DSF

I am subbing images onto glass coasters. the nice, square ones from TTP. The black in my design is coming out brown, making the whole thing look faded. My first four of this batch have come out this way and I don't want to waste any more. I have subbed several sets of coasters before now mostly with good success, but also with this brown problem. I can't work out the logic of it. Is the press not hot enough? Too hot? Do I need to warm it up closed instead of open so the bottom platen is hot too? do I put the coaster on top of the paper instead of the paper on top of the coaster? Trouble is, it has worked fine before. 4 mins at 200degrees medium pressure, paper on top . . .
I have a feeling it cured itself over time when it happened before, but I couldn't swear to it. It only happens on glass coasters, unisub ones are fine.
Any one have any clues? Pisquee? you use these i think. This is an expensive problem, and this is for a buyer. . .
thanks in advance, Jon

Paper on base of press, with design face up, coaster white side face down is how we do them (and have done 1000s this way)
They are toughened glass, so pretty hard to smash - we've used light and heavy pressure, making no difference.
We used to use the ones from TTP, but have since moved to the ones Longforte have (which appear to be the same manufacturer as the ones BMS also now have) they're a lot cheaper - the colours aren't quite as good, but there are less bad coasters (less which are scratched, cut badly, or don't print properly) and they come in white unprinted boxes which hold 4.

PS/E2A - you should change the title of your thread, as it doesn't give any clue what the thread is actually about

JBDesign;91468 wrote:I am subbing images onto glass coasters. the nice, square ones from TTP. The black in my design is coming out brown, making the whole thing look faded. My first four of this batch have come out this way and I don't want to waste any more. I have subbed several sets of coasters before now mostly with good success, but also with this brown problem. I can't work out the logic of it. Is the press not hot enough? Too hot? Do I need to warm it up closed instead of open so the bottom platen is hot too? do I put the coaster on top of the paper instead of the paper on top of the coaster? Trouble is, it has worked fine before. 4 mins at 200degrees medium pressure, paper on top . . .
I have a feeling it cured itself over time when it happened before, but I couldn't swear to it. It only happens on glass coasters, unisub ones are fine.
Any one have any clues? Pisquee? you use these i think. This is an expensive problem, and this is for a buyer. . .
thanks in advance, Jon

Blacks going to brown is caused by too much heat for too long. Take one glass coaster and print a block of black. Cut this into small squares so you can get say 4 or 6 on a coaster. Place one in a corner and press for 190c 4 minutes, try another in a spare space at 190c 3 minutes and so on. At what temp/ time combination gives you the best black? Whilst your press may say 200 or 190 on the display it may be slightly different at the heat platen so this will help you find the optimum combination for your machine on glass. As several members here will also do - write this combination down so you have the correct settings for that substrate in the future. Glass, hardboard, metals etc will all have sightly different combinations for your optimum images.

Thanks for the swift replies. Much appreciated. I will do the glass on top way, thanks Pisquee, and do a trial as suggested with different times and temps.
Glad to know it's something logical. Too hot and too long.
bless ya
How do I change the subject line in a thread?
Jon

3 minutes at 180 degrees!
many thanks again,
Jon

JBDesign;91474 wrote:3 minutes at 180 degrees!
many thanks again,
Jon

Excellent. Job done

JBDesign;91474 wrote:3 minutes at 180 degrees!
many thanks again,
Jon

BMS: Recommended pressing temp 180-190 degrees for 2 minutes. Longforte 200 degrees for 4 minutes for the same coaster!

When doing full production (from November onwards) we'll print off sheets of 12 designs (3x4) and put them on the press bed, and lay the 12 coasters on top - This way 12 coasters in 4 mins is equivalent of approx 20 seconds each, in that 4 mins you can get the next 12 put of their wrapping... this way you're printing 180 an hour.

s for temp/time, we've always done them (both TTP and Longforte/BMS) at 200°C for 4 mins on PressMech presses, and with InkTec inks -wondering if BMS' temp/times are for Sawgrass/Ricoh inks?

TTP site said 4 mins 200 degrees at medium pressure.
Didn't know BMS did these coasters, I knew about Longforte doing them, but when I looked a couple of months ago they were out of stock, and they didn't supply the plastic feet. I know you can get them online, what do they call them? Bumpers or something?

I am using Sawgrass/Ricoh combo so that may be what made the difference in my case (3 mins at 180). Didn't know that was an issue, until now. . . Lot to learn, me.

Longforte's do come with bumpons, and white boxes which hold four coasters, and come in boxes of 120, rather than 48 that TTPs do ... them being out of stock was our fault, sorry!