Etching boxes using 'brush on' method - report

[gez]

Last year I mooted the idea of using transfers to etch aluminium boxes, brushing on ferric instead of immersing it in acid.  I finally got round to trying this and it definitely has possibilities.  The end result looks as though it’s been professionally engraved - very nice!  I’ve only tested it on the bottom of an unfinished box and haven’t done it ‘for real’, but, with a little work, this might be a useful lettering method.  It’s safe to do inside too, no fizzing/fumes etc.

After applying ordinary dry transfers I cordoned off the area around the lettering using sticky back plastic so that it formed a square, then liberally applied the ferric using a brush-shaped sponge on a wooden stick which I bought from my local art shop.  The ferric forms a little pool and gently etches away.

There’s no depth to the finished lettering at all, but that’s partly because I didn’t leave it to etch long enough (despite leaving it 1 and a half hours!).  As is, it looks incredibly professional, but the lack of depth means that it’s difficult to see in some light (definitely a problem).  Although I can’t say for sure, I should imagine that this would be resolved by leaving it to etch for longer - I’ll do some more testing next week and report back.  I don’t have a camera so I can’t post pics I’m afraid.

One of the electronic suppliers I use sells spray on photo resist.  Haven’t tried it, but I don’t see why one couldn’t spray a box with this stuff, lay over a transparency of your art work, then expose the box to UV light.  This would allow for more creative lettering/designs.

Incidentally, you can use fluorescent lights (I use the one in my kitchen) with photo board.  Just tape a transparency to your board, then tape the whole lot to the surface of your strip light (use masking tape so that you can reuse the transparency).  The board I use supposedly takes 8-15mins using a UV box, and I find that 15mins or so works fine with a fluorescent light, so I should think that if you choose the longest time quoted for the board you buy (plus some maybe?) then you should be alright.  Again, I don’t see why you couldn’t do this with a aluminium box.

If any of you try any of the above, be sure to test it on scrap first to see whether it’s suitable for your needs.

[gez]

Wow!  Found some time today and tried some more samples, leaving the ferric on for longer than I did yesterday, and the results are superb!  

Five hours is the best result so far.  It would probably look better with six or more, but maybe the detail would start to go?  There’s still virtually no depth, but when running a finger over the surface a slight dip can be felt.  Any exposed metal becomes discoloured, so with transfers you’re left with plainly visible shiny lettering that has an engraved look to it, surrounded by a darkened square.  

I think the way forward with this approach is to use photo-resist on top of the box, overlay a transparency with clear lettering and a black surround, then expose, develop and etch.  This would leave dark, slightly indented lettering on a light box.

I’m definitely going to do some boxes using this method!

[smoguzbenjamin]

Sounds cool, gez. Do you have any pics or is the effect so light that it's not really precievable with a camera?

[gez]

PS.  I used a prermenant marker to make the square surrounding the lettering, then overlaid some sticky-back plastic.  Yesterday there was some undercut just using the plastic on its own.

[gez]

Sounds cool, gez. Do you have any pics or is the effect so light that it's not really precievable with a camera?

There's no problem at all perceiving the lettering with the longer etch time, and it would photograph well, I just don't have a camera...sorry!

[smoguzbenjamin]

never mind, sounds like a real cool thing to mess around with! Like sunk-in letters and stuff

[sfr]

Could you bring out the lettering by applying a bit of paint or metal antiqueing stuff, and then lightly rubbing it off with a dry paper towel, so it only stays in the recessed etched bits?  I've done things like this before to give a bit of an aged patina look to engraved silver jewelry, and works relatively well, even when the depth of the details isn't too much.

[puretube]

the stuff you develop photo-sensitive PCBs in, or use for "cleaning" drain-pipes, is a wonderful etchant for aluminum. (NaOH or NaOh2 ?)
50deg C, (in well ventilated area), 10 minutes...

Caution: it is, of course very aggresive to You, and a lot of materials...

[gez]

Could you bring out the lettering by applying a bit of paint or metal antiqueing stuff, and then lightly rubbing it off with a dry paper towel, so it only stays in the recessed etched bits?  I've done things like this before to give a bit of an aged patina look to engraved silver jewelry, and works relatively well, even when the depth of the details isn't too much.

There’s hardly any depth so I’m not sure that would work, but any metal that’s exposed to the ferric turns a dark grey colour (if etched long enough) so there’s enough of a contrast to see the lettering clearly.  

Using photo resist and a transparency would give dark coloured lettering on a light box.  The thing that impresses me most with this method is the detail.  I’ve used italic transfers and every detail (even the hair-line parts of each character) has been captured.

[Jason Stout]

This post reminds me of the time I etched a Hammond box with USED ferric chloride. I used Ansil's? idea of pouring ferric onto the box with a paper towel draped over it, this was all in a plastic tub. I did this outside in 20 degree Fahrenheit temperatures with little or no immediate reaction. I moved inside, and prepared a hot water bath, placed the tub into the bath, and watched a violent reaction take place. I stopped the reaction after about one minute with baking soda. After I cleaned the box, I noticed that my resist had not worked; I also noticed that the reaction with the used ferric chloride plated copper onto the surface of the box in a few areas.



The copper plating is not apparent in this picture, I think it is on the side, or inside. I'll try to take a picture of the copper.

Gez, I think your method is a prime candidate for used ferric chloride!

[gez]

the stuff you develop photo-sensitive PCBs in, or use for "cleaning" drain-pipes, is a wonderful etchant for aluminum. (NaOH or NaOh2 ?)
50deg C, (in well ventilated area), 10 minutes...

Caution: it is, of course very aggresive to You, and a lot of materials...

Yeah I know, but the common complaint is that it etches too fast so it's difficult to get any fine detail.  I gather that it's not something to be done inside either due to the fumes etc, whereas the ferric method I mentioned above is totally safe (important to me as I live in a third floor flat and don't have access to a garden/yard).

[gez]

The copper plating is not apparent in this picture, I think it is on the side, or inside. I'll try to take a picture of the copper.

Gez, I think your method is a prime candidate for used ferric chloride!

That sound really cool!  If you can, please post a pic.  The etch time would be a lot more of course, but it sounds like it's worth it!!!

[Jason Stout]

Gez, something to think about, your reaction will become violent if you intentionally or unintentionally apply heat. I wasn’t fully expecting the amount reaction I got!

Got any pictures?

[Jason Stout]

I'll be back...With pictures.

[gez]

Sadly, I don't have a camera so I can't post pics (wish I could!).  

Just creating a little brushed-on pool of ferric doesn't give any violent reaction, it just looks a little frothy after a while but that's about it.

[Jason Stout]

O.k. Here it is.

[gez]

If I could get the lettering to look copper coloured using the photo resist idea I mentioned, then that would be really cool!

The developer I use is one of the 'safer' types which is sodium hydroxide free.  It has no effect on aluminium at all (I tried it this morning) so it should be suitable for my purposes.

I've been tied up messing around making PCBs recently so won't get round to trying this until two or three weeks time, but I'll report back when I do.  If it's any good I'll see if someone I know has got a camera I could borrow.

[Jason Stout]

If you ever need a picture posted, just send it to me

[gez]

I’m in the middle of doing the graphics for a photo resist etch, but here’s a pic of the tests I did when I first posted this thread.  I spent little time on getting the transfers lined up or on squaring up the ‘boxes’, so bear that in mind.  

The darker ones had longer etch times.