Need to Register?

Sunro · April 18th, 2008

My very first (possibly dumb) question in this forum . . . sorry, I'm a DTG newbie

After a few initial hiccups, our new BlazerPro has been producing really nice results, especially on dark shirts, but we've hit a problem which we can't seem to resolve experimentally ...

The washability of red colors, especially strong reds, seems significantly reduced when printed over a white underbase on a pre-treated shirt. It is evident not only when printing red itself, but also when printing true gray scale (where the R, G and B values are identical). The colors are fine straight out of the heat press.

However, in every case, after the first laundering, the red seems to have been partially washed away. This means a "faded" look to reds over the white underbase, or gray turning a bluish-green because it has lost some of the magenta in the mixture. This does not occur on white or very light shirts which have not had pre-treatment or an underbase layer applied.

Is washability of the magenta Fast-3 ink a known problem?

I would have thought that if FastRIP detected it was to produce pure gray scale it would simply use a mix of white and black, but apparently it uses a mix of CMY (and maybe K) instead. Perhaps it's simply the only way it can be done, but if magenta ink exhibits a washability problem then durable grays are an issue.

We have tried several combinations of pre-treatment amounts and heat press temperatures/pressures/times, but in every case the result is the same. Printing is done with one 1440x720 underbase and one or two 1440x720 color layers.

Are we missing something obvious or doing something dumb?

Suggestions or comments gratefully received!
Chuck

sunnydayz · April 18th, 2008

Hi Chuck

It sounds like you may not be curing the ink long enough. What temp and time and you curing at. It seems this may be a problem as you are only having this issue with the dark shirts. Are you changing your cure times to longer on darks ? also what might work better than single pass 1440 is printing double pass 720. cure time should be at 330F for 3 minutes with the dupont ink. It sounds more like it is a curing issue than a printing issue. What are you using on top of your shirt when you cure? are you using silicone treated parchment or a teflon sheet? If you give this info It might help to answer more accurately.

Sunro · April 18th, 2008

Hi BobbyLee! Thanks for the rapid posting

We have been experimenting with various temperatures and curing times. The latest suggestion from the US Screen support folks is to try two 180-second cures spaced about 10 seconds apart, to prevent scorching. We are using a 338F temperature at the moment (on the rash assumption the Hix SwingMan is accurate). This is based on a forum thread which suggests this to be the optimum temperature for DuPont inks. James is doing a test as I write this. We usually adjust the amount of pre-treatment according to the "darkness" of the shirt color, black getting the most.

We use a non-siliconized parchment for pre-treatment drying, and a teflon sheet for curing, and we have the heat press adjusted for what we think should be "medium" pressure, whatever that really means. Too bad there isn't an accurate way for measuring pressure.

The issue of accurate grays is tricky, because FastArtist/FastRIP normally has to blend CMYK inks, not simply black+white. US Screen has suggested an interesting workaround for our particular case, where we are printing only white and dark gray on a medium gray shirt. It involves manipulating FastArtist's method of creating shades of gray, in order to eliminate the slight bluish cast we see before washing.

Your suggestion regarding print resolution vs. number of passes is interesting .. something we'll definitely try.

I have to comment on US Screen and the BlazerPro ... as an engineer and someone new to the DTG thing, I am very impressed with the way in which the printer is designed mechanically. As a programmer and computer weenie, I also have to express my satisfaction with the way the US Screen support folks have treated us. No complaints there.

Cheers!
Chuck

sunnydayz · April 18th, 2008

I am glad to hear us screen is taking care of you well

on another note Wow that is along cure time hmmmm if you are curing 180 x 2 that comes to 6 minutes you are curing your ink and seems too long to me. I have been printing getting close to a year, I have an HM1 and I have never had to cure that long. 3 minutes should be good maybe 3 1/2 at the most but 6 is alot. Maybe just maybe the amount of time your are curing is too much and degrading the ink a bit from too much heat. Also 338 is a bit high on the temp, most recommend 325 to 330 to be the optimum heat. I am not sure if it is possible but maybe your over curing a bit too much. I have not heard of anyone curing for that amount of time, but if someone here is I am sure they will chime in

Also most of the dtg printers out there will use cmyk mix for grays and not black and white mixed, its the way the rips process the colors. At one time I was even trying to get my printer to print grays with just black and white as I too was getting a blue tinge to my grays but the machines make gray with the mix of cmyk when it rips. I dont know if your rip has an color adjustment in it but you can always try reducing the cyan a little in the ink configuration and see if this helps with getting better grays.

Are you using teflon sheet or silicone parchment for on top of the ink when curing. I found that with the teflon sheets it tends to not cure as great in the center of an image due to steam having a harder time escaping the solid surface of the teflon, where as with the silicone parchment paper it is much easier for the steam to escape from the fabric. Also when I press I use the least amount of pressure at all, with too much pressure it also causes the issue of the steam not being able to escape while curing. Are you still seeing steam coming off of the garment at the end of that long cure? Let me know if any of this helps

zhenjie · April 19th, 2008

Magenta has always been an issue with me. I've done test where I've printed C Y M K seperately on the same t-shirt and washed it. The magenta clearly washed showed signs of washing out and exposing the white and sometimes yellowish underbase (Since its mixed with yellow). I've emailed DTG with my concern but they dont have any solid answers. I know one of their distributors had been battling the same issues.

I think its a matter of two things.

Firstly, the magenta does not bond as well onto the white ink as the other colors
Secondly, when washout does occur (and it would on most colors), red is the most noticeable because the white/yellow that peeps through really contrast with the red color.

I had hoped dupont could resolve my issues. But they dont seem to have so I'm moving to DTGInks once my Dupont is used.

Gunslinger · April 20th, 2008

Bobbielee is correct, you are wayyy over curing. I dunno who at USScreen (I have been running a T-Jet 3 for a year) recommended curing a t-shirt twice, but that is the strangest thing I have ever heard. Simply put, you cannot cure anything more than once. The only thing that will accomplish is burning or scorching your cured inks, which can happen if your press is too hot or curing too long. You should be noticing the discoloration of your prints right out of the press, and before you wash the garment.

Press at 330-335 for 3 minutes for dark shirts requiring an underbase.

If you are still having problems with washability, and you are pre-treating (search the forums for the latest pretreating methods that are working better than manufacture instructions) and curing correctly, it may simply be the detergent you are using. I had a scare last year with the blues in my print were washing out badly, and it ended up being our fancy, dancy heavy duty washing machine causing the problem. The recommended detergent and extra high spin cycles (to reduce dryer times) were beating up my prints. After changing to normal detergent and average spin cycles, the problem was eliminated.

cavedave · April 21st, 2008

You can print grey / black as pure black ink (there are several ways to do this with FASTRIP). But with all CMYK color printing grey is made up of CMY+K (this is true from newspapers, magazines and all Inkjets).
The reason is very simple, print
100%CMYK and then print 100%K, you will see that the CMYK produces a much darker (and richer black).

Now think about a photo with lots of shadow area, some of these shadows will be dark blue or green (have some coler hue) and therefore you must print these as CMYK.
If you print with just K for all your pure greys, your color images would look really bad, because you would have this giant contrast change between areas that are CMYK shadows and just K shadows.

So that is why grey is made up of CMY+K.

Balancing grey is always a bit trickey, but more so than with most printing with the DTG market. This is partly due to the different textiles used and other factors such as envoirement, and shear ink volumes that have to be printed.

Best regards

-David

Sunro · April 21st, 2008

Many thanks to all of you for the great replies!

James and I both agree that the double cure seems a bit drastic. Fortunately we haven't noticed any scorching, so it's possible the heat press temperature is not displaying correctly. I'll try to find some of those paper-strip temperature calibration things, which I'm told are more accurate than most digital probe or infrared thermometers (unless you pay a fortune).

Here are some results we've gotten over the weekend ...

1) Thanks to BobbyLee's suggestion, we switched from teflon to siliconized parchment for curing shirts which have had pre-treatment and/or underbase applied. What a difference! Better steam escape seems to be the reason. The washability improved significantly and the plastic-y shine of the ink surface was reduced quite a bit.

2) We cut back on the curing time and set the temperature to 330F, and curing still seems fine. More tests tomorrow. The odd suggestion from US Screen was actually something one of their customers had done with good results. The support guy sounded a bit skeptical too.

3) We did try messing with FastRIP's grayscale stuff, but in the end we let it do its own thing. Because the washability of the magenta ink seems to have improved a bit (but not as much as we would like), we have become less concerned about the initial bluish cast to grays. However there is still a shift to bluish-green after washing

The explanation of why CMYK is used to generate gray makes good sense to me now that I've thought about it a bit. Color science is not always easy to understand, and the human eye's sensitivity to colors is a bit tricky. I have come to understand that the eye is much more sensitive to color variations in some parts of the spectrum, which perhaps explains why the bluish cast on gray is noticeable.

Regarding the wash cycle, we use a front-loading tumble washer, warm water, a bit of Costco concentrated detergent powder, and warm tumble dry. The German machines do spin at a rather high speed, but slowing it down has made no difference. The shirts are turned inside out for washing. We have tried Oxy-clean additive to see if that creates a problem, but it seems to have no effect one way or the other. Actually, we have also tested washability by breaking all of the laundry rules (which most customers will probably do anyway) and there doesn't seem to be much difference.

Thanks again to everyone! It's great to be able to consult with others who are "paying their dues" in this rapidly emerging business.

Chuck

Sunro · April 25th, 2008

Hi again Folks,

Just a bit more information regarding the washability issues ... we seem to have gotten over the hump with this, and things are looking much better now.

We have settled on a bit longer cure than recommended for colored shirts which have pre-treatment and underbase applied: 330F temperature and 250 seconds curing time.

For white shirts, which we normally don't pre-treat, we use the same temperature but reduce the curing time to 180 seconds. We have not tried the pre-treatment designed for light shirts (FastBrite) ... does anyone have comments about it?

The magenta still washes out a tiny bit, and if you look carefully there is a slight bluish cast to grays (especially dark grays), but the visual effect is minimal, and you'd probably miss it if you were not looking for it. The perception of color shift is also affected by the color of the shirt, of course.

We purchased a few paper temperature calibration strips and found that our Hix SwingMan's setting is fairly accurate.

The US Screen support team has been really good about offering advice and patiently walking us thru some suggested solutions. Our thanks to them!

The biggest change (and the most satisfying) was the switch from a teflon curing sheet to siliconized parchment. I wish we had thought of that long ago, but it's all part of the learning process.

Now we are experimenting with parchment supplies from local dealers at significantly lower prices than the printer dealers. Siliconized parchment (for curing the inks) can be bought in rolls from baking supply stores, and rough-surface non-siliconized parchment (for drying the pre-treatment) can be found at art supply stores.

Our next adventure will be printing on surfaces like metals, glass, and ceramic. We are starting to experiment with new digital ground coatings from Golden and InkAid. We'll probably make lots of mistakes, but we'll have fun making them, maybe

Chuck

equipmentzone · April 25th, 2008

Just wanted to point out that the pretreatment for white and light colored shirts is FastCOLOR, not FastBright.

FastBright is used when printing white ink on light colored garments.

Harry

sunnydayz · April 25th, 2008

Hi Chuck, Here is a link for silicone treated parcment that is a really good price. This is where I buy mine from Matfer Bourgeat EXOPAP - Parchment Paper , this is for the 15 3/4 x 23 5/8 size which is perfect for the bigger heatpresses. Hope this helps some

Sunro · April 25th, 2008

Quote:

Originally Posted by equipmentzone


	Just wanted to point out that the pretreatment for white and light colored shirts is FastCOLOR, not FastBright. FastBright is used when printing white ink on light colored garments. Harry

Ooops! Thanks Harry! Another education point. FastColor is new to me, not one of the items in the kit which came with the printer in January. What we have here is FastBrite and Pretreatment #1 (in the bottle with the black label). How is FastColor different from either of these? It would seem I'm a bit behind the times already

Sunro · April 25th, 2008

Quote:

Originally Posted by sunnydayz


	..... Matfer Bourgeat EXOPAP - Parchment Paper , this is for the 15 3/4 x 23 5/8 size which is perfect for the bigger heat presses.

Thanks BobbieLee! We got a roll of Baker's Mate parchment, 15 inches wide x 10 Yards long (giving us about 18 sheets) for $4.00 retail, which isn't cheap but is low-risk for purposes of experimentation. Your suggestion is very inexpensive (less than half the price charged by printer manufacturers).

Chuck

sunnydayz · April 25th, 2008

Also Chuck, Harry is right the fast color works fantastic for lights. It really keeps the colors vibrant and the washability is so much better with it.

Need to Register?

Resources

T-Shirt Sites

Washability of magenta Fast-3 over white underbase