Soaking and cleaning

Now you have your paper well and truly ironed on to your copper board it’s time to get rid of the paper so we can etch the thing.

Get your self a plastic tub large enough to fit your board flat on the bottom, but not so large as we’ll use it later for etching and there’s no need to use more chemicals than necessary.

Boil the kettle and fill the tub halfway and give it a squirt of washing up liquid. Drop the board still hot directly into the tub and leave it for a minute or so to soak.

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After a minute or so you should see the paper wrinkle up as it starts to absorb the water.

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Paper wrinkles up. You’ll be able to see the circuit
pattern where it is attached to the copper.

Take the board out of the water and rub the paper side gently with your thumbs. If everything is going well the paper should start to fall apart in your hands and whilst hopefully leaving the toner firmly attached to the copper.

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With a bit of gentle rubbing the paper starts to fall off in strips.
The magazine paper falls apart in two layers.

Return the board to the water for another good soak, you can change the water if you feel like it. Then repeat the process until you’re almost clear of paper.

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Back to the water.
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Getting there.
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Almost
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Scrub it clean.

Feel free to use a tooth brush, fingernails or even the scrubby sponge thing from earlier on. If all is has gone well then the toner should be so well bonded to the board that it actually takes quite a lot of effort to remove it physically.

It is at this stage where you should be able to see how well the whole process has gone. If it went well you should have a clearly defined toner image on your board. If not then you’ll need to clean the board off and start again. Look for tell tale signs like a finger print shaped missing patch to see if it was down to a greasy board or maybe not enough scrubbing earlier on. Use a bit of thinners to clean up the board and start afresh with a new printout. Assuming that you want to carry on that is…

Anyway, I trusting that all went well there will probably be a small amount of paper still attached to the back of the toner (It’ll be white when dry) but as long as it’s not blocking areas you need to etch it doesn’t really matter.

You’ll be bound to get a few areas where it didn’t quite work, but they can be fixed with the use of a handy permanent marker. Americans go on about “Sharpies”, I don’t know what they are but I would guess that any kind of truly permanent marker will do.

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This pen works great in the chemicals I use.
You’ll need to test yours to be sure.

I tend to get a bit carried away when touching up the toner with the pen.
Once you dunk your board in the etch solution you can’t really go back. So I figure that as I’ve gotten this far, five minutes extra spent blacking in any suspect traces is well spent to get a decent board.

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Small bits of paper remain, but it doesn’t matter. You can see a bit of
missing track near the middle on the image.
Sorry about the blurry photo.
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A bit of touching up with the permanent marker.
More than is need really, but better safe than sorry.

Now we are ready for the next stage. Etching the board!

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2 thoughts on “Soaking and cleaning

  1. Hi – great article, thanks!
    Regards the touching up with a pen, did you have problems drawing over the toner?
    When I tried this, the toner seemed to have a shiny coat that made the pen’s ink ball up and run off…

  2. Hi Stephen.
    I would guess it’s down to the liquid used in the pen’s ink. I used a fast drying black TDK CD-R pen that I think is alcohol based. It seemed to quite like the toner and soak in quite well with no balling or run off. Sometimes I had to draw over the top a couple of times to make sure there was coverage, but even where it looked a bit thin it worked just fine.
    It might be an idea to try buy yourself some different pens and see if they give you better results.

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