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From: liz@poppyrecords.invalid.invalid (Liz Tuddenham)
Newsgroups: sci.electronics.design
Subject: Re: poor man's decal
Date: Thu, 3 Apr 2025 09:11:41 +0100
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Don Y <blockedofcourse@foo.invalid> wrote:

> On 4/2/2025 10:23 AM, Liz Tuddenham wrote:
> > Don Y <blockedofcourse@foo.invalid> wrote:
> > 
> >> On 4/2/2025 7:57 AM, Liz Tuddenham wrote:
> > [...]
> >>> Usually the entire surface and a bit beyond, then trim off the excess.
> >>
> >> Doesn't that make it hard to remove?  Or, are yours "small(er)"?
> >> (Note my smallest is 8x17 and they quickly get larger)
> > 
> > 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.
> 
> Hmmmm... the exemplar you provided seemed to be larger than that (?)

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:
<http://www.poppyrecords.co.uk/other/Microphones/StereoCrossedRibbons/In
structions.pdf>


> >> I was
> >> assuming I would need a low tack adhesive -- almost like Post-It
> >> notes...
> > 
> > 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.
> 
> Yes, we have similar adhesives ("rubber cement", etc.).

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

[...]
> But, some applications deliberately want low tack (e.g., in masking
> artwork)

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

[...]
> I used a spray adhesive to repair a headliner.  Granted, it's not
> a heavy weight to support.  *But*, it is "upside down" perpetually
> (so, gravity is trying to pull it off) and very large (a dozen square
> feet?).

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

[...]
> I opted for the 7 mil variety of laminating film as it adds a bit
> more armor (3 mil is just cosmetic; 5 mil is probably marginal;
> 10 mil is probably overkill)

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

[...] 
>(I have nothing
> stronger than xylene and MEK on hand 

Either of those should work.

[...]
> > 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.
> 
> A *pointed* Xacto knife isn't suitable for the whole task?  Or, do you risk
> the cut "tearing"/"running" through the acetate to areas undesired?

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.


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