Homebrew PCBs

Hello, new member here.

I joined because I think this should be the best place to solve a
problem I'm having with a dry film I'm testing (never used this method
before).

The stuff I'm testing is this:
http://www.es.co.th/Detail_eng.asp?Prod=WARA%2DDRYFILM

I get it locally (I live in Bangkok), and unfortunately the
instructions are in Thai... my girlfriend helped me out with it but I
still think there may be something wrong with them... 

But first let me lay out the scene.

Of course first I prepare the board, just before applying the film
sand it over with 600 grit sandpaper, buff it up with Brasso polisher,
rinse and clean with water and then final wiping with alcohol. I get a
very pleasing mirror finish! =)
No fingerprints, lint or dust on the PCB before applying the film.

I cut a piece of film slightly larger than the PCB area, remove the
backing layer and stick it to the PCB starting by and edge and using a
cloth to easily slide my fingers around the sticking edge as I lay it
down. No bubbles or anything, it adheres very well on its own.

I place a cloth over the PCB and film and use an iron on Silk setting
to fuse the film to the board, if I use a higher temperature the film
seems to liquefy under the backing film and make nasty spots... not
good. With some practice I've managed to do it right most of the time.

After ironing I place the negative mask over the board and expose it
with an incandescent light bulb for an hour until the exposed film
turns a darker blue. So far so good, the traces look perfect and the
backing film peels off easily.

Everything goes wrong when I try to wash away the unexposed film. Per
the instructions I used all the developer powder provided (about 50
grams of calcium carbonate) on 200cc of water. The instructions simply
say to use a sponge to wipe out the unexposed film, at first seems to
work but then the finer traces (0.3mm) start to break and by the time
the unexposed film is gone all looks mangy and frankly quite FUBARed.

I suspect the developing solutions is not correct, but having no
experience with this method I couldn't tell.

The bulk of my ignorance is the developing process, what is the
standard way of developing and cleaning the excess dry film?
-Should I do it right after exposing it, or should I leave the board
in a dark place for some time?
-Should I go at it with the sponge right away or first leave the PCB
submerged on the developing solution for some time?

I would appreciate very much some insight from the people in this group.

Cheers,

Ale

I use Adam's wet method - rinse the film and use a squeegie and hot
air gun to laminate it.  But, if you're just short of melting the
film, I think you've got that covered.

The film I use requires a 15 minute "rest" period after exposure - in
the dark and before the second cover film is removed - to fully cure.
Try to find instructions you can read.

I use NO mechanical wiping to develop.  Just drop it in the solution
and wait.

You may also have underdeveloped the film.  I got a step gauge to
calibrate with, but you may be able to calibrate without by
experimenting with a striped mask and finding the least exposure where
the exposed mask stays, and the most exposure before the covered mask
hardens.  Then choose something between the two.

Incandescent lamps may not be the best source of UV.  UV LEDs are
cheap enough to buy in bulk, or try sunlight, which is more variable
(weather) but high in UV.

If your film has two cover films, make sure you're removing the right
one first.

"pixelcanvas"  wrote:
>

> The stuff I'm testing is this:
> http://www.es.co.th/Detail_eng.asp?Prod=WARA%2DDRYFILM
> 
> I get it locally (I live in Bangkok), and unfortunately the
> instructions are in Thai... my girlfriend helped me out with it but I
> still think there may be something wrong with them... 
> 

As this appears to be Wara product try the manufacturers web site to
confirm your translation was correct.

http://www.warapcb.com/dryfilm.php

All the best
Warren

On Fri, 10 Oct 2008 13:33:03 -0000, you wrote:

There are two things that might be wrong that come to my mind.

1) you may have too strong a developer.  Not sure, never used it.

2) if the film exposes from the top down, insufficient exposure can
cause a bottom layer of film to be unexposed and soluble. The wider
traces stay on because the developer can't dissolve the unexposed
resist fast enough.

Solution for #2 is to expose longer, or use UV lights, or whatever the
manufacturer recommends (never used the product, but experience is
drawn from other photosensitive processes.).

I'd look at doing a test exposure from about 1/4 the amount of time
you think needs to be done to 2 or 4x the amount of time.  Make it a
small board, and see where you get the best results for time and light
intensity.

Harvey

>Hello, new member here.
>
>I joined because I think this should be the best place to solve a
>problem I'm having with a dry film I'm testing (never used this method
>before).
>
>The stuff I'm testing is this:
>http://www.es.co.th/Detail_eng.asp?Prod=WARA%2DDRYFILM
>
>I get it locally (I live in Bangkok), and unfortunately the
>instructions are in Thai... my girlfriend helped me out with it but I
>still think there may be something wrong with them... 
>
>But first let me lay out the scene.
>
>Of course first I prepare the board, just before applying the film
>sand it over with 600 grit sandpaper, buff it up with Brasso polisher,
>rinse and clean with water and then final wiping with alcohol. I get a
>very pleasing mirror finish! =)
>No fingerprints, lint or dust on the PCB before applying the film.
>
>I cut a piece of film slightly larger than the PCB area, remove the
>backing layer and stick it to the PCB starting by and edge and using a
>cloth to easily slide my fingers around the sticking edge as I lay it
>down. No bubbles or anything, it adheres very well on its own.
>
>I place a cloth over the PCB and film and use an iron on Silk setting
>to fuse the film to the board, if I use a higher temperature the film
>seems to liquefy under the backing film and make nasty spots... not
>good. With some practice I've managed to do it right most of the time.
>
>After ironing I place the negative mask over the board and expose it
>with an incandescent light bulb for an hour until the exposed film
>turns a darker blue. So far so good, the traces look perfect and the
>backing film peels off easily.
>
>Everything goes wrong when I try to wash away the unexposed film. Per
>the instructions I used all the developer powder provided (about 50
>grams of calcium carbonate) on 200cc of water. The instructions simply
>say to use a sponge to wipe out the unexposed film, at first seems to
>work but then the finer traces (0.3mm) start to break and by the time
>the unexposed film is gone all looks mangy and frankly quite FUBARed.
>
>I suspect the developing solutions is not correct, but having no
>experience with this method I couldn't tell.
>
>The bulk of my ignorance is the developing process, what is the
>standard way of developing and cleaning the excess dry film?
>-Should I do it right after exposing it, or should I leave the board
>in a dark place for some time?
>-Should I go at it with the sponge right away or first leave the PCB
>submerged on the developing solution for some time?
>
>I would appreciate very much some insight from the people in this group.
>
>Cheers,
>
>Ale

--- In Homebrew_PCBs@yahoogroups.com, "warrenbrayshaw"
<warrenbrayshaw@...> wrote:
>
> "pixelcanvas"  wrote:
> >
> 
> > The stuff I'm testing is this:
> > http://www.es.co.th/Detail_eng.asp?Prod=WARA%2DDRYFILM
> > 
> > I get it locally (I live in Bangkok), and unfortunately the
> > instructions are in Thai... my girlfriend helped me out with it but I
> > still think there may be something wrong with them... 
> > 
> 
> As this appears to be Wara product try the manufacturers web site to
> confirm your translation was correct.
> 
> http://www.warapcb.com/dryfilm.php
> 
> All the best

Yes, the translation is correct, but I have serious dubts about it's
usefulness. For example it does say to use a 100W light bulb for 15
minutes to expose the film, and I know for a fact that is way too
little time. So I think I should take those instructions with a pretty
large grain of salt...

Harvey, I think what you are saying about the bottom of the film not
being exposed may be correct.
I'm going to try to get an UV light, and expose a test board at
different times, I'll place a piece of cardboard over it and move it
to the side every 15 minutes or so to expose more of the board. Then
I'll see what exposure time works best.

Thanks  lot for the suggestions so far.
> Warren
>

On Sat, 11 Oct 2008 01:50:08 -0000, you wrote:

>--- In Homebrew_PCBs@yahoogroups.com, "warrenbrayshaw"
><warrenbrayshaw@...> wrote:
>>
>> "pixelcanvas"  wrote:
>> >
>> 
>> > The stuff I'm testing is this:
>> > http://www.es.co.th/Detail_eng.asp?Prod=WARA%2DDRYFILM
>> > 
>> > I get it locally (I live in Bangkok), and unfortunately the
>> > instructions are in Thai... my girlfriend helped me out with it but I
>> > still think there may be something wrong with them... 
>> > 
>> 
>> As this appears to be Wara product try the manufacturers web site to
>> confirm your translation was correct.
>> 
>> http://www.warapcb.com/dryfilm.php
>> 
>> All the best
>
>Yes, the translation is correct, but I have serious dubts about it's
>usefulness. For example it does say to use a 100W light bulb for 15
>minutes to expose the film, and I know for a fact that is way too
>little time. So I think I should take those instructions with a pretty
>large grain of salt...
>
>Harvey, I think what you are saying about the bottom of the film not
>being exposed may be correct.
>I'm going to try to get an UV light, and expose a test board at
>different times, I'll place a piece of cardboard over it and move it
>to the side every 15 minutes or so to expose more of the board. Then
>I'll see what exposure time works best.

For commercially available boards (GC electronics), board about 8
inches from the lamps, lamps 18 inch 15 watt black lamp fluorescent
(not what's recommended, I think), I get about 3 minutes exposure.
Multiple lamps seems to help.  I've got a homemade vacuum frame
(particle board and a shop vac with a lot of holes in the particle
board) and I use thin upholstery vinyl (transparent, of course) over
the board.

a 100 watt lamp is mostly red and yellow.  If it's supposed to be
exposed under UV or blue/white light, then you might see a recommended
wavelength in the resist technical characteristics.

The normal photoresist polymerizes (or de polymerizes) from the top
down.

Harvey

>
>Thanks  lot for the suggestions so far.
>> Warren
>>
>

Hi ,The picture of the lamp in the instructions looks like a sunlamp (UV) 
type of lamp by the shape. There is no description as to what the film is 
sensitive to, every resist I have seen used over the last 30 years has been 
UV sensitive.
Don VK3YV

----- Original Message ----- 
From: "pixelcanvas" <pixelcanvas@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, October 11, 2008 12:50 PM
Subject: [Homebrew_PCBs] Re: Dry film woes, maybe the developer is at fault?


> --- In Homebrew_PCBs@yahoogroups.com, "warrenbrayshaw"
> <warrenbrayshaw@...> wrote:
>>
>> "pixelcanvas"  wrote:
>> >
>>
>> > The stuff I'm testing is this:
>> > http://www.es.co.th/Detail_eng.asp?Prod=WARA%2DDRYFILM
>> >
>> > I get it locally (I live in Bangkok), and unfortunately the
>> > instructions are in Thai... my girlfriend helped me out with it but I
>> > still think there may be something wrong with them...
>> >
>>
>> As this appears to be Wara product try the manufacturers web site to
>> confirm your translation was correct.
>>
>> http://www.warapcb.com/dryfilm.php
>>
>> All the best
>
> Yes, the translation is correct, but I have serious dubts about it's
> usefulness. For example it does say to use a 100W light bulb for 15
> minutes to expose the film, and I know for a fact that is way too
> little time. So I think I should take those instructions with a pretty
> large grain of salt...
>
> Harvey, I think what you are saying about the bottom of the film not
> being exposed may be correct.
> I'm going to try to get an UV light, and expose a test board at
> different times, I'll place a piece of cardboard over it and move it
> to the side every 15 minutes or so to expose more of the board. Then
> I'll see what exposure time works best.
>
> Thanks  lot for the suggestions so far.
>> Warren
>>
>
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and 
> Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>


--------------------------------------------------------------------------------



No virus found in this incoming message.
Checked by AVG - http://www.avg.com
Version: 8.0.173 / Virus Database: 270.8.0/1719 - Release Date: 10/10/2008 
4:08 PM

On Sat, 11 Oct 2008 17:28:36 +1100, you wrote:

The original Kodak KPR liquid resist was short wave UV sensitive.  You
used bare mercury arc fluorescent bulbs with a major amount of
shielding to you couldn't see them.  That's the same thing that turns
out to be a germicidal lamp.  Sufficient exposure of your eyes to this
stuff causes permanent blindness.

The positive acting resists that are currently available seem to be
exposed with either blue/white (8000 degree K) light a la MG chemicals
instructions or longwave UV which seems to work well on GC chemicals
boards.

Exposure through a printed transparency (black laser) is touchy, since
the laser print is not completely opaque.  Can be done, though, if
you're being careful.

Have since switched to DS work with toner transfer.

Harvey

>Hi ,The picture of the lamp in the instructions looks like a sunlamp (UV) 
>type of lamp by the shape. There is no description as to what the film is 
>sensitive to, every resist I have seen used over the last 30 years has been 
>UV sensitive.
>Don VK3YV
>----- Original Message ----- 
>From: "pixelcanvas" <pixelcanvas@...>
>To: <Homebrew_PCBs@yahoogroups.com>
>Sent: Saturday, October 11, 2008 12:50 PM
>Subject: [Homebrew_PCBs] Re: Dry film woes, maybe the developer is at fault?
>
>
>> --- In Homebrew_PCBs@yahoogroups.com, "warrenbrayshaw"
>> <warrenbrayshaw@...> wrote:
>>>
>>> "pixelcanvas"  wrote:
>>> >
>>>
>>> > The stuff I'm testing is this:
>>> > http://www.es.co.th/Detail_eng.asp?Prod=WARA%2DDRYFILM
>>> >
>>> > I get it locally (I live in Bangkok), and unfortunately the
>>> > instructions are in Thai... my girlfriend helped me out with it but I
>>> > still think there may be something wrong with them...
>>> >
>>>
>>> As this appears to be Wara product try the manufacturers web site to
>>> confirm your translation was correct.
>>>
>>> http://www.warapcb.com/dryfilm.php
>>>
>>> All the best
>>
>> Yes, the translation is correct, but I have serious dubts about it's
>> usefulness. For example it does say to use a 100W light bulb for 15
>> minutes to expose the film, and I know for a fact that is way too
>> little time. So I think I should take those instructions with a pretty
>> large grain of salt...
>>
>> Harvey, I think what you are saying about the bottom of the film not
>> being exposed may be correct.
>> I'm going to try to get an UV light, and expose a test board at
>> different times, I'll place a piece of cardboard over it and move it
>> to the side every 15 minutes or so to expose more of the board. Then
>> I'll see what exposure time works best.
>>
>> Thanks  lot for the suggestions so far.
>>> Warren
>>>
>>
>>
>>
>> ------------------------------------
>>
>> Be sure to visit the group home and check for new Links, Files, and 
>> Photos:
>> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>>
>>
>>
>
>
>--------------------------------------------------------------------------------
>
>
>
>No virus found in this incoming message.
>Checked by AVG - http://www.avg.com
>Version: 8.0.173 / Virus Database: 270.8.0/1719 - Release Date: 10/10/2008 
>4:08 PM

Well, so...

I bought a handful of 5mm UV LEDs (40) soldered on a bradboard in
groups of 2 LEDs in series because I only had a 7808 voltage regulator
at hand, so every lED on each pair gets 4 volts at 30mA.
I made a 17cm high enclosure with cardboard, lined with aluminum foil
on the inside, I get a fairly even surface of light at the bottom,
although a bit more concentrated at the center.

I wasn't sure it would work after reading how some people are using
powerful UV lights but I gave it a try so I exposed a test PCB for 15
minutes. The film turned a deep purple colour, before it was only
getting to dark blue so I took it as a good omen!

I hadn't actually ironed the film to the board but so again I wasn't
expecting the developing to go well, but I mixed a couple spoons of
Sodium Carbonate (you're right, not calcium carbonate... I know that's
chalk *slaps forehead*) on about half a liter of water, droped the PCB
and just let it seat there while I stirred the water a little. Lo and
behold the unexposed film started to disolve and the cooked lines
remained in place. Perfect!

However I didn't etch the PCB because the traces peeled rather easily.
Obviously a little ironing should fix that.

Now I'm going to try again with the board I wanted to make and see how
does that goes.

Thanks a lot for all the help, I'll update how the PCBs come out.

-Ale

So this is how the first boards turned out:
Picture link
<http://s155.photobucket.com/albums/s282/sawasdee_che/Electronics/?actio\
n=view�t=IMG_3462.jpg>

The boards are 2x1.5 cm, to give an idea of their size.
The film is surprisingly resilien after it sets, I scrubed it pretty
hard with an abrasive sponge and it took me a long time to scrape it off
one corner. I have to buy some thinner to dissolve it.



[Non-text portions of this message have been removed]

"pixelcanvas" <pixelcanvas@...> writes:
> The film is surprisingly resilien after it sets, I scrubed it pretty
> hard with an abrasive sponge and it took me a long time to scrape it
> off one corner. I have to buy some thinner to dissolve it.

Try sodium hydroxide (lye, drain cleaner) - about the same
concentration as the developer.  For my film, I drop it in that long
enough to soften the film.  When it looks like it's starting to come
off on its own, I take it out and scrape it off with a plastic card.
If you leave it in long enough, it comes off completely and stays in
the tank.

I'm starting to get good results out of this stuff. Here's a TQFP
adapter board I made for an ATMega48.

http://s155.photobucket.com/albums/s282/sawasdee_che/Electronics/?action=view¤t=TQFP32_A.jpg
http://s155.photobucket.com/albums/s282/sawasdee_che/Electronics/?action=view¤t=TQFP32_B.jpg
http://s155.photobucket.com/albums/s282/sawasdee_che/Electronics/?action=view¤t=TQFP32_C.jpg
http://s155.photobucket.com/albums/s282/sawasdee_che/Electronics/?action=view¤t=TQFP32_D.jpg

Soldering that chip was surprisingly easy, once I got it aligned and
two pins soldered in place it the rest was a breeze.
I used acrylic paint as a solder mask, actually I painted it after
soldering, just to keep the traces from rusting.

I'm printing the masks on inkjet tranparency paper, but I'm having
problems with that because when the ink dryes it craks leaving very
thin lines, in fact I'm surprised that such thin lines remain after
etching. So I have to use a marker to cover the cracks, but still some
remained on the mask and that's what causes those little spikes along
the traces.

I also made a little test of the film as solder mask on a bare PCB,
seems to take the heat quite well. Now I should see if it adheres in
between traces and to the PCB substrate of an etched board.

pixelcanvas wrote:
> I used acrylic paint as a solder mask, actually I painted it after
> soldering, just to keep the traces from rusting.

Invest in a pressure pack of solderable PCB lacquer . It makes rework a 
lot easier, my can is about 10+ years old and I still use it..

> I'm printing the masks on inkjet tranparency paper, but I'm having
> problems with that because when the ink dryes it craks leaving very
> thin lines, in fact I'm surprised that such thin lines remain after
> etching. So I have to use a marker to cover the cracks, but still some
> remained on the mask and that's what causes those little spikes along
> the traces.

You should take photos of your transparency and another of the 
photoresist film directly after development.
Form the shapes of the copper slivers it looks to me you have an 
exposure problem, and not a developer problem.
Developer problems cause either damaged/peeling dry film or an invisible 
resist scum, that inhibits etching in tight corners.
If the ink is cracking then you have the wrong transparency type for 
your inkjet ink. That should never happen.

Adam, by pressure pack of solderable PCB you mean a spray can of
solder mask? I've been looking for that around here but so far I
haven't found any. I've seen it on some websites but I don't think
such a thing can be send by air mail.

As for the slivers, I'm sure it's the little cracks on the ink.
I just took a couple pictures and with the camera macro the cracks
look a lot worse than I thought.... =/
I think is a mix of the wrong film and too much ink on the printer
settings. I think a laser printer should work better.

http://s155.photobucket.com/albums/s282/sawasdee_che/Electronics/?action=view¤t=PCB_Mask.jpg

http://s155.photobucket.com/albums/s282/sawasdee_che/Electronics/?action=view¤t=PCB_1.jpg

Ale

"pixelcanvas" <pixelcanvas@...> writes:
> I think is a mix of the wrong film and too much ink on the printer
> settings.

I'm putting about 3-5 times the "usual" amount of ink down for my
films, and don't have your type of problem.  What ink and film are you
using?

--- In Homebrew_PCBs@yahoogroups.com, DJ Delorie <dj@...> wrote:
>
> 
> "pixelcanvas" <pixelcanvas@...> writes:
> > I think is a mix of the wrong film and too much ink on the printer
> > settings.
> 
> I'm putting about 3-5 times the "usual" amount of ink down for my
> films, and don't have your type of problem.  What ink and film are you
> using?
>

I'm using an Epson printer with original DURABrite Ultra ink. The
tranfarency film is some odd brand I found locally, looks like an
ordinary acetate sheet with a smooth side and a coarse side for
printing, I'll see if I can get a better quality one somewhere.

Ale

"pixelcanvas" <pixelcanvas@...> writes:
> I'm using an Epson printer with original DURABrite Ultra ink. The
> tranfarency film is some odd brand I found locally, looks like an
> ordinary acetate sheet with a smooth side and a coarse side for
> printing, I'll see if I can get a better quality one somewhere.

I'm using an Epson with Claria inks, but on specially treated films
designed for this use.  Look for Jetstar or Silkjet films (I got mine
from vpcinc.com), they have a coating on them that makes the ink dry
ultra fast.  From your photos, I'm guessing the inks "puddled" and
then dried, leading to those types of cracks.  If your films are
coated, you may be printing on the wrong side - use a marker in a
corner to test both sides and see if one is fast-drying.

Failing that, perhaps use an image editing program to only draw the
oulines of those big expanses of black.  It may avoid the cracking
problem, and save you some chemicals too.

> That inkjet printout is horrible. The transparency/ink combination 
> you're using is not working. Pigment inks would most likely cause 
> cracking. Before changing transparencies, try a dye ink instead. Many 
> inkjet printers have pigment black ink for text, and dye ink for photo 
> printing modes. Photo mode black printing is either a dedicated photo 
> black ink or from combined 3 colour inks. In general, I found dye black 
> inks are superior than pigment ink for creating PCB photomasks.
>

For printing I set the colours as full CMYK so it wouldn't be just
black ink, however I´m afraid that my printer doesn't let me use any
other cartridges except the original ones.

I guess the best thing would be, in the future, to buy a laser printer
for this purposes.

pixelcanvas wrote:
> Adam, by pressure pack of solderable PCB you mean a spray can of
> solder mask? 

Its not solder mask because the PCB lacquer can easily be soldered 
through. Solder mask is a type of heat resistant 2 part cured epoxy.

> As for the slivers, I'm sure it's the little cracks on the ink.
> I just took a couple pictures and with the camera macro the cracks
> look a lot worse than I thought.... =/
> I think is a mix of the wrong film and too much ink on the printer
> settings. I think a laser printer should work better.
> 
> http://s155.photobucket.com/albums/s282/sawasdee_che/Electronics/?action=view¤t=PCB_Mask.jpg
> 
> http://s155.photobucket.com/albums/s282/sawasdee_che/Electronics/?action=view¤t=PCB_1.jpg
> 

That inkjet printout is horrible. The transparency/ink combination 
you're using is not working. Pigment inks would most likely cause 
cracking. Before changing transparencies, try a dye ink instead. Many 
inkjet printers have pigment black ink for text, and dye ink for photo 
printing modes. Photo mode black printing is either a dedicated photo 
black ink or from combined 3 colour inks. In general, I found dye black 
inks are superior than pigment ink for creating PCB photomasks.

----- Original Message ----- 

From: "pixelcanvas" <pixelcanvas@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, October 20, 2008 8:13 AM
Subject: [Homebrew_PCBs] Re: Dry film woes, maybe the developer is at fault?



> That inkjet printout is horrible. The transparency/ink combination
> you're using is not working. Pigment inks would most likely cause
> cracking. Before changing transparencies, try a dye ink instead. Many
> inkjet printers have pigment black ink for text, and dye ink for photo
> printing modes. Photo mode black printing is either a dedicated photo
> black ink or from combined 3 colour inks. In general, I found dye black
> inks are superior than pigment ink for creating PCB photomasks.
>

For printing I set the colours as full CMYK so it wouldn't be just
black ink, however I\ufffdm afraid that my printer doesn't let me use any
other cartridges except the original ones.

I guess the best thing would be, in the future, to buy a laser printer
for this purposes.


The cheap HP 5940 DeskJet I use works very well, but needs the more 
expensive JetStar Premium film. I can get down to 5 mil tracks if I need 
them (I never have).

Leon

"pixelcanvas" <pixelcanvas@...> writes:
> For printing I set the colours as full CMYK so it wouldn't be just
> black ink, however I´m afraid that my printer doesn't let me use any
> other cartridges except the original ones.

Edit the picture to be some other color than black, like bright blue.
Then it will print with the color cartridges.  However, find and read
my previous emails about the gimp, coated paper, and ink density.

> I guess the best thing would be, in the future, to buy a laser printer
> for this purposes.

I've tried using my laser printer for photo exposure, and it doesn't
work.  The toner passes UV and the accuracy of the films is very poor
compared to my inkjet.

If you're going to buy a new printer anyway, I've had great results
from the Epson R280 even with just black ink.  I suspect any printer
with Claria inks would do as well, though.  You can buy an R280 from
Amazon for as low as $50.