Re: poor man's decal

We have our boxes anodized and laser the artwork. That's so much easier than making labels.

For prototypes or one-offs, I print in mirror-image on an overhead projector acetate sheet using a laser printer. The print side is then spray-painted white (several very thin coats, allowed to dry between coats, so as not to dissolve the printing) and stuck to the panel with double-sided sticky tape.

The unprinted acetate surface is fairly durable and the print side is towards the panel, so it can't be scuffed off.

If you need to change it, the sticky residue from the tape can be removed with white spirit or petrol.

There are now some very impressive UV-cured colour inkjet printers intended for printing onto aluminium and plastic panels and boxes. I saw some spectacular examples at an exhibition recently. They were boxes supplied by Hammond. The printing seemed very durable and the colours were very striking. Resolution looked much better than silk screened panels. John

It looks like the silk layer on PC boards is not silkscreened any more, it's inkjet printed. 50 or even 40 mil ref designators are legible.

Usually the entire surface and a bit beyond, then trim off the excess.

My experience has been that the weakest bond is between the print and the acetate sheet. Pulling the acetate sheet from a corner leaves a lot of the paint and print on the sticky tape; some of the tape can be removed mechanically and the rest comes off with solvent.

On double-sided sticky tape it will - your biggest problem will be getting it lined up before it sticks in the wrong place. I have two methods:

Once it has stuck, any attempt to reposition it or remove any air bubbles will probably finish up tearing the print off the back.

True, but i have known these acetate labels to survive nearly 5 years outdoors on a south-facing wall (in English weather, which is not the severest of UV tests).

The acetate sheet can be ripped off, so the solvent attacks the sticky stuff fairly directly.

The acetate sheets are so cheap that it doesn't matter if you destroy one when you remove it. If they are not too big, you can also print

You can see a picture of the sort of results I have managed to obtain at:

If there's any yellow in the original it might fade over a few years and look generally purple-ish due to the only fast colors, cyan and magenta. I'd look into that before trying anything based on ink jet printing. Silk screen it. Can't go wrong with that; well proven, time-tested old-style tech.

Most of mine are on die-cast boxes about 4" x 6". There is always a layer of double-sided tape showing at the cut edge, so it can be prised open at the corner with a knife or similar imstrument.

There is an adhesive called "Copydex" in the U.K., which is a latex emulsion that becomes rubbery when the water component evaporates. "Low tack" would be a polite way of describing it - the problem isan't removing it, but getting it to stay on in the first place. I have used it to stick paper copies of the artwork onto the front panel to use as a drilling jig, then it can be peeled off easily. The latex tended to wrap itself around the drill bit . . . followed by the paper label.

I have used PVA adhesive, with much greater success. It wouldn't be any use for permanent fixing on metal but the non-waterproof grade holds the label long enough to allow drilling and can easily be removed with water and a scouring pad.

That's a good idea if all your panels are the same size - no two of mine are ever alike.

My front panels get a bit of prodding and scuffing - but nothing too violent.

If you use White Spirit, the smell will be no worse than fresh paint and will clear quite quickly. There is also a form of refined petroleum ("White Gas") sold by Colemans for their camping stoves, that is more flammable but doesn't leave any lingering smells at all.

You might find the solvent attacks the print. Several thin layers, sprayed from a distance, are preferable to one thick layer sprayed closely.

And doesn't depend on the serviceman having the skill and experience to spot the cause that caused the cause of the fault.

After fixing the acetate sheet I burn them through with a soldering iron, then trim up the flash with a rat-tailed file (file towards the panel, never away from it). On that particular piece of equipment, I may have cut around the meter hole with a knife because it is rather large.

Our boards are blue solder mask and yellow ref designators. I'll leave one out on the deck, in the fog and rain and the (even-sometimes) sun.

It looks to me that some of our board houses are using inkjets for the silk layers. More on proto-sized runs.

That's the biggest one I have made, about the size of an A4 sheet of paper; I chose it because the picture of it it was the easiest to find. There's a rather poor picture of a smaller one at:

There are some very strong rubber cements with organic solvents, Copydex is a water-based emulsion and is very weak.

That's the sort of thing Copydex is used for, you can rub it off with finger pressure.

The area shouldn't matter, for every extra square foot of material there is an extra square foot of adhesive.

My sheets are 0.004" thick, a bit flimsy by your standards.

Either of those should work.

The holes produced that way tend to be jagged and the knife is soon blunted by cutting into the aluminium panel. A soldering iron gives a nice smooth finish but throws up a 'flash' of melted material which is easily trimmed off with a file. It is a quicker and more accurate process than trying to cut tiny circles with a knife. The knife is good for trimming excess tape off the outside edges.

It might work but with acetate sheet iit is more likely to melt it by friction, rather than cut it. Acetate is notorious for being difficult to cut without tearing, which is why disc recording blanks are always made of cellulose nitrate, despite erroneously being called "Acetates".

If you have pre-punched the sheet. alignment is simple: put pegs through the holes in the sheets and use them to align with those the panel. The 'alignment tool' could be a piece of wood with plastic-sleeved nails in strategic locations. Drop the adhesive-coated sheet over it, then offer it up to the panel.