crashsite

It's been the norm for decades that business and educational presentations use the overhead (also called, transparency or VU-Graph) projector. A common accessory to the overhead projector is clear film that is specially designed to accept images from a photocopier or laser printer.

But, I fear the days of the overhead projector are numbered. The digital projector is a superior alternative in virtually all aspects. In fact, I think it's only due to the mental inertia of folks who just don't want to give up the old ways that keep overheads around.

But, the day is surely coming when the overhead projector and the transparency sheets will go the way of the buggy whip. When that happens, a product that is now readily available will become difficult to find.

I mention this because the overhead transparency sheets have uses beyond presentations. Uses that relate to building electronic projects.

PS: Sorry for not mentioning the transparency sheets in the title. I was planning to go back and add either that or something about Colormaze and then got sidetracked and...well...didn't. Once posted, the text can be edited but, not the title..

Many people have tried to use the overhead transparency sheets as a mask for making printed circuit boards and silkscreens. Virtually always with poor to marginal results. That black toner on the clear background looks nice and dense but, the toner is actually quite transparent and lets a lot of the light through to expose parts of the photoresist or emulsion that are supposed to be masked.

But, there is a product (no, I don't sell it) that makes the transparency sheets a lot more practical for those photo processes. It lays down a metalic foil onto the toner, making it quite opaque. It's called, Colormaze from a company called, Admaze (which sells the stuff and also refills toner cartridges).

Anyway, the warning. I think people who are interested in electronic projects would do well to "stock up" on the transparency sheets while they are still readily available. In fact, as the digital projectors become more and more popular, there will probably be a period where the transparency sheets will become easily available and may even be discarded as trash by the companies you are working for in the next couple of years.

I know there's nothing to respond to in this post but, if you know of additional uses for the transparency sheets as applies to electronic projects, please add your thoughts.

dknguyen

Use it as an overlay so you can scribble all over your schematics but still see what it was that you printed out.

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jpanhalt

Transparencies are used also as an art medium in their own right. Check out Pictorico.com

As for Colormaze, have you used that on the transparency, or after transfer of the toner (via paper) to the PCB? If on the transparency, at what temp do you iron it?

John

crashsite

Yes, I have used Colormaze on transparencies and it works well. I usually use the solid red under the assumption (not tested or proven) that UV light leaking through the red foil will attenuated more than if other colors were used.

I've thought about trying to apply the foil to the toner after it's applied to the PCB, to beef up the resist layer, but have never tried it and suspect it would be more of a problem than a solution.

I usually use the Colormaze with an iron (household with teflon), rather than running the sheet through the printer or copier again as recommended by Admaze. I have my iron set to about 300F (per a non-contact thermometer) for all transfers (toner to PCB and Colormaze to toner). As a side note, it's easy to get a temp reading when the iron has a teflon surface but, difficult if it's shiny steel.

Also, I like the suggestion about the overlay for schematics although, for that purpose, cheaper clear cellophane or celuloid would probably be more cost effective since the transparency sheets are not real cheap.

KMoffett

crashsite,

Do you have any links to Colormaze or Admaze or vendors. Google links about Colormaze to Admaze.com no longer exist. Looks like Colormaze may have beaten transparencies in an early demise.



Ken

Ken

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jpanhalt

I don't have Colormaze, but I suspect the film is very similar, if not identical to the GreenTRF sold by Pulsar (http://www.pulsarprofx.com/.

John

mike50

"Virtually always with poor to marginal results" ???

I use a laser printer to print PCB masks on transparencies all the time and have always had perfect results. I've also used tracing paper and that works nicely too - you just need a longer exposure.

Mike

crashsite

Well, I'll be gosh darned diddly damned!!! I ordered a box of Colormaze (assorted) for one of my nieces who is into graphics and also a couple of bottles of toner for my and my mother's Samsung laser printers just a few weeks ago and had their web page up just a few days ago. I see that the URL has been taken over by a new outfit and there's a note that Admaz's domain expired on the 8th.

Since I have some of their product here, I was able to call them on the phone and they were unaware that there was a problem with their domain. The company is in San Jose, CA and their phone is 408 441 9920. Hopefully, they will be able to get their domain name back but...maybe not since there is another company now using it.

I've had good luck with the company and have found them to be very easy to work with and also good luck with their toner (which they are willing to sell by the bottle even though their business is refurbing the carts) and the Colormaze. I'll keep an eye on this situation and will post an update when things get back on track.

As the old saying goes..."Timing is everything".

BTW: A packet of Colormaze is $20 + shipping and that's 20, 8.5 X 11 sheets. One nice thing about the Colormaze is that only what sticks to toner becomes unavailable. That means that you can keep using unused areas over and over until there's just not enough foil left to be useful. If making small projects one package will probably last for years.

crashsite

What they are calling a "decal" looks like it might be a product similar to the Colormaze. I don't ahve any experience with it, however.

crashsite

You're a better man than I am, Gunga Din! Over the years I've used just about every medium and substrate (including paints, felt pens, toners, vellum, plastics, photographic film, etc.) and, have always had iffy and inconsistent results.

I've used many different light sources from the sun to sunlamps to what I usually use these days: An old Diazo box (uses UV flourescent tubes which are, unfortunately not a point source, but work pretty well). I used to work for a school district and got a bunch of the boxes in a disposal sale. Hmmmm...maybel I should put them on E-Bay...

jpanhalt

Are we talking about the same thing? I am referring to the GreenTRF, not the Pulsar Toner transfer paper.

The Green TRF is metallic and sticks to the toner, not to the board.
That's what I want to do. I use the positive photo method and would like to be able to use my laser printer to make the transparency.

At what temperature/iron setting do you apply the Colormaze?

John

crashsite

[quote=jpanhalt]Are we talking about the same thing? I am referring to the GreenTRF, not the Pulsar Toner transfer paper.

You're too quick for me. I went back an revisited your link and edited my previous post but, you were writing yours at the same time! From the description, it sounds very similar to the Colormaze. But, I've had such good luck with the Colormaze and still have quite a bit left so, will stick with it for the time being.

The Admaze people envision sending the paper (or transparency), layered with the Colormaze sheet, back throuth the printer or copier with a blank page just to run the product across the fuser. They use what I consider to be a somewhat rinkydink system of adhesive dots to hold down the Colormaze. I use an iron externally. My iron is about 300F (see a few posts up for more detail).

jpanhalt

Thanks for the temperature. Sorry about the cross post. I have no problem with sticking with what works. I happen to have some Green TRF on hand and was thinking of using it against a laser transparency the next time I make a board, as my favorite transparency for ink jet is effectively no longer available. You saved me doing some experiments. And so, I will move forward with confidence. If it works, I will post back here.

John

Dean Huster

Document cameras are the norm at the community college where I teach. I can't think of any disadvantages of them over the older overhead projectors. They're smaller, have zoom capability, all kinds of digital enhancements and have a "negative" switch that will allow you to place color transparancy negatives on the platen and view them as positives -- really an odd feature on a digital system that provides for viewing film that is quickly being replace by digital cameras!

With the document camera, you can use regular televisions, feeds to students' laptops, have integration into "distance learning" transmissions, projection TV with the standard screen, etc. I still occasionally use the transparancy film with the opaque images as overlays where I can use the standard transparency marking pens to write over a book diagram without messing up the book or having to make copies of the page (usually an unwanted color-to-monochrome transistion).

The old stuff in the classroom is gradually being shoved aside. My biggest concern in the move to "smart boards" vs. the standard chalk boards or even white boards with the always drying-out erasable markers. I think the expense of the smart boards is sinfully wasteful for what you get.

Dean

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jpanhalt

I am with you on that opinion. The digital stuff is nice, even better in many instances. We did not have a digital projection camera for overheads (I still like to draw things), but I could survive with only a laptop and a chalk board. It is great the old 2X2 Kodachromes are gone. Problem is that I have a few thousand of them. You can always tell the scanned digital image from the original.

I detest the white boards. They are messier, and the pens are always dried out. I had my own set for that very reason, but chalk wipes off your hands, ties, etc. easier. John