a soft brush or soft cloth, and wipe it over and remove all the dust (dont want any in your printer), it should feel a bit like a rough paper, its now ready for printing on, not all printers like thick card, I have to help mine to start with a little pressure on the card as it starts to feed, but after it catches it in the rollers it prints just fine.
so what to do if it fails, or you did a mistake, without loosing the card, quite simple really, wipe it over with mineral spirits and a bit of rubbing with a few paper towels, and remove everything and start again!
plastic printing 5.jpg

I know this process is just a start, but it works.

Re: bubblejet printing on plasticard!

Posted: Sat Oct 21, 2017 10:02 pm
by brit-in-bama
any questions or comments would be welcomed,

Re: bubblejet printing on plasticard!

Posted: Sat Oct 21, 2017 10:46 pm
by Ironduke
I wonder what they use to make inkjet printable overhead projector transparency film?

Re: bubblejet printing on plasticard!

Posted: Sat Oct 21, 2017 10:53 pm
by brit-in-bama
Ironduke wrote:I wonder what they use to make inkjet printable overhead projector transparency film?
its a fine coat of glue of some kind, I have some, and used it, but its not smooth, and its slightly tacky to the touch, but what its made of I have no idea! (I wish I did), perhaps someone on this site knows, or better yet, knows where we can get some!

Re: bubblejet printing on plasticard!

Posted: Sat Oct 21, 2017 11:00 pm
by TimberSurf
Overhead projector transparency film has some sort of clear matt coating on one side. I would guess something like IPA or thinners that slightly melts the surface as an immediate precoat might work. Or "open" the surface with fine sand blasting (soda).
My first experiment would be with an artists "matte", like modge podge matt.

Re: bubblejet printing on plasticard!

Posted: Sat Oct 21, 2017 11:08 pm
by brit-in-bama
tried mod podge first of all, it didnt do squat! then I tried gesso that artist use on canvas so they can re-use it, both act as a barrier to the ink, and it was the bubblejet printable transparencies that started this quest, and my first choice was powdered chalk, but I didnt and dont have any, and the particle size is very random, whereas cornflower is pretty much uniform at 1 micron in diameter, its about as fine a dust as you will find at home, and it absorbs the water in the ink so it can dry in its normal fashion.

Re: bubblejet printing on plasticard!

Posted: Sat Oct 21, 2017 11:35 pm
by Bufferstop
I was told (by a paper salesman) that it was liquid starch sprayed onto the final roller in the thicknessing operation. I haven't seen the process used in production so if it's correct or not I have no idea. All I know is the samples I've tried you can't remove the coating without dissolving much of the surface of the sheet.
Have you tried the thermal offset process? Used for printing images onto clothing etc. You print a reversed image onto a special "transfer paper" and then transfer it to the required surface by pressing it in with a domestic iron. The process works best with colour laser prints rather than inkjet.

Re: bubblejet printing on plasticard!

Posted: Sun Oct 22, 2017 12:03 am
by brit-in-bama
the main problem is that styrene melts at 425*f, and liquefies at 475* so I was trying to do a cold process, as a domestic iron melts styrene sheet for fun, and so far all the sprays and paints I have found are either acrylic or oil based, neither will absorb the ink, so my next thought was something to use as a binder to make an absorber stick to the sheet, hence the search for a very thin glue to stick a very small water absorbent particle to the sheet, that is either permanent or removable with the right chemical, liquid spray starch would be good if it actually stuck to the plastic, but it doesnt, it needs a binder of some kind, and if the binder coats all the particle as it would if mixed to form a spray coat that would stick to the sheet, it will be totally sealed and no longer absorb the water, the idea behind using cornstarch was that the only part of the particle that is sealed is stuck to the binder, thus leaving the other side un-coated so it can absorb the water, and so far this is the only thing that actually works, next I will try some powdered chalk, but it may be a while before that happens.
I have just had another look at my coated bubblejet transparencies, and they are still slightly tacky to the touch, and they are at least 5 years old, but in their original bag, so there has to be some kind of glue that holds whatever they use, could be a very fine spray or as you say a fine coat pressed into the glue so it becomes invisible to the eye, I dont know, but for now I can use this process, may not be perfect, but it does work.