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From: liz@poppyrecords.invalid.invalid (Liz Tuddenham)
Newsgroups: sci.electronics.design
Subject: Re: poor man's decal
Date: Wed, 2 Apr 2025 15:57:39 +0100
Organization: Poppy Records
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Don Y <blockedofcourse@foo.invalid> wrote:

> On 4/2/2025 4:23 AM, Liz Tuddenham wrote:
> > Don Y <blockedofcourse@foo.invalid> wrote:
> > 
> >> I need a full-color, durable decal to label a front panel.
> >> The panel is ~8x17".  I'm only looking for prototype quantities
> >> (someone else can deal with production quantities and "revised
> >> artwork").
> >>
> >> I think I can just color print the image, 1:1, laminate it
> >> and use a spray adhesive to affix it to the actual panel.
> > 
> > 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.
> 
> Do you cover the entire surface with tape?  Or, just the edges?

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


> Most of the double-sided tape I've used would have too much tack
> if used to completely cover it; removing the decal would be tedious.

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.


> [I just want the decal to stick to the surface, now cling for dear life!]

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:

1) Put the tape on the panel, then use a soldering iron and/or file to
clear the tape from the holes where the control shafts and switches will
be.  By shining a light through the holes I can then line-up some +
marks on the print, which correspond to the hole centres, while I bring
the decal onto the sticky surface in exactly the right place.

2)  Put the tape on the panel etc as before. then line up one long edge
of the decal on the edge of the panel and let it touch.  The decal can
then be swung down, using that edge as a hinge, and carefull pressed
onto the panel starting from the hinge edge.  

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

> 
> > The unprinted acetate surface is fairly durable and the print side is
> > towards the panel, so it can't be scuffed off.
> 
> Yes, I took that approach with a digitizer overlay.  But, that's a pretty
> gentle environment; you're never poking at it with anything that may
> have an edge.

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).


> > If you need to change it, the sticky residue from the tape can be
> > removed with white spirit or petrol.
> 
> I was hoping to eliminate the use of solvents.
> 
> Many products, here, bear "printed labels".  Historically, these have
> been paper; removing them is a chore as the label needs to absorb a
> solvent to facilitate its removal (I use water, alcohol, mineral
> spirits and, rarely, acetone -- as it often attacks the surface to
> which the label is adhered).

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

> 
> But, there are also similar labels printed on a plastic/nylon
> sheet.  These can be removed "intact" -- with patience -- just
> by getting a corner "started".  The adhesive used is weak enough
> (and the label material strong enough) that it doesn't tear the
> label as it is removed.  And, the printed content is well-bonded
> to the substrate such that it doesn't require any additional
> coating (or, that coating is applied in the process of making
> the label).
> 
> So, I'll either print on paper and use a laminating *pouch* (so
> both sides of the paper are coated in plastic instead of having
> paper on one side) OR try mylar (or acetate) and hope the printed
> material doesn't "linger" after the adhesive is released.

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
3-up or 4-up on an A4 sheet, so you can easily keep a few spares.


> As I said in my post, it's just to get through prototypes so it
> looks "professional" to VCs and is as *functional* as the real
> decal would be ("How do you service this?  It seems awfully
> costly to adopt a replace-as-FRU policy")

You can see a picture of the sort of results I have managed to obtain
at:
http://www.poppyrecords.co.uk/other/DistortionMeter/Manual.pdf


-- 
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk