Etching hints from veterans?

[italianguy63]

Well, I did my 1st couple of etches this weekend.. and I had pretty good success.  Learned some things and have some questions.

Paper:  Had some cheap glossy stuff, and I don't know what brand.  Worked great!  But, I am out.  Had some Kodak brand paper, and although it is good, it is "plasticy" and requires a good amount of soaking to get off.  I went to Office Depot, and bought their store brand.  Total no-go.  Totally plastic.  I can iron it on the enclosure, but no amount of soaking would free it-- I had to sand it off!  Does anybody have a particular brand they really like?  I would think high-gloss with a paper (not plastic) backing would be best.

Extra toner:  Has anyone played with settings on the computer to dump more toner on the print?  I found a "print density" setting, but it does not seem to do much.  Is it even possible to run the print though a printer twice, doubling the amount of toner?  (I would think you couldn't get the alignment perfect and it won't work).  I may try tonight.

Pitting:  I did 2 etches.  First one came out good  (about a 8 out of 10), but I had a good amount of pitting in areas I did not want it.  I did notice where I used nail polish to touch up imperfections, it was perfectly clear.  I can do that, but it seems a pain, and I can't get too close to intricate details.  On the 2nd etch, I used a "paint pencil" instead of nail polish with good results.  Easy to control, and had good coverage.  But again, I had too much pitting around my desired etch-- which leads me to the next, and main question  (2nd one although clearer had more overall un-desireable pitting and about a 5 out of 10).

How much is too much etch:  I think this is my problem.  I think I may be overdoing it.  I am trying to get "depth" but my etch had a lot of intricate detail.  I think I am overexposing, and eating through the mask.  How do you know when enough is enough?  I have been etching enough to get depth, but when I try to clean up the pitting, I end up ruining the deep etch, and start to loose detail (by sanding).  I am wondering if maybe less etch is what I want-- letting the etch "patina" be the design, and not so much the "depth."  God knows you can't sand the patina off.  Is the etch patina really adequate, especially if you are not going to fill the voids with colored paint?

I assume if I was doing a less detailed etch with bigger elements, it would not be as much an issue.  I think I am trying too hard to get deep etch on small details and lettering.  Does anyone have some pointers or a guide as to how to gauge when enough is enough??

Sanding:  Is there an easy way?

MC

[Maik]

Hi,

what do you use for etching? More aressive acid is better for less underetching (that makes thin lines big), aluminium is bad to etch and the lines are going to be fat instead of going into deep. Better have a look what I mean, cause english is not my native language.Post 4 is what I mean.
http://forum.mungolux.com/viewtopic.php?f=4&t=975&sid=a639f0232c06f3b92cd745c304134140
For etching I use HCL and H2O2 and water 1:1:1. That is very agressive and etching needs 1-2min.
Deep: nearly 1mm deep is ok for big lines but you get rid off thin lines (they are goinig to get bigger then). Thin lines need a short time of etching.
For the sanding I use a beltsander first and the rest (to get a plain surface) by hand.
How do you make pcb`s? With uv-light or with the tonermethod? With uv-light and an uv aerosol it´s easyer to get a closed surface.

[bukas]

i use faststone image viewer to adjust contrast and gamma of layout before printing. just make it totally black to avoid less toner on some pixels, or use paint xD it has nice zoom in. and i like to fill holes to.

[Mark Hammer]

Remember that your etchant bath does not distinguish between etching vertically or horizontally.  It just eats what is adjacent to it.  The mask you lay down on the surface addresses "vertical" etching by covering the surface.  But it does not overlap the sides of the areas that have been etched away, and protect them.  If you need to leave the item in the bath for a longer period, the etchant begins to eat away sideways.

In this very crude drawing below, the asterisks are the toner mask, and the solid line is the copper.  Once the etchant has gone down below the level of the toner, it starts to work sideways.

****        ****
____<-->____

I've always found the trick is to do what you can to facilitate as quick an etch as possible.  That can involve (but is not restricted to): making sure the surface is scrupulously clean, having the bath warm, and not using any given etchant bath too many times.

[Maik]

Thanks Mark, this is what I want to say with "underetching"

[poppyman]

I found that the temperature of the etchant is a very important factor. I do my etching outdoors and I usually put my Ferric chloride tray in a larger tray filled with warm/hot water when the weather is cold. It dramatically speeds up the etching.

[Maik]

every 10 degrees acid doubles it´s power.
With HCL+H2O2 and water 1:1:1 at 35 degrees it took 1min to etch 1mm deep

[italianguy63]

I was using HCL and 40% H2O2 (no water).  Certainly works fast... The enclosure gets hot to the touch. 

I was going about 5 minutes.  It looks like I have been etching too long.

[Maik]

Far too long! Ha d it also once. 2min and very deep etch
It went to the trash
Normaly HCL has also 33%.
How much of HCL and how much H2O2?

[italianguy63]

50/50 mix -- I'm going to try to get around to doing another this afternoon, and reduce the etch time.  Hopefully it will come out good enough to post a pic.  (I probably just jixned myself - damnit!)

[deadastronaut]

I found that the temperature of the etchant is a very important factor. I do my etching outdoors and I usually put my Ferric chloride tray in a larger tray filled with warm/hot water when the weather is cold. It dramatically speeds up the etching.

yep, it likes to be warm,

i put ferric granules in the tub and pour in warm-hot water..mix, then put that tub into a larger tub with hot...this time of year it cools quickly.

i place the face into the ferric and pull it out and put it back in ...when i see bubbles at the side of the box, thats when i pull it out and put it back in many times.....

this lets the box react and fizz, and ferric foam runs off it......and eventually a small ridge will appear where it has been dissolved away..

repeat many times till exposed areas are totally black...and the reaction has slowed/cooled...then its toothbrush under cold water time...with a little soap.

sand ...paint fill.....fine sand..done.

[italianguy63]

To be more specific-- the HCL is pool acid (32%)
and the H2O2 is hair salon bleach (40%)
50/50 mix -- no water added.  Works very fast!

[italianguy63]

I was definitely "overcooking."  Got decent results this time around!  Only about 2 minutes.  

[mmlee]

What do people do with their chemicals once they're not etching anymore? Dump?

[Maik]

Mix it 1:0.5:1  HCL:H2O2:water
You don´t need 50% H2O2, it´s only a catalysator. When etching is too slow take more H2O2. But you need some water. That will spread the etchingtime and it will be easyer to control the etching.
My H2O2 is about 30%, HCL is 33% and I do it with a mix of ca 0,75:1:1 and the mix is around 20°C. Don´t make the mix too strong, you can`t control the time. But if you make the mix too slow you will get underetching.
When you mix the acid with water: fill water in FIRST or the acid will grab your face. HCL turns out very agressive when puting water in it!!!!
Hands will look this way after beeing stupid
https://app.box.com/s/xp4nltxm6sxxh8pronuc
So take care and allways wear handgloves and savetyglasses!!!

@mmlee
I put it in the loo-always clean and no lime.

[italianguy63]

Ouch!  Thanks for the info!

What do people do with their chemicals once they're not etching anymore? Dump?

Goes good with vodka and anti-freeze.  Takes away the sweetness of the anti-freeze.  (Kids:  It's a joke!  Don't do it.)

MC

[italianguy63]

I did notice, that once I would rinse, and look at the progress... I could see parts of the mask start to "lift" and bubble.  that was when I quit.

[deadastronaut]

^ try sanding with a coarser grade paper to give it more 'grip' .

i use 180 grade, then iron on toner...then when etched use a finer paper , i like the brushed aluminium look , so i stick with coarse, just my preference...

this one was clearcoated after....which i have stopped doing now...i prefer it as raw metal nowadays

[italianguy63]

Thanks Rob--

I did this one really fast, and did not take the time with the prep. I should have.  Now that I am on the right track, I can do better.  If you look close, you can see clean "tracks" where I went around the design with the paint pencil (leaving areas that ended up getting some pitting).  I also did the prep sanding fast with some 320 wet/dry paper.  I have had better luck using and automotive DA with some 180 grit on it-- the stock paper dulls really fast on the metal-- ends up working well.  For cleanup, I don't have it figured out yet.  I have a mini-sander from Harbor Freight that lets me go after the imperfections-- but once that is done, I don't know what is best for final finish.  I am thinking like the 320 wet/dry (sanding in one direction, up/down, as you say for the brushed aluminum look).  I would think you could go to 400 and some compound for a polished look if the etches are good enough....

[deadastronaut]

yeah, you can buff them up to look like chrome if you go finer and finer...and then use a polisher.

btw i use plenty of nail varnish around it and i check under a lamp for any tiny little specks where the toner may have not covered thick enough....i can't stand the pitting around my image so i get pretty anal

about it...but i end up more happy with results.

but, yes, its ALL in the prep for sure.


i'm doing an etched box for a member here later...i'll take some pics, etc..