Discuss the various aspects of heat press technology. Transfer paper, inks, plastisol transfers, vinyl cutters, printers, commercial usage, durability, suppliers, etc.
We recently switched over to the SoftJet light transfer paper. Lots of good things about it, just as we expected from the forums. There is a dark side (pardon the pun) for us. On some brands of whte tees and on all of our canvas totes, we are getting significant yellowing of the cloth. The temperature of 375 degrees coupled with the longer dwell time of 30 seconds seems to be too much for many of our products.
This problem eventually kept us from using Duracotton HT. We liked the product, but the transfer temperature was just too high for many items.
We have tried several supliers for natural colored canvas totes. There is some variation, but all showed objectionable yellowing with SoftJet.
We've done all the normal things. Our temperature really is within a few degrees of 375.
Has anyone found a way around this prblem or a tote supplier that does not yellow at these temperatures.
I normally use a teflon sheet on everything I press. I sometimes use a silicon impregnated paper sheet (usually for plastisol transfers because the teflon is so staticy and tend to lift the letters when I place it) I tried both on the totes and still got the scorching.
I haven't tried the Toppers tote that Lou recommends. I plan to bring some in next time I order. I'll post results.
if you're getting yellowing even thru the teflon it sounds more like the fabric has been treated with sizing or something similar than an actual fabric scorching issue....
__________________
it's not what you gather, but what you scatter that tells what kind of life you have lived!
It may well be the treatment, but not actually the sizing. Cotton cloth and paper used to be sized (made water resistant) by adding a rosin based material that repels water. To get the rosin to set or stay on the fibers, they added aluminum sulfate (alum) to the treatment. The alum worked best on the acid side, so the pH was dropped to 4.2 to 4.7. When the cotton fibers age, the acid causes reactions that lead to yellowing. This is why newspaper turn yellow when they get old. Archival paper is made with a different process that keeps the pH above 7.0 or neutral. Books printed on this paper do not get brittle or yellow with age, at least not as fast.
The alum/rosin system is cheaper, so you find it used on many of the lower cost, imported canvas bags. It has not generally been a problem for us, but the longer dwell time with the new transfer paper has increased the amount of yellowing.
I've actually pressed the Toppers 806 canvas bag with JPSS without a problem. HOWEVER, I did not press for the full 30 seconds -- it just wasn't necessary to make it work -- I believe I pressed for 15 seconds, and it worked GREAT. To verify this, you can go to the Transfer Paper Testing thread, my detailed post about the totebag material is there with pics
In regard to other shirts getting scorched at 375 for 30 seconds, I find that hard to believe, actually. I press that regularly with the JPSS on Gildan, Jerzees, Hanes shirts of different materials: 100% cotton & 50/50 without a problem. In fact, I press mousepads at 390 for over 30 seconds without a problem...
Are you sure that your press REALLY is at 375? Maybe you could get a laser gun and check it? I understand these can be bought for a cheap price at Harbor Freight.
I don't think I'm off more than a few degrees on temperature. I checked with an IR gun and with a thermocouple, surface contact pyrometer. Both are only accurate to +/- 3 or 4 degrees, but I was just about on the set-point.
I also press mouse pads supplied by Coastal Business. Have not seen any discoloration problem with them.
Tees I use are mostly Gildan and Port Authority. The yellowing is not severe on the tees, but it is visible.
We now use only the teflon sheet on whites. With other transfer paper, we often used silicon treated kraft paper available through Stahls. This has less static than Teflon and was easier to use on pre printed plastisol letters and numbers. Shirt yellowing is worse with the paper, hence only teflon now.
The totes were the biggest problem. I didn't try reducing the time that far. That might help.
have you tried pressing multiple times for less time i.e, pressing twice at 15-20 seconds. i do this on some of my shirts and it did away with the yellowing from the heat. just give it a quick cooldown in between...... 10-20 secs.
Thanks for the reference. I had not seen the other post. Peroxide is a bleach, so I can understand the effect on yellowing. It wasn't clear if she masked the design or misted the whole shirt. I'd be afraid of bleaching out the design. I plan to experiment and find out
Thanks for the reference. I had not seen the other post. Peroxide is a bleach, so I can understand the effect on yellowing. It wasn't clear if she masked the design or misted the whole shirt. I'd be afraid of bleaching out the design. I plan to experiment and find out
Jim
I would say she misted around the image since the yellowing is not apparent in the printed area. Besides it would take a lot of soaking time and exposure to bleach the image. The peroxide solution is pressed and steamed of immediately off the shirt. To eliminate the guess work you have to try it yourself. You still have the discolored shirt don't you? Try it on that shirt .
__________________
Luis CorelDRAW macro author Macro Website
Garment Discoloration 
CorelDRAW macro author
