Experiments in Etching.

[Onoff]

@bigegg , etching copper with ferric chloride.....

Used to do it for PCBs a lot, as a kid. Started drawing on plain copper with a Dalo pen, all freehand. Permanent markers were good too and cheaper. Moved onto rub down transfers. Tried the one you printed onto a sheet that you ironed onto plain copper PCB.

Then I got a UV light box. From memory I'd print onto clear sheet, expose in the light box, place in developer then etch.

I've got SWMBO off looking for the light box she "moved" recently. Just for a play I was going to overlay one of the pub prints onto some photo resist board I have here and see what result I get.

What I'm interested in is how you do it on solid copper sheet. How do you protect the back side of the copper sheet whilst it's in the etch tank?

Cheers

 

[bigegg]

@bigegg , etching copper with ferric chloride.....

Used to do it for PCBs a lot, as a kid. Started drawing on plain copper with a Dalo pen, all freehand. Permanent markers were good too and cheaper. Moved onto rub down transfers. Tried the one you printed onto a sheet that you ironed onto plain copper PCB.

Then I got a UV light box. From memory I'd print onto clear sheet, expose in the light box, place in developer then etch.

I've got SWMBO off looking for the light box she "moved" recently. Just for a play I was going to overlay one of the pub prints onto some photo resist board I have here and see what result I get.

View attachment 321271

View attachment 321272

What I'm interested in is how you do it on solid copper sheet. How do you protect the back side of the copper sheet whilst it's in the etch tank?

Cheers

Spray it with b&m turner+grey primer.
or self adhesive vinyl - or even sellotape

 

[Onoff]

Found the light box!

Gave it 1 minute exposure. No pattern apparent, should there be? Tried another minute.

2 minutes, still couldn't see a pattern, so thought sod it and chucked into developer. Rinsed and into a ferric chloride substitute, sodium persulfate.

Now rocking gently in an ice cream tub atop the oil boiler with some 6013 "rollers":

 

[Onoff]

Not bad for a first attempt. For this I just took the original photo and changed to grey scale in Paint Shop Pro. Shows up quite well with a light behind, like a lithophane.

 

[Onoff]

@bigegg , evening. I was going to have a go at etching brass sheet. So far I've cleaned the brass with IPA and coated one side with Turner & Grey primer. (Brass was leftover from a sheet of I think 1mm I'd made a special gland plate out of):

Plan is to then spray the opposite, bare brass side with this:

Then overlay a transparency and expose in my UV box.

Do you reckon this ferric chloride substitute, sodium persulfate I have will etch the brass like it does copper?

 

[bigegg]

@bigegg , evening. I was going to have a go at etching brass sheet. So far I've cleaned the brass with IPA and coated one side with Turner & Grey primer. (Brass was leftover from a sheet of I think 1mm I'd made a special gland plate out of):

View attachment 322835

Plan is to then spray the opposite, bare brass side with this:

View attachment 322836

Then overlay a transparency and expose in my UV box.

Do you reckon this ferric chloride substitute, sodium persulfate I have will etch the brass like it does copper?

I'm afraid I have no idea: I've never etched brass. Google should provide some info...

<edit: A quick search suggests it will work. But I would point you towards the title of this thread...>

 

[Onoff]

I'm afraid I have no idea: I've never etched brass. Google should provide some info...

<edit: A quick search suggests it will work. But I would point you towards the title of this thread...>

I shall experiment and report back!

 

[Onoff]

So that can of Positive 20, pic above repeated here. Says on the back you can dry the sprayed board at 70degC for 15 mins. Looks like I'll be firing up the oven!

Off to find a nice photo for the transparency now.

 

[Onoff]

Think I screwed up a bit. Some repeat comments for completeness. So I had my 1mm brass sheet and I sprayed one side with B&M grey primer (the Turner & Grey make). I let that dry, turned it over and sprayed with Positiv 20. Then placed in the oven at 70degC for 15 minutes.

2 problems so far:

The brass face I sprayed the Positiv 20 onto, I'd only cleaned with IPA. The photo resist spray went on with a few pinholes where it didn't stick to the brass. Thinking I should lightly abrade it first next time I do this. Worst thing is the Positive 20 bled round onto the B&M grey primer and took it off.

The Positiv 20 after drying for 15 mins at 70degC. (I laid it on a sheet of greaseproof paper on a baking tray). So the brass now has a "grey" film on it:

This, the grey primed side where the Positiv 20 bled round and took it off.

Word of warning, Positiv 20 stinks like pi$$! I've had to light a scented candle in the kitchen.

Now at this stage, with a perhaps less than perfect photo resist side and a definitely damaged primed side, I should perhaps be taking it all off and starting again...

Impulsive sod that I am I've just hit the area where the primer has come off with a bit more and am letting that dry.

Then it's light box and etch!

 

[Onoff]

Maybe I should stick vinyl one side and run a permanent marker round the edge like @bigegg does? Or apply the Positiv 20 first then prime afterwards.

 

[Onoff]

Maybe I should just apply vinyl one side and run a permanent marker around the edge like I think @bigegg does? Or apply the Positiv 20 first then prime the other side.....or use etch primer rather than the B&M stuff.....

 

[Onoff]

Right then, fingers crossed!

The repaired primer seemed dry enough so it was off to the UV box.

2 1/2 minutes exposure seemed to give a pretty good image. This after developing in sodium hydroxide:

Warming the sodium persulfate etching fluid in a bowl of hot water:

Into the warmed etching fluid:

No ideas how long it'll take in relation to the copper clad PCBs I'm used to.

 

[Onoff]

Hmmm...the sodium persulfate was taking an age to etch the brass seemingly. It was working but oh so slowly. So after an hour I poured it back into its container and dug out some ancient ferric chloride that's sat in the old stable for I guess 20 years or more in an old, unmarked lemonade bottle.

Seems to be etching a bit quicker. The question is when to stop? Long enough for the picture to have depth but not too long that it loses detail?

 

[Onoff]

Seems to have potential I guess. I had to take it out of the etch as I was losing definition around the windows and cills. There's a definite raised effect though overall. The "sky" around the roof didn't erode too well.

What's weird is where it's eroded the brass it appears to have deposited copper? Didn't want that, I wanted to see brass.

It might have gone better & quicker perhaps, with less loss of definition, with fresh ferric chloride.

Just rinsed and cleaned with some CIF on a plastic scourer. Maybe try Brasso? I think the "black" areas may be photo resist still on there. Lose that and I'll lose even more definition!

 

[Onoff]

Work in progress I think!

The copper deposits, maybe from the exhausted old ferric chloride?

Typically I went looking for Brasso in the garage and found 1kg of new ferric chloride crystals! The Brasso at least takes the copper deposits off.

I still need to trim it smaller to the size of the original picture.

 

[Newlands]

It’s probably etched out the zinc in the brass, leaving the copper behind.

 

[Onoff]

Looking now I should have perhaps left it in the developing solution a bit longer. Above the roof line looks a bit "protected" still by photo resist. Left in a bit longer might have produced better definition in that area.

Cut to size Brasso'd and washed:

 

[Onoff]

I've no more brass sheet here. Do have a big bit of 1mm copper meant for the 3D battery adapters.

Might have a play with that and fresh ferric chloride.

 

[Onoff]

Thinking to "re-mask" areas then re-etch to get better definition on the roof. I could I guess just spray the finished article with Positiv 20 again and re expose to UV using the light box. I really, really want though, to preserve certain high points without any more etching taking place.

@bigegg did you say you use a Sharpie pen as etch resist? I used to used Dacron Dalo pens back in the day then various permanent markers...Papermate, Pentel? Too long ago, like 40+ years!

Was thinking to get my youngest who's a dab hand at "art" to go over all the high points with a resist pen then re-etch. At the same time she could bring the roof out.

I also want to put the pub name and address on the reverse.

I may have an old Press 'n Peel iron on PCB transfer kit somewhere in the loft...

 

[selectedgrub]

The preservation and persistence is admirable.
Thanks for sharing.