# Problems with making opaque positives from a laser printer



## face (Aug 4, 2007)

I'm somewhat new to screen printing, and I tried to expose a screen for the first time today. Unfortunately, I overexposed it, and the design did not wash out. However, I kind of expected this to happen, because my image positive was not as opaque as it should have been. I think that I could have probably exposed it for less time, and still have been successful, but I also think that a positive with greater opacity would be very beneficial. 

I created the positive with an HP Laserjet printer (2300 I think it is), which is the only laser printer that I have access to. I printed on these. When I hold up my positive, I can definitely see through the printed part, to a much greater extent than I would think is suitable. I printed with the highest resolution, and economy mode off. This is the only laser printer that I have access to. Would I have better success with an inkjet printer? The only inkjets that I have access to are decent, but not great. Any other suggestions.

Keep in mind, I'm doing this as a hobby for now, so although I may start selling later, for now I cannot put a lot of money into this.


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## Squirts (Feb 17, 2006)

face said:


> I'm somewhat new to screen printing, and I tried to expose a screen for the first time today. Unfortunately, I overexposed it, and the design did not wash out. However, I kind of expected this to happen, because my image positive was not as opaque as it should have been. I think that I could have probably exposed it for less time, and still have been successful, but I also think that a positive with greater opacity would be very beneficial.
> 
> I created the positive with an HP Laserjet printer (2300 I think it is), which is the only laser printer that I have access to. I printed on these. When I hold up my positive, I can definitely see through the printed part, to a much greater extent than I would think is suitable. I printed with the highest resolution, and economy mode off. This is the only laser printer that I have access to. Would I have better success with an inkjet printer? The only inkjets that I have access to are decent, but not great. Any other suggestions.
> 
> Keep in mind, I'm doing this as a hobby for now, so although I may start selling later, for now I cannot put a lot of money into this.


 Try spraying with toner enhancer, available from most screen printing suppliers.... will turn your images very opaque.... Chuck


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## Fluid (Jun 20, 2005)

Squirts said:


> Try spraying with toner enhancer, available from most screen printing suppliers.... will turn your images very opaque.... Chuck


clear lacquer in spray paint can form will work as well. Not as good as the industry but will work well. CaseysBlack I believe it is called or Caseys toner enhancer. something along those lines.


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## RichardGreaves (Nov 7, 2006)

Alas, you found out that transparency film for overhead projectors will not help increase the opacity of the toner. The film doesn't count, it's the toner.

The smooth surface of transparency film is OK for overhead projectors, but it can't hold enough toner to stop UV-A energy when you make screens.

This is why 'vellum finish' (a rough texture finish), transparent paper and textured polyester film is the choice of screen printers because it holds more toner. You could turn up the toner deposit like you can on a photocopy machine, but that also makes line and dots thicker. 

It also helps to increase the fuser temperature especially when you are trying to increase toner deposit - it takes more heat to thermally melt the toner in the fixed, very brief time, it takes to pass through the fuser. 

Spraying the inadequate toner with solvent can sometimes melt the toner enough to fill up the holes in the toner film, like melting shredded cheese on a pizza until it creates a film.

I know you spent lots of money on your HP but it's an office printer, not designed to print opaque toner to stop UV light and there is not an easy way to increase the toner deposit.


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## face (Aug 4, 2007)

RichardGreaves said:


> The smooth surface of transparency film is OK for overhead projectors, but it can't hold enough toner to stop UV-A energy when you make screens.
> 
> This is why 'vellum finish' (a rough texture finish), transparent paper and textured polyester film is the choice of screen printers because it holds more toner. You could turn up the toner deposit like you can on a photocopy machine, but that also makes line and dots thicker.


The transparency paper I have (linked in above post) is made for both inkjet and laser printers. It does this by having a rough side (for inkjet printers) and a smooth side (for laser printers). Will it work/is it a good idea to use the rough side of this, or do I need to get special vellum transparencies?


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## RichardGreaves (Nov 7, 2006)

face said:


> The transparency paper I have (linked in above post) is made for both inkjet and laser printers. It does this by having a rough side (for inkjet printers) and a smooth side (for laser printers). Will it work/is it a good idea to use the rough side of this, or do I need to get special vellum transparencies?


You linked to "Multipurpose Transparency Film CG6000". A key word here is 'film', which means it is not paper. 

If it works, it works. You are not using traditional screen making materials, so you are in uncharted territory. Products purchased from a screen printing supplier are guaranteed to work. I assume you are trying to save money, so you saw this as an alternative to established methods.

You can test your setup with a failure test. Print a 10" x 1" solid black line and do a step test of 1 minute per inch. If segments of the image don't wash out, UV-A energy leaked through and cross linked your stencil so it wouldn't dissolve with water and wash down the drain. Use a dime as a benchmark which will show how your stencil washes out without any exposure from your light source.


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## face (Aug 4, 2007)

Thank you all for your answers. I decided to try to print on the rough side of the film (I didn't know there was a distinction), but the increase in quality was marginal. I proceeded to do something that I was pretty sure would not work, but I was proven wrong. I carefully put the sheet of film back in the tray, lined it up, and printed on it again. It worked better than I could have hoped. The design was far darker after the second time through, and it lined up perfectly--no weirdness around the edges like I thought there would be. I proceeded to use it when I exposed my screen and it worked very well. There are some areas that the emulsion would not totally come out of, as I think it got a little bit too much exposure through the toner. I think though, that if I simply expose for a bit less time, my method of printing works very well.

For the record, I'm using a #1 (bba) lamp in a normal light reflector suspended a bit over a foot from the screen, and I exposed it for 8:45, I'll probably try a tad over 8 next time.


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## charles95405 (Feb 1, 2007)

I have a friend that prints two identical images..lines up one on top of the other..tapes in place...and it seems to work.


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## thaipressident (Jun 19, 2017)

When using a Laser printer to creates a mostly opaque coverage. However if you hold the artwork up to the light you will see that
light is getting through the black image to a small degree. The resist under the black laser printed image is actually getting light on it
and it is expose the resist . Even though you have tried all the DPIs (300, 600, 1200), but it keep getting a murky, splotchy and lean
image not solid black. 2 laser copies tape them together is darker but unclear edge. 
Laser toner density spray for use with laser printer or laser film to make solid black.Toner becomes darker and denser making
screen exposing more controllable. Halftones expose much easier and you will notice that you can burn much smaller dots without
problems. With density spray on your print settings “invert” the image the background prints in black and the images spreaded solid
black . Suitable for most laser printer.Not intended to work with inkjet (liquid) ink. Use in a well ventilated area.
[email protected]


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