Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes?
For a long time we've suffered on-and-off with the problem of the 'hair' effect after pretreating black shirts.
Is there something I'm doing wrong in this workflow?:
heatpress shirt for 10 seconds @ 340F
spray print area with pretreat (from approx. 20cm away) with Wagner sprayer, covering each area from left to right three or four times so area just begins to 'glisten'
heatpress shirt for another 10 secs @ 340F
print shirt whitebase
print shirt colour layer
heatpress shirt for 2 minutes @ 340F
Sometimes this can result in a perfect shirt, sometimes you get tiny little 'hairs' of fabric cotton rising up through the print and even through the colour layer, which ruins the print. You can even see the hairs of fabric rising almost immediately after the whitebase is printed.
Is this a result of using too little or too much pretreat, or is it due to some of the fabric pile being pulled away by the PTFE teflon sheet? Is it just due to the pretreat sticking to the teflon sheets and I'm not cleaning them often enough? It seems mad that I can get such variation in the quality of heatpress, pretreat and print, even across the same batch of T-shirts.
I regularly clean the sheets to make sure they're not gummed up with pretreat residue, and I've also used alternate sides of the sheet during pressing to try and separate the 'sticky' steps from the final pressing steps.
All protips on avoiding these kinds of problems are greatly appreciated! It's making me apprehensive to print on black or dark coloured shirts, because I work in fear of the problem happening again. Half the time I end up wasting good shirts and ink trying to stop this from happening again and again (seemingly without warning sometimes!)
Re: Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes?
DO you have a dwell between the white and color passes? You can take a piece of parchment and a foam roller and roll the white (pressing the fibers down into the shirt and ink) before the color pass.
Or if the dwell is long enough even take a hot iron to the white before the color pass. Using a piece of parchment of course.
These have worked for me. Some brands of shirt just seem to do it more than others. You can even try switching t-shirt brands.
Re: Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes?
Quote:
Originally Posted by Tj Ryonet Tech
DO you have a dwell between the white and color passes? You can take a piece of parchment and a foam roller and roll the white (pressing the fibers down into the shirt and ink) before the color pass.
Or if the dwell is long enough even take a hot iron to the white before the color pass. Using a piece of parchment of course.
These have worked for me. Some brands of shirt just seem to do it more than others. You can even try switching t-shirt brands.
If by dwell you mean a pause before printing the colour pass, the HM1 waits for me to reset the head back to Ready position before printing the colour layer, so I suppose to dwell period could be as long as required! I usually wait until I can see the ink begin to set (it starts to set fairly quickly) - but I can see the hairs raised almost as soon as the head has passed over an area during the whitebase stage. Just doing it as we were shown in our training ... but of course it's a bit like a dark art, T-shirt printing, no matter what you're told during training!
We've tried various brands of shirt, including Gildan, our own in-house brand (moderate weight) and FoTL. All are 100% cotton. I use slightly higher pressure for black/dark colour shirts than for white/light colour shirts - I've tried with a lighter pressure on black shirts but I noticed that I got 'beading' of ink towards the edges of the shirt, where the colour and white looked like it was trying to escape and smearing all over the shirt! VERY odd effect. Waste of a good print so I've not tried to replicate it
Perhaps what bugs me almost as much is the inconsistency in laydown of whitebase. Sometimes it can be absolutely spot on, solid with no patchiness or thread visible, and sometimes it's spotty and uneven. Is less more with pretreat, or is it 'better to be looking at it than looking for it?'
Re: Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes?
Quote:
Originally Posted by christopherw
Perhaps what bugs me almost as much is the inconsistency in laydown of whitebase. Sometimes it can be absolutely spot on, solid with no patchiness or thread visible, and sometimes it's spotty and uneven. Is less more with pretreat, or is it 'better to be looking at it than looking for it?'
After 3 years in DTG this still bugs the hell out of me. Doing pretreatment by hand is just far to inconsistent especially if the t-shirt brand you are using is bad to being with. I suspect its the t-shirt material you are using combined with inconsistent pretreatment.
Ways to minimize I've found.
Use teflon or non-silicone paper to cure the pretreat.
Cure the pretreat for 20seconds at least. Then open it, then close it down again for 5 seconds. This should help flatten out some more fibres.
You could also try brushing the pretreatment down into the fibres after spraying, that will help flatten some as well.
Re: Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes?
Quote:
Originally Posted by zhenjie
After 3 years in DTG this still bugs the hell out of me. Doing pretreatment by hand is just far to inconsistent especially if the t-shirt brand you are using is bad to being with. I suspect its the t-shirt material you are using combined with inconsistent pretreatment.
Ways to minimize I've found.
Use teflon or non-silicone paper to cure the pretreat.
Cure the pretreat for 20seconds at least. Then open it, then close it down again for 5 seconds. This should help flatten out some more fibres.
You could also try brushing the pretreatment down into the fibres after spraying, that will help flatten some as well.
Interesting, I've been experimenting with pressing before and after pretreating and I now do it as regular behaviour (in an attempt to flatten the fibres!) but maybe I'm not doing it enough.
I pretreat both before and after spraying as the last engineer I spoke to highlighted the importance for the pretreat to sit on top of the cotton, not be absorbed into the fibres - which is why ringspun cotton is preferable, apparently. So, based on that advice, I've been trying to get the pretreat to not just disappear into the shirt - but should I not be afraid of giving a shirt a good soaking with pretreat if the weave requires it?
Given the unreliable nature of manual pretreating, do you think the DTG pretreat machine (looks like the HM1's bastard child) is worth investing in, if only for a guaranteed even layer of pretreat? (not considering the more exact spraying area and less wastage)
The pressure question is a tricky one. I've been experimenting with pressures for a long time - using less pressure on white shirts and shirts with no whitebase than black shirts. Unfortunately I've not had the chance to conduct truly scientific tests yet... I'd love to experiment with printing the same image with whitebase on many T-shirts, altering the heatpress pressure each time. Problem is you can get in to so many permutations (pretreat technique, pretreat curing pressure and time, post-print pressing temp & pressure) it's almost overwhelming before you even start!
Re: Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes?
We use the Viper pretreater, for our pretreatment on dark garments.Then we use heavy pressure @365 degrees for 36 seconds on our transfer press to cure the pretreatment and to flatten down the fibers. After we print the image we use lighter pressure to cure the ink.
Re: Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes?
That's very specific timings Scott you use the same pressure for both blacks and dark colours?
I remember we looked long and hard at the Brother when we first got into DTG, but at that time they didn't have the ability to print on white (they introduced it about six months after we got our kit iirc).
Re: Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes?
Yes, We use the same pressure on all the colors we pretreat. The first few shirts we sampled we tried lighter pressure and we also got fibers popping up. With the heavy pressure it helps mash the fibers down.
Re: Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes?
I think I have some more testing to do next week, particularly as I have this order of black shirts to print my nemesis approaches!
How much pretreat does the Viper lay down as opposed to a Wagner manual spray? (can it be compared to 'x amount of passes at y seconds per pass'?) I've seen a vid of it in operation on the SWF East site, but not had a chance to observe it (and how much it lays down on the shirt) first hand.
Re: Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes?
An important thing to keep in mind is there is a big difference between using Brother pretreatment and Dupont pretreatment (what the Epson-based dtg printers use). They are not the same solution and thus have difference characteristics that can lead to a different method of pretreating.
Re: Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes?
Quote:
Originally Posted by christopherw
I think I have some more testing to do next week, particularly as I have this order of black shirts to print my nemesis approaches!
How much pretreat does the Viper lay down as opposed to a Wagner manual spray? (can it be compared to 'x amount of passes at y seconds per pass'?) I've seen a vid of it in operation on the SWF East site, but not had a chance to observe it (and how much it lays down on the shirt) first hand.
Their are two 'Vipers' used in the DTG industry and I think you're a bit confused by it. Viper XPT is the Pretreatment unit from USA, made for pretreatment only. DTG Viper is DTG printing machine made by DTG and isn't a pretreatment machine.
Re the DTG pretreatment machine. It will probably lay down a more consistent pretreatment but that machine is wayyyy to slow for an 'automatic' pretreatment machine.
Re: Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes?
Quote:
Originally Posted by zhenjie
Their are two 'Vipers' used in the DTG industry and I think you're a bit confused by it. Viper XPT is the Pretreatment unit from USA, made for pretreatment only. DTG Viper is DTG printing machine made by DTG and isn't a pretreatment machine.
Re the DTG pretreatment machine. It will probably lay down a more consistent pretreatment but that machine is wayyyy to slow for an 'automatic' pretreatment machine.
Totally! In the video I saw of it, it looked UTTERLY slow... When are they going to develop a wider print head or put two/three side by side for quicker passes?
Indeed I was confused with the 'Viper' brands; I was referring to the DTG machine but couldn't remember its DTG brand name (and couldn't be arsed to go look it up again )
Anybody know of a good guideline video (if you could say such a thing) for manual spray-based pretreating? Aside from trial-and-error everybody says different things :/
This is a discussion about Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes? that was posted in the DTG Pretreatment section of the forums.
Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes? 
... but of course it's a bit like a dark art, T-shirt printing, no matter what you're told during training!
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my nemesis approaches! 
Re: Raised fabric visible in print after pretreat & whitebase (dark shirts). Causes? 
