Box design with a sharpie and PNP?

[lchyi]

Sharpies work with PNP and Ferric Ch right? Could I simply make a design using a sharpie marker and then etch it in Ferric Ch?

[chunks717]

I tried it once, and the sharpie mask did not hold up as well as PnP,
but in theory, sure....if you have PnP, I would try that first..........
I should note that I used half spent FCl, so YMMV.................

[Peter Snowberg]

In my experience, Sharpies work poorly at best. You can get paint pens which work very well, but they're a little sloppy sometimes. PnP will give the best results for detail work.

[Mark Hammer]

Waterproof markers CAN work well, but the problem is that visible "darkness" does not precisely equal degree of etchant resistance.  What can appear too thin is sometimes moe than adequate, and what can appear nice and thick can flake off becaue it hasn't adhered well.  For those reasons, I think the recommendation to go with a transfer system (whether PnP or glossy photo paper) is well-advised.

If resist pen IS pretty much the only reasonable choice you have available to you, then I would suggest the following: use two colours.  Most folks use black because it just "seems right", but realistically the copper and etchant don't care what colour it is, because it is not the pigment that resists the etchant but ratehr the transparent vehicle the pigments are floating in.  This dries and leaves a film.  The colour is simply "evidence" of where it has dried and where it hasn't.

So why two colours?  Simple.  Because laying down two layers assures good thickness and reliable etchant-resistance.  Using two colours will let you know what you have, and what you haven't gone over a second time.  So, one colour for the base (your choice, but black is hard to see other things over), and a second colour for the overcoat.  Sharpies are probably the best-known brand name, and widely available, but many of us have had good luck with Staedtler Lumocolor.

[markm]

Paint will resist the etchant very well.
I usually PNP all the graphics on the top surface and Spray Paint the sides
to resist the etch.
If you prep the whole enclosure to look like chrome using 0000 steel wool,
PNP will stick nicely as will the paint, the nice part is, the paint doesn't stick
as well on the shiny surface so once you're done, the paint mask will come off
quite easily. That's how I've been prepping my boxws for etching lately with
some very satisfying results.
     MM

[BDuguay]

Is it possible that markers in general that don't provide a good coat might be related to the box being dirty?
I would suggest, as it can't hurt, to give the box a good cleaning with naptha, or proponal, or a similar type of cleaning agent.
B.

[markm]

Is it possible that markers in general that don't provide a good coat might be related to the box being dirty?
I would suggest, as it can't hurt, to give the box a good cleaning with naptha, or proponal, or a similar type of cleaning agent.
B.

Not in my experience.
I don't think Sharpie ink adheres as well to aluminum as it does to copper.

[Mark Hammer]

That may be more a property of surface "microtexture" than anything chemical.  The medium in the pens flows very nicely when the copper surface is buffed to a shine, and less effectively when dull.

There is also the unplesant side-effect that small metal particles can erode off the box/copper and lodge in the tip of the pen.  The pen tip may SEEM harmless but it is really a sort of microabrasive.  That is likely why buffing/polishing helps with flow - if thepen doesn't "catch" then there is likely to be less particle buildup in the tip blocking ink flow.

[markm]

That does make sense Mark.
I will confess to using Sharpes to fix "boo-boos" in some of my transfers.
Works well but, still not as durable as PNP it seems.
    MM

[Paul Perry (Frostwave)]

I wonder whether 'whiteout' or other correction fluid works?

[Mark Hammer]

There are a LOT of things that will "work", including correction fluid.  The big challenge is how long they will work.  If you have: a) copper board so shiny you can see your razor stubble in it, b) fresh etchant, straight from the bottle, c) a means of keeping the etchant warm, d) a gentle bubbler or other sort of etchant "energizer", and e) a board which is modestly sized, with plenty of clean space between traces and big whomping pads, then the etch can proceed and finish very fast.  You could probably used dried ketchup as resist in such an instance.  As the number of things that slow down an etch add up in number, the requirement to have something that maintains its adhesion and water-resistance against all odds, becomes that much more important.

Heat transfers that literally fuse with the copper are clearly good for hour-long soaks.  So are photosensitive emulsions on the board, and waterproof pens hold pretty well for half an hour and often more.  Correction fluid might begin to flake sooner than pen would, but shold hang in there for a while.  I might point out that one ancient article from Popular Electronics that I saw decades ago (just after it broke away from "Popular Kite Flying" ), illustrated a method involving cutting a template from stiff paper with a fine-tipped utility knife, and painting on nail polish or some similar lacquer-like finish.  Like I say, there are a lot of things that will work.  The trick is finding things that work under the circumstances you need them to work under.