Will RED ink work as a substitute for BLACK on my film positives??
Hi!
I went by this office supply store yesterday looking for black ink for my printer (wich they offcourse did not have in stock..) As an option, this old geezer told me that a t-shirt printing friend of his used red ink instead of the normal opaque layer of black on his film positives. He claimed it would filter out the UV rays just as well as the black did, referring to the red lightbulbs used in darkrooms.
Will RED ink (magenta + a little yellow) really work as a substitute for black opaque ink on my film positives?
Well, to me it seems a bit far fetched, but I am still curious about this, so I'll try it out on a screen with 1/ 3 coats of diazo emulsion (which have been stored in the basement for three weeks now..)
By the way, I am completely new at this, so do not expect too much
Re: Will RED ink work as a substitute for BLACK on my film positives??
Hi,
Positives work by stopping uv light, not visible light. It is therefore possible that a red film (ruby masking film) could stop uv light.
Inkjet ink is formulated to last 75 years under glass (Epson) and they do this by adding uv block. Your red ink may stop enough light to make a positve. Curiously, the ink with the second highest density is yellow! (Epson again - they are the best printers for positives).
Basically, try it and see, you may have to lower your exposure if it's a bit marginal.
Several RIPs allow you to choose which channel to send the data to - see Wasatch at Wasatch RIP Software, SoftRIP for Inkjet Raster Image Processor Large Format Inkjet
Thanks
Dave
Quote:
Originally Posted by vrang
Hi!
I went by this office supply store yesterday looking for black ink for my printer (wich they offcourse did not have in stock..) As an option, this old geezer told me that a t-shirt printing friend of his used red ink instead of the normal opaque layer of black on his film positives. He claimed it would filter out the UV rays just as well as the black did, referring to the red lightbulbs used in darkrooms.
Will RED ink (magenta + a little yellow) really work as a substitute for black opaque ink on my film positives?
Well, to me it seems a bit far fetched, but I am still curious about this, so I'll try it out on a screen with 1/ 3 coats of diazo emulsion (which have been stored in the basement for three weeks now..)
By the way, I am completely new at this, so do not expect too much
Re: Will RED ink work as a substitute for BLACK on my film positives??
-HAHAHA!! IT ACTUALLY WORKED!!
The positive was a ruby red print with 100% Cyan / 100% Yellow on an ink-jet transparancy R-film done with a cheap HP printer.
The screen was a 110 mesh with one coating on the squeegee side, and three coatings on the print side.
Exposuretime was app. 8 min. (25" x 36" 8-bulb aluminum exposure unit from Ryonet).
Wash out by pressure washer at 1300 PSI.
The print came out really good! As crisp as they come using a 110, I believe. I also did a black film positive on the same screen (using the same crappy HP printer), which did not come out anywhere near as perfect as the red one did.
Maybe I was too focused on the red one? :P
Anyway, this only shows that using a red (magenta/yellow) print on an inkjet film actually works! It did block off enough UV light to make a decent print, at least for the set up I am using at the moment.
The lack of a proper printer has been a real pain in the arse! We are on a strictly limited budget, as we have yet to make any substantial income. We do however have (limited) acess to a half decent printer, but it is a ten minute drive from our workshop, and it too is currently out of black ink.. And there is off course the obvious drawback of coming home only to discover that you have to go back again because of a slight misprint..
So in reality; this means that we can get by using our crappy equipment, producing good results until we get enough $ for an upgrade!
Cheers!
Last edited by vrang; December 18th, 2008 at 05:41 AM.
Reason: type-0
Re: Will RED ink work as a substitute for BLACK on my film positives??
HOORAAAAHHHHHH!
However, you're probably putting too much ink down, try reducing the amount of ink going down, use just the magenta OR yellow, then add some more back in, you can do it on the same positive?
Dave
Re: Will RED ink work as a substitute for BLACK on my film positives??
Yeah, on the black version I probably put way too much ink down. It was all 100%(C+M+Y+K). Thanks for the advice!
Anyway. I'm glad I know of this solution, and I hope someone else will benefit from it too! I searched the forum, but could not dig up anything on the subject..
Re: Will RED ink work as a substitute for BLACK on my film positives??
Nice thread to revive.
This is a picture of the test I've done on an exposure together with a stouffer 21.
At the the upper right corner is the stouffer. It shows a solid 5. Most of my exposures were solid 6 but I lowered it to a solid step 5 as I was having some problems with ink opacity in the positive. This is one reason why I tried this test with one of my exposures.
The middle section shows the actual results. Disregard what appears to be incomplete wash out as that was a good exposure - meaning it may not be a perfect solid 7 but it was suitable for printing. I did not concentrate spraying on those areas. Anyway, the exposure was fine.
The bottom segment shows the film positive, or a jpeg version of it, that was used for the test. CMYK respresents 100% of each process colors respectively. M is for 100% Magenta and YK is for 100% magenta and 100% yellow or the color RED. The values at the very bottom, separated by a dash, are CMYK values. They represent selected colors on the UV spectrum from 400nm up to 700nm.
The 2 horizontal lines across the various colors are 1 and 2 point lines.
Sorry for the lousy angles of the shot but some portions on the left were not captured by the celphone. Nevertheless, what is important is that the middle segment shows a glimpse of the area covered by yellow ink and that it partially blocked UV (as evidenced by minor washout. Magenta does not appear to block UV. "K" or black ink blocks out UV. So does 100%M + 100%K, 100%Y + 100%K and 100%M +100%Y +100%K. All these color combination shows up as almost black on the film positive (bottom segment).
I am not sure if any conclusion can be drawn here, as I have yet to repeat this weeks-old test, but there is a possibility that only black, with or without combination of Magenta and Yellow are the only color combination that blocks out UV. Combination with other colors seems to be slightly better.
As to the color values representing selected colors of the UV spectrum, only the farthest right or darker colors show some signs of UV blocking by a partial but poor washout.
I've been wanting to do the exposure test again with emphasies on the UV blocking ability of various red, yellow and black color combinations but an extra hour added to mall hours (to an already long 11x7 schedule) prevented me from doing so.
This is in no way intended to refute others' claims as a colleague has exposed successfully using shades of yellow and magenta. Anyway, I decided to post this incomplete and inconclusive test in the hope that someone can contribute more information, offer opinions as to why on why my results are different, and forward suggestions.
Re: Will RED ink work as a substitute for BLACK on my film positives??
Nice one, it really does depend on the ink formulation. If it is full of uv block, it doesn't matter what colour the ink is! So everyone striving to get a really dense black from their printer - take heed.
Although your coloured ink isn't uv opaque enough, you can see that the yellow actually does a better job of stopping light than the magenta.
Re: Will RED ink work as a substitute for BLACK on my film positives??
I decided to do another test exposure but this time deliberately underexpose it. My earlier exposure was a solid 6 on the stouffer but look at the stouffer below. Sorry for the poor quality picture but those who are familiar with the stouffer will recognize the stouffer on the image and the solid 2 exposure - an extreme underexposure.
The same emulsion and number of coating was used but the earlier test was done on a 200 count white mesh and the second on a 180 count yellow mesh making the emulsion greenish.
At low UV levels and among the CMYK colors, it seems that cyan, followed by magenta are the least effective in blocking out UV. Black followed by yellow are the more effective.
The level of exposure or exposure time may also be one of the reason why other people get different results.
However, underexposure can yield a funny set of results. The 2 blue arrows indicate the start and end of all visible colors from 400-700nm. Under the right condition (rather wrong exposure condition), all these colors seems to block out UVs at varying degrees.
The film positive for the skull and crossbone is printed on 92 gsm inkjet friendly tracing paper but the colored squares are printed on tulco film transparencies which is more translucent than clear plastic but more transparent than tracing paper. It is generally considered good enough for professional screen printing exposures. Nevertheless, at a stouffer solid 2 exposure, even this film on top of a 92gsm tracing paper(3rd red arrow from top) or 2 layers of 92 gsm tracing paper (1st and 2nd red arrows from top) can block UV rays. The image was printed on 2 A4 tracing paper then taped together resulting in the overlap which normally wouldn't show in the exposure.
I think any exposures using non solid black ink should also indicate UV source, wattage, distance from lamp, and exposure time at the minimum to be meaningful.
This is a discussion about Will RED ink work as a substitute for BLACK on my film positives?? that was posted in the Screen Printing section of the forums.
Will RED ink work as a substitute for BLACK on my film positives?? 
