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Discussion Starter · #1 ·
Hi I was wondering if anyone would be able to assist me with some questions regarding my screen printing.

This is my set up:
  • I am printing on a heavy weight 100% cotton canvas, in a ‘natural’ calico colour (420gsm). Once the fabric is printed I cut out my pattern pieces and heat set the pattern pieces.
  • I am using Permaset Supercover Black with a 77T and 43T meshes (77T for bitmap work, 43T for larger line work)
  • I diluted the permaset ink with 5% cold water from the tap so it could run through the screen a lot better and get the consistency I needed to achieve the detail in my prints. I thoroughly mixed the ink after precisely adding 5% to a small batch of ink.
  • I left all my prints to air dry for 24 hours, laid flat on a table.
  • I have heat set some of these prints (test prints) using a heat press.

So far the best outcome for heat setting on the press has been the press set as @ 180’c and I:
- Hover 2cm above the print for 30 secs
Then with baking parchment on the underneath and on top of the fabric:
  • X2 30 seconds on front, letting the steam escape each time for 15 seconds
  • X2 30 seconds on back, leaving the press open for 15 seconds after each time
  • X2 60 seconds on front, leaving the press open for 15 seconds after each time

This may sound like over kill but quickness is not a large priority for me as the garments I make are very small runs. This combination has also given me the best wash, rub and scratch results out of all the different time and temp configurations I have tested so far.

There is no fading or wash out after numerous washes on an 30’c wash in the washing machine. However I do have some questions!

My questions are:
(1) Is it normal to have some surface rub off to a degree, when you rub the print when dry with a dry cloth or cotton bud with Permaset Supercover? I understand when wet, there will always be some transfer if you rub and or scratch the print, as rub and scratch test results are always worse when the garment is wet. I just wanted to find out if it is normal to have some ink transfer when rubbed fairly firmly, when dry? As I cannot seem to find this information or anyone talking about this anywhere and would love to know if it is normal. It has been driving my crazy not knowing! As obviously I am printing on cotton canvas so there is limitation to the temperature due to scorching and 180’c is the max I can go to, even two ‘c higher it starts to scorch in small areas.

(2) Permaset say you can dilute Permaset inks up to 5% if needed, which I thoroughly read about before doing and this is what I diluted my Supercover by. I just wanted to know if by adding this 5% water I could have affected the successfulness of heat setting? If it is not normal to have some rub off (as mentioned in Q1) would adding this 5% water have caused the print not to properly set?

Many thanks for any help, its so hard to find answers to such specific questions but hopefully someone may be able to shed some light on this and either put my mind at rest or finally clarify that there is an error somewhere in the process.
 

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That is a higher cure temp than I would aim for. A heat press directly imparts the heat through conduction, so the temp you set is pretty much the temp you get on the ink and fabric, unlike with radiant heat sources. 320F is the highest temp mentioned on the ink tub. I use 340F for one minute. 356F (180C) is potentially high enough to damage the ink.

I add a bit of water to mine as needed to maintain the original feel of the ink, as it loses significant moisture to the air and screen, so "used" ink going back into the bucket needs a bit of rehydration. I use distilled water. I would not trust the minerals and chlorine and fluoride and so forth in tap water to not be reactive with the ink.

You don't need parchment or anything protective under the prints, just on top.

Once cured, I don't think there should be any ruboff.

Are you print/flash/printing the ink or trying to lay it all down in one or two wet hits? I do 2 wet hits, flash, print, flash, print. But I'm using 200 mesh (USA) and aiming for a light weight but bright print on T-shirts. Your coarser substrate may well require a different approach. I would probably use a 156 mesh (USA) for canvas.

In the end testing and seeing what works is the way to go, but adding extra water is certainly adding to the cure time.
 

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Discussion Starter · #3 ·
That is a higher cure temp than I would aim for. A heat press directly imparts the heat through conduction, so the temp you set is pretty much the temp you get on the ink and fabric, unlike with radiant heat sources. 320F is the highest temp mentioned on the ink tub. I use 340F for one minute. 356F (180C) is potentially high enough to damage the ink.

I add a bit of water to mine as needed to maintain the original feel of the ink, as it loses significant moisture to the air and screen, so "used" ink going back into the bucket needs a bit of rehydration. I use distilled water. I would not trust the minerals and chlorine and fluoride and so forth in tap water to not be reactive with the ink.

You don't need parchment or anything protective under the prints, just on top.

Once cured, I don't think there should be any ruboff.

Are you print/flash/printing the ink or trying to lay it all down in one or two wet hits? I do 2 wet hits, flash, print, flash, print. But I'm using 200 mesh (USA) and aiming for a light weight but bright print on T-shirts. Your coarser substrate may well require a different approach. I would probably use a 156 mesh (USA) for canvas.

In the end testing and seeing what works is the way to go, but adding extra water is certainly adding to the cure time.
Hi,

Thank you so much for your detailed response, I really appreciate you taking the time to help me.

(1) Temp: I shall do some tests with your recommendation of a lower heat temp at 340F for the press. This was a passing suspicion of mine- that setting the Permaset with the press at 180’c (356F) was perhaps just setting the surface, or hardening the surface, rather than fully heat setting the ink all the way through? Am I along the right line of thinking, that your recommended lower temp would hopefully avoid the potential of it not setting all the way through?

A contextual note: My logic of me originally setting the press at 180’c (356F) was that after researching, many silk screen printers using water based ink said to set the press a bit higher than the Permaset Supercover recommended temp, to ensure the ink actually reached 160’c (320F). But I suppose this is what you do yourself at 340F but to a less dramatic degree than I have been doing. Hopefully your reccomendation will prove much better for me.

(2) Water dilution: Yes, this is the reason I too diluted my Permaset ink with 5% water, to maintain consistency of texture when compared with the original ink in the main tub, so it is reassuring to know this is something you also carry out and is standard practice for some. It has been hard finding anyone who has discussed their experiences with diluting their Permaset ink with a small percent of water and the effects of this on heat set times. Thank you for the tip on distilled water, I shall be using distilled water for dilution from now on.

(3) Rub off: Yes, it has been frustrating for me regarding rub off, knowing if it was normal or not. Obviously I would rather see zero when rubbing very firmly. But thank you for your experience with this. The rub off I have been experiencing when the fabric is dry has been minimal when I have rubbed quite hard, when rubbed lighter there visibly seems to be none, but the fact there can be some if rubbed hard enough does bother me. Also may I just confirm my thinking is correct in regards to rub and scratch tests being worse when a garment is wet?

Rub off continued: I actually remembered I was gifted a white cotton t-shirt that has a water based black line work print on it, I believe it has been professionally printed by a dedicated screen printing company for the artist who sells them. Anyway.. I did a rub test, using a dry q-tip on an area of the print, when the t-shirt was also dry and after checking the q-tip there was some black ink residue, comparable to my own prints. So it just made me wonder if this is just the nature of water based inks on cotton? A small degree of rub off is to be expected? But of course, you mentioned you do not believe that there should be any rub off. There seem to be so many hidden tricks and tips and things that are normal but at first do not seem it, it can be overwhelming to know what to dwell on and sort out and what is just a result of a particular process using certain materials! So apologies for all of my questions and I appreciate your help!

(4) Printing approach: Thank you for your recommendation of mesh count, I believe the UK 77T is the equivalent of the US 200 mesh. Sadly I do not believe there is a UK equivalent of the 156 US mesh in the UK, it is not something I have ever been able to source. However, I have done various test prints with a 55T UK (140 US) for my small finer bitmap work and found that much of the finer dot work detailing was lost with this mesh, and with the 77T (200 US) I was able to achieve.

Because of this, I have been using the 77T (200 US) for my small bitmapped fine dot work. As you mentioned, due to my use of coarser canvas rather than t-shirts, maintaining a light hand has not been a looming factor as I am printing onto a heavy weight canvas and the resulting garments will be structured, although I must mention my prints aren’t necessarily super ‘ridged’. My main aim has been to get the density of colour comparable to the original artwork, without over inking the print, maintaining crispness and detail, which I have achieved but in doing so, I have had to do a few passes with the squeegee (due to the using a slightly higher mesh to achieve the detail on the canvas). I do not flash dry between layers of printing as they are single image, black ink prints. I have been printing wet on wet hits. For my very small, bitmapped images on 77T (200 US) I have been doing 8 passes with my squeegee after the flood stroke, as this created the required opacity for the image. For line work and more simple artworks (which are still small but much less detailed and simpler on 43T (110 US)), I have been doing 4 passes (after the first flood stroke) for a nice opacity to the print. Of course, these are higher amounts of passes with my squeegee than I normally do for larger, less finely detailed prints or prints on paper, so likely result in an accumulative thicker layer of ink on the canvas, although it is not visibly thick, just the appearance of a good opacity to the print. Am I right in thinking, because of this, this would require a longer heat set time potentially, than lets say a standard cotton t-shirt print, that has fewer passes of the squeegee for a lighter hand print? May I also ask if this is the case, (that the print requires a lower temp and an accumulatively longer heat set), is it impossible to fully heat set it? Is the ink just too thick? And in a case where it is, is the print a lost cause and can never be heat set fully?

Apologies for the length of my response. As you can probably tell I have been accumulating many of these bugging questions for quite some time whilst I have been trawling page after page on google, and reading many forums and could no longer find the information I needed! Thank you in advance if you get the time to read through all of this and respond to my questions.

Many thanks,

Katherine.
 

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Oh, black ink. Sorry, I didn't even think about it being black ink. When you mentioned Supercover I assumed white, which is what most of my Supercover printing is. It might actually be easier if you used regular Permaset Aqua black rather than Supercover. It flows more readily through the mesh and would probably penetrate into the coarse fabric better than Supercover. Might be worth trying if you haven't already. I've never printed on canvas, so my assumptions about regular Aqua being better than Supercover may be misguided. Note, Supercover has a different body than regular Aqua, a bit more like Plastisol in that it builds up a layer or film, whereas regular Aqua pigments the fabric without building up a film.

Most of my blather in previous posts was based on printing white Supercover on black/dark garments, which requires flashing in order to build up an opaque film. But black ink can block out any underlying color without need of flashing or the extra thickness of Supercover. While I do have Supercover in various colors besides white, my black ink is regular Permasat Aqua. 200 mesh should work well for regular Aqua.

My mention of temp was about too high a temp potentially damaging the ink. I do not know how high is too high, but Permaset does mention that there is such a thing as too high. It is actually quicker to cure ink with a heat press than with a conveyor oven, as direct thermal conduction can more quickly and safely impart the correct temperature to the ink. Radiant heat sources are actually much hotter at the source than is desired for the ink, and depend upon the conveyor keeping the printed item under the heat long enough to reach the desired temperature, but short enough not to burst into flames.

As to the rub off test, I wouldn't do a wet rub off test until 24 hours after curing the ink. No customer is going to have their hands on the product and be washing it within 24 hours of it being printed. 24 hours is the time period I usually see mentioned before testing most any kind of print. My shop hoodie has some Supercover ink splatters that have never been cured, but after sitting on the hoodie however long, they will now not wash out (though they are softer than cured ink and no doubt would be damaged by picking and so forth).

The thickness of the canvass itself may require a bit more time curing as that is more mass for the press to heat up and the ink has probably penetrated farther into the fabric because the fabric is both thicker and coarser than a T-shirt. So maybe not directly comparable to the times I use for T-shirts. Short of someone with experience printing the same materials and curing with a heat press, you'll have to test variations and see what works (a good idea regardless). It may be unclear whether you have found perfection or simply good enough, but you want to know for sure that you've got some safety margin between that and failure.
 

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Oh, black ink. Sorry, I didn't even think about it being black ink. When you mentioned Supercover I assumed white, which is what most of my Supercover printing is. It might actually be easier if you used regular Permaset Aqua black rather than Supercover. It flows more readily through the mesh and would probably penetrate into the coarse fabric better than Supercover. Might be worth trying if you haven't already. I've never printed on canvas, so my assumptions about regular Aqua being better than Supercover may be misguided. Note, Supercover has a different body than regular Aqua, a bit more like Plastisol in that it builds up a layer or film, whereas regular Aqua pigments the fabric without building up a film.

Most of my blather in previous posts was based on printing white Supercover on black/dark garments, which requires flashing in order to build up an opaque film. But black ink can block out any underlying color without need of flashing or the extra thickness of Supercover. While I do have Supercover in various colors besides white, my black ink is regular Permasat Aqua. 200 mesh should work well for regular Aqua.

My mention of temp was about too high a temp potentially damaging the ink. I do not know how high is too high, but Permaset does mention that there is such a thing as too high. It is actually quicker to cure ink with a heat press than with a conveyor oven, as direct thermal conduction can more quickly and safely impart the correct temperature to the ink. Radiant heat sources are actually much hotter at the source than is desired for the ink, and depend upon the conveyor keeping the printed item under the heat long enough to reach the desired temperature, but short enough not to burst into flames.

As to the rub off test, I wouldn't do a wet rub off test until 24 hours after curing the ink. No customer is going to have their hands on the product and be washing it within 24 hours of it being printed. 24 hours is the time period I usually see mentioned before testing most any kind of print. My shop hoodie has some Supercover ink splatters that have never been cured, but after sitting on the hoodie however long, they will now not wash out (though they are softer than cured ink and no doubt would be damaged by picking and so forth).

The thickness of the canvass itself may require a bit more time curing as that is more mass for the press to heat up and the ink has probably penetrated farther into the fabric because the fabric is both thicker and coarser than a T-shirt. So maybe not directly comparable to the times I use for T-shirts. Short of someone with experience printing the same materials and curing with a heat press, you'll have to test variations and see what works (a good idea regardless). It may be unclear whether you have found perfection or simply good enough, but you want to know for sure that you've got some safety margin between that and failure.
Hi,

Yee I’m using black Supercover ink on a natural canvas (its an off-white colour). Not sure if I mentioned the ink colour in my previous post, so that may have been me leaving out needed details! Your point about using permanent Aqua, regular range is definitely a consideration, so thank you for mentioning this. I tend to usually stray away from using the regular range as I find it doesn’t quite get the richness of colour that the Supercover does. But as you say, perhaps the consistency may be better suited for the heavier canvas, so I can gradually build up thinner layers to achieve the opacity I need, whilst it not being stubborn to heat set. You’re right, it may not be the case but its worth a try and test!

Not blather at all, everything you have written has been super helpful, even if not directly relating to my scenario and materials, it gives me at least another reference point from someone who has been trying and testing configurations first hand.

Temp: Yes I have found it to be a tough one to gauge, there really seems to be a black art in finding a sweet spot that works. But as mentioned earlier, I have been heat setting some samples today with your recommendation of a lower temp, hopefully the results will be better, fingers crossed.

Rub test: Thanks for the recommendation for leaving it 24 hours before doing the test. You are so right about how customers won’t be handling, rubbing, washing or being rough with the garments before the 24 hour period. Its an excellent point as I have always been unsure what the appropriate period was to wait before doing any wash tests etc and with all of my tests previously I have only probably had a 1-2 hour wait after heat setting before testing, which now with hindsight sounds ridiculous! So yes, I shall be waiting 24 hours to test my new heat set samples.

Yes, you’re correct, the way forward will be just to continue with doing tests adjusting and recording results but now with more insight from your advice! And although as you say you personally have not printed with canvas, all this information you have taken the time to inform me on has been invaluable. Much appreciated.

Katherine
 
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