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screen printing => Screen Making => Topic started by: StuJohnston on September 12, 2011, 03:21:31 PM
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I realize that I am far from expert in terms of screen making, but I do have a ton of experience at doing it wrong because of starting out as a hobbyist that was trying to go cheap. I am posting this here instead of the newb forum because I am offering some advice and I hope that more experienced people can offer some insight as the the why and how. I am also posting this topic to add some info on the more diy methods. I was also inspired by this thread, http://www.theshirtboard.com/index.php?topic=477.0 (http://www.theshirtboard.com/index.php?topic=477.0) I was also inspired by Gilligan's thread about vinyl stencils and the desire to find new methods of screen making.
I have used four different exposure methods, with cost in parenthesis:
- incandescent 150 watt bulb (free)
- mercury vapor 175 watt (free, but inexpensive to buy)
- metal halide 1000 watt grow lamp (roughly $200 from a hydroponics store including ballast and bulb)
- 5000 watt olec metal halide ($200 with contact frame, not terribly likely to find this unit at this price, but there are many small offset shops going out of business so it may not be so difficult. As I have mentioned elsewhere, after using this unit I would be willing to pay full price if another used unit was not available. It's that good)
And six types of emulsion, with estimated price in parenthesis, some are only by the gallon, usually quarts are 2/3 the gallon price.
- Speedball (I think it is something terrible like $30/Qt after purchasing the diazo)
- Ulano QX-1 (I think I paid about $17 when I got it from RJENNINGS and about $66 a gallon from Midwest)
- Kiwo one coat (free sample, didn't like it enough to buy any)
- Kiwo poly plus S (about $88/gallon)
- Kiwo poly plus SRX ($105/gallon)
- Kiwo poly plus HWR ($109/gallon)
I will give a brief description of these combinations in the format of exposure unit number first and emulsion second, so it would be 2:2 for for 175W MV and QX-1.
- 1:1 I didn't know any better, but I wouldn't recommend it to anyone since it would be either the same price or cheaper for a decent emulsion. Same with the light source, I had it laying around and the instructions for the speedball had times for it. I was slopping it on with a squeegee.
- 2:2 I bought this emulsion on the recommendation of Roger Jennings from one of his youtube videos, at least I think that was where I heard it. The instructions had an extensive list of exposure methods and ways of calculating things like distance to light source and dyed vs. undyed mesh. It just so happened that I had the MV lamp laying around, so I used that. It worked pretty well and exposed faster than a work lamp setup. I bought a sharp edge only coater with this emulsion.
- 2:3 I bought a gallon of QX-1 and the gal at the counter insisted that I take a sample quart of one coat, haha. To be honest, I didn't really see much difference. Perhaps it was due to my relatively weak exposure system. I still have some, so I will probably try it out with my current set up alongside the QX-1.Around this time, I started buying larger frames and needed to buy a larger coater. This one had a round edge in addition to the sharp edge, though I didn't start using the round side until later.
- 3:3 it was at this point that I got the calculator. The optimal time was relatively obvious because the low end would wash out nearly entirely and the high end pretty much didn't wash out at all. I started coating 2+2 with the round edge because I figured it would have a better chance of fully exposing than before. I was right.
- 3:4 This was the first time I got a stencil that cross linked really well with no sawtooth. I am not terribly proud of that fact, but there it is. The stencil was also incredibly hard, especially compared to the Ulano. Like the other poly plus emulsions, when I did the calculator test, it was somewhat difficult to determine the optimal time due to the fact that all of the film exposed fairly well. It was only after I started printing the test and looking at it with a loupe that I was able to discern the difference. I started trying thicker coatings and was able to get a 200 micron film of ink using TW11000 black on vinyl. Of course, I don't intend to make that a habit, but it adhered just fine.
- 3:5 Similar to the poly plus S, but a little longer exposure.
- 4:6 Oddly, I swear that the SRX smells like dead fish so I asked the salesguy at midwest about it. He asked Kiwo and they said that the batch that my gallon came from didn't have any problems and it shouldn't be that way, or at least that it is subjective. He did order a sample of HWR since I was looking for a do-it-all emulsion that performed like the other poly plus emulsions that I had tried. Thankfully, it has a sweet smell and it seems like the best emulsion yet, it has great mechanical strength and it holds good detail even on low mesh counts.
- Just for grins, 3:1. Predictably, it was really bad. I used the Ulano sample calculator and there was a nice diagonal line of bad detail, which I take to mean that there isn't a sweet spot
Some things that I have learned it this process:
- A fast exposing emulsion like QX-1 at least seems to work better with weak light sources.
- Slower exposing emulsions + strong light source is awesome and worth the higher price.
- In my experience, weak light sources seem to have a finer line between under exposure and over exposure. Which led me to the conclusion that I had to slightly under expose and then post harden in the sun
- Integrators make exposure a pretty brainless exercise once you get the times dialed in.
- Some people seem fixated on fluoro units even in the presence of evidence that single point is superior.
I know that some may scoff at my preference of a relatively expensive emulsion, but I would rather get it right the first time than go through several more emulsions to find one that does everything that the HWR does and as well as it does. Also, the emulsion info is probably more suited to solvent flatstock than plastisol or discharge textile, but the light source info might help. Also, the HWR should be able to run anything you throw at it, if you are willing to spend the money.
I should relate a couple of my more spectacular mess ups as they relate to screen making. When I got the sample of one coat, I somehow mistook it for qx-1 and tried to print with solvent, I think that I had screens coated with both at the time in the dryer. It took about three pulls to disintegrate the stencil to a blur. I actually tried two quarts of one coat because I think I did a poor job of mixing the diazo such that my exposure times kept getting shorter as I got further into it, lol.
While I can understand how some people, who have no printing aspirations beyond shirts for their band or a few posters might be ok with DIY methods and cheap supplies, but with making money in mind I often think of this Henry Ford quote that I read in a book about making a machine shop profitable from early 20th century, "If you don't buy the tools you need, you will eventually pay for it, but not have your tool."
To wrap this up and to give a cost comparison of exposure methods. Of course, the unsuitability of multiple light source units is well documented, I think that most people who consider this method don't actually figure out the cost to make it the 'right' way. I took a look at platt electric for the supplies necessary to build a fluoro unit. Real blacklight bulbs, ballasts and lamp holders for a unit the same size as mine would run at least $600 (roughly). Not including the plywood, glass and incidental supplies. Or, you know, you could get a grow light for $200, expose in a fraction of the time (see, http://www.ulano.com/TechData/QX-1.tds.pdf (http://www.ulano.com/TechData/QX-1.tds.pdf)) and actually get decent detail, but what do I know? I left out the cost of a vac frame, but it would be the same price in either case.
As I have mentioned, I am still pretty new at this and this is just my anecdotal report. I welcome any differing opinions. Most of this info comes from tech sheets, articles, forums, youtube and experience. I feel a little exposed with so many words. Also, regarding youtube, I read on here that youtube is always an example of how not to screenprint, I think that Roger Jennings does a fair job of explaining some of the basics of screenprinting. He is a little coarse though.
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* Some people seem fixated on fluoro units even in the presence of evidence that single point is superior.
Not sure where you get that from I never heard anyone think Flouro is better.
I personally only have a Flouro and I can shoot screens with the best of the up to a point of course. I find a fast exposing good latitude emulsion is perfect and does not in any way require under exposing, under exposing causes many issues especially with scumming.
If I did have a single point I would use higher quality slower exposing emulsions as well but I will say a Flouro unit is only as good as the person using it and in my case i shoot perfect screens day in and day out.
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The fluoro comment comes mostly from seeing so many diy exposure units made with multi point light and specifically from a few discussions with friends off the internet. I got a few crazy looks when I said that I planned to build the MH unit.
I wouldn't classify fluoro boxes as weak in the same way that my mercury vapor lamp and incandescent were. Or weak at all for that matter. I have heard of people getting good quality stencils from fluoro boxes as well. Just out of curiosity, what led to getting the fluoro box?
There are some powerful fluoro boxes come to think of it, there is one at screwball press that supposedly will get perfect stencils in ten seconds with QX-1. The guy who runs it had a violux (or some equally powerful single point source, it could have been carbon arc. in that case, nevermind) unit that he gave away for the cost of shipping even.
For full disclosure, I got into the idea of a single point light source because of Roger Jennings and his, I am not sure if this is the right word but, fanaticism.
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Roger believes in the single point enough to encourage DIY halogen. He seems to shy away from MH as I seem to remember him saying that they were hard to obtain (and of course would generally require a shutter of some sort, further complicating the project).
There are many fluorescent units that perform well enough to produce award winning shirts and great selling retail pre-prints. The shop I used to work at can attest to this.
A fluorescent with a vacuum may easily outperform a single point MH without.
One reason that multi-tube units are popular with DIY, is that the cabinet part is much easier to build and also they are more compact to fit on an existing table rather than requiring space as a stand-alone.
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Roger believes in the single point enough to encourage DIY halogen. He seems to shy away from MH as I seem to remember him saying that they were hard to obtain (and of course would generally require a shutter of some sort, further complicating the project).
There are many fluorescent units that perform well enough to produce award winning shirts and great selling retail pre-prints. The shop I used to work at can attest to this.
A fluorescent with a vacuum may easily outperform a single point MH without.
One reason that multi-tube units are popular with DIY, is that the cabinet part is much easier to build and also they are more compact to fit on an existing table rather than requiring space as a stand-alone.
Most often the multi-tube units come down to cost...
If one only needs to shoot a screen or two in a few hours then it becomes difficult to justify the longer ROI in a MH system.
Speed and cost...
There are some powerful fluoro boxes come to think of it, there is one at screwball press that supposedly will get perfect stencils in ten seconds with QX-1.
I don’t think this exists, I would have to see it to believe it - even the high Wattage UVB FL tubes cannot come close to that, at least not with a correct and FULL exposure.
Of course that is the problem, ask any emulsion rep how many people underexpose screens and the answer is “all of them” or “99.999999%”...
I have seen nothing out in the wild to contradict that point of view.
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I'm using Flo bulbs in a vacuum unit.
High output unfiltered blacklight bulbs with a 365n range. I paid 10 bucks a bulb, could have spent 24 a bulb for the 385n rating but i need 12 bulbs and for that kinda joe and the amount of screens i burn, these work fine. Shoot 330's 55line screen with Ulano 925WR @3 minutes and it's perfectly exposed.
I can shoot the same screen in the sun for 30 seconds.
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Roger believes in the single point enough to encourage DIY halogen. He seems to shy away from MH as I seem to remember him saying that they were hard to obtain (and of course would generally require a shutter of some sort, further complicating the project).
There are many fluorescent units that perform well enough to produce award winning shirts and great selling retail pre-prints. The shop I used to work at can attest to this.
A fluorescent with a vacuum may easily outperform a single point MH without.
One reason that multi-tube units are popular with DIY, is that the cabinet part is much easier to build and also they are more compact to fit on an existing table rather than requiring space as a stand-alone.
For some reason I thought that Roger recommended MH. I would agree that MH is definitely more expensive, but shouldn't be hard to obtain. At least not around here, there are at least five hydroponic stores within ~30 minutes of my house in the woods. People around here sure do like tomatoes in the winter, lol. I built my box with a shutter, very crude, but it worked. It was just a sheet of plywood in a slot in the box over the lamp.
I have not seen that screwball unit either, so I cannot actually verify. I agree that it seems unlikely as ulano only claims 40 seconds on a 1:1 305T White mesh. Where would you get white 305T? Why would you get white 305T?
I hadn't thought of the counter ability of fluoro units, but if you get into the larger units, that capability goes away anyhow. I suppose this is more an issue for flatstock. I can't say for certain but it seems that textile printers tend to use smaller screens on average. My 23x31 screens are starting to feel cramped.
I figured that the exposure unit discussion was a little more grey than I had thought, like the shur loc discussion. The original idea behind this thread was to share emulsion experiences, but I got distracted. on the original idea, it was because the detail often doesn't go far beyond, "I like brand y emulson" then "I don't like brand y, I find brand x to work the best." What is often missing is method of exposure and specific reasoning behind liking or not liking certain emulsions.
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I have been using Aquasol HV for a few months now and absolutely love it! It is working great with a Flouro unit even with a heavy EOM which you can get serious with this emulsion. The latitude seems great as well.
I tend to be stupid and try different emulsions over time usually with the same results and that is most are not meant to be used with a Flouro unit. The trick to using a flouro unit is finding the correct emulsion and finding the correct exposure times. Once you have been diligent in finding the right combination you can do almost anything a powerful single point can do almost. The big draw back is obviously longer exposure times. Doug said something about most Flouro guys being under exposed well in my case i tend towards a little over, I would rather work a bit longer in developing than have to deal with scumming and locked in emulsion. You can take any of my screens directly from developing still wet and with a white rag wipe the inside and it will still be white. Scumming is never an issue for us. We run maybe two dozen 4cp jobs a year and I always burn with our Flouro unit with great results.
I do want a single point soon not because of quality but for speed, we are burning more and more screens than ever and the time in the unit is becoming a bit of a bottle neck.
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For some reason I thought that Roger recommended MH. I would agree that MH is definitely more expensive, but shouldn't be hard to obtain. At least not around here, there are at least five hydroponic stores within ~30 minutes of my house in the woods. People around here sure do like tomatoes in the winter, lol. I built my box with a shutter, very crude, but it worked. It was just a sheet of plywood in a slot in the box over the lamp.
I remember a video he made called Screen Printing's best Exposure Unit, and it used a Halogen light.
Here it is Listen to his statement at about 3:53.
Screen Printing's Best Exposure Unit (http://www.youtube.com/watch?v=x9NrndxeCJ4#)
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That's the one I was thinking about actually, it had been some time since I had watched that video. All I remembered was 1000 watts and Nuarc eventually, when you are making enough money and want to get really serious about it. I recall that he said that if you are paying more than $70 for the light, you are getting ripped off. That makes more sense now that I realized that he isn't talking about MH.
I actually must disagree with his recommendation of halogen lights. At least the commonly available worklights. Unless you are getting them for free, they aren't worth it imo. I might even suggest a fluoro unit before a worklight setup if economy is a concern.
He mentions the sun in that video. I have a little experience with that, yet it seems to be a little slower than the Olec unit I am using. I know that Andy Macdougall uses the sun almost exclusively. He has a vac frame that will point toward a large window. The trick is, he has a radiometer. For some reason, I had thought that the integrator that came with my lamp would measure UV like a radiometer. Apparently is doesn't. Do any of you guys use a radiometer, either for testing exposure units or exposing in the sun? For that matter, I can't seem to figure out what these 'light units' are that I have seen here regarding integrators.
Inkman996, omg, using a fast exposing emulsion like QX-1, the burn times are arount 2.5-20 seconds depending on coating method according to the tech sheet using my current setup! I don't know what your fluoro set up is like now, but it may be worth it to look into making your own grow light unit. Or just look at craiglist obsessively like I did. According to the Qx-1 tech sheet, with a 1000 watt grow light, it should take about a third of the time of the fluoro unit. When I was exposing with the grow light, the tech sheet was pretty accurate. I should burn a screen or two of the qx-1 for the sake of novelty, and using up the stuff, lol.
I just noticed that the Murikami ( brand favored by water based flat stock people BTW) says that a 300T screen at 40" will take 35-40 seconds with a 5kW lamp. For the sake of comparison, where are your exposures Inkman? Thanks for your contribution btw. Any other emulsion that worked well, or not at all with a fluoro unit?
I haven't looked at a ton of tech sheets, but the default exposure unit seems to be a 5kW unit. Only the Qx-1 has given times for lesser powered units. I suppose it's easier to just try it out on one unit, but come on, it would be nice to see at least a rough calculation of modifiers for other types of exposure units. I would hazard a guess that most printer do not have a 5kW unit.
I had a thought, the film that I am using now seems to get a pretty deep ink deposit. At least, so it seems. If you got a dark enough and deep enough film, could the issues with fluoro be alleviated?
About the glisten method, I re read the article and I am not sure I have it right. Does this mean that I should coat the print side until the squeegee side glistens and then one or two coats from the squeegee side?
I must admit, the other motivation for this thread and the other is to gather info for an info graphic and possible pamphlets that I am making with a fellow graphic designer for beginning/hobby printers so that they can get an idea of what to expect when using proper emulsion (not speedball.)
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About the glisten method, I re read the article and I am not sure I have it right. Does this mean that I should coat the print side until the squeegee side glistens and then one or two coats from the squeegee side?
pretty much, that's what makes it fairly easy. We have the same visual clue no matter the mesh count.
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GREAT writeup stu! Thank you for taking the time to do it!!!
pierre
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This discussion has me wondering how I would do with a flouro exposure unit. I feel like I would struggle since all I've ever used was a 10K watt metal halide. I know lot's of you have perfected your screen making with flouro exposure units and probably make as good a stencil as we do with our unit, and I applaud that. One thing I'm grateful for is having had the stencil making process made very easy for us.
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This discussion has me wondering how I would do with a flouro exposure unit. I feel like I would struggle since all I've ever used was a 10K watt metal halide. I know lot's of you have perfected your screen making with flouro exposure units and probably make as good a stencil as we do with our unit, and I applaud that. One thing I'm grateful for is having had the stencil making process made very easy for us.
You would hate going “backwards” in this area.
You may be looking at this a bit wrong... “as good as” is not the correct path to go down.
Obviously you can completely and fully expose a screen from face to squeegee side with a multi-tube-bulb unit, is that the definition of “as good as” the answer is more complicated as is usual in this industry.
How do they stack up side by side?
MFBU (multi fluorescent bulb unit)
SBMH (single bulb Metal Halide)
MFBU - longer exposure time
SBMH - shorter exposure time
MFBU - loss of 17% of high end details - 17% less than possible with SBMH (not 17% off the top from the image), somewhat compensates for dot gain on low end (again about 17%)
SBMH - holds more of the hight end details, will continue to have all of the gain expected in low end.
MFBU - typically smaller
SBMH - larger but often self contained
MFBU - less expensive
SBMH - more expensive, typically lots more features (like a memory of typical times)
MFBU - bulbs are more consistent over a longer time, longer active life
SBMH - bulbs drop in UV output much faster, craze to the point of choking off large amounts of UV at about three months of typical use