Great foil for pickguards, etc., but not much else

[Steve A.]

I picked this up at Food Maxx "Extra strength Heavy Duty Aluminium Foil" from handi-foil. 100 sq ft.

It is certainly very heavy duty but it does not fold AT ALL! Crappy for cooking but perfect for shielding pickguards or control compartment covers. Now to get me a can of 3M #357 spray adhesive as rubber cement would not do it justice!

UPC 0 52092 82200 1



Steve Ahola

[Jason Rodgers]

Woa, diamond plate foil! I use aluminum foil tape that you can pick up at the hardware store. Any foil tape is challenging to cut, peal, and place, but I hate spray adhesive in all sorts of ways.

[rjb]

I use aluminum foil tape that you can pick up at the hardware store.

OK, if it's wide enough to do the job without seams.
I've never had luck maintaining long-term continuity across aluminum tape seams.
Tabs, schmabs, within a day oxide layer raises resistance to "not connected".
YMMV.

[Steve A.]

The foil itself is not diamond plate- it is very smooth and does not crinkle up. When I worked at an HVAC company the installers used 357 extensively to secure fiberglass insulation, etc. Spray it outside not around guitars or electronics.

[Fluoroscope 5000]

OK, if it's wide enough to do the job without seams.
I've never had luck maintaining long-term continuity across aluminum tape seams.
Tabs, schmabs, within a day oxide layer raises resistance to "not connected".
YMMV.

AFAIK, the tape side is not conductive. Are you saying the shiny side oxidizes to become non-conductive? My Aluminum tape is perfectly conductive and has been sitting out for years. You need to connect pieces with wire or some other method. You can also use it to soften the upper-mid response of your pickups with 0.015~0.03" layers under the pickguard around the pickups.

[rjb]

Are you saying the shiny side oxidizes to become non-conductive?

Yup.

My Aluminum tape is perfectly conductive and has been sitting out for years.

Mine too. As long as you use one contiguous strip of tape, everything is hunky dory.
Two strips with overlapping shiny side to shiny side - not hunky dory.

You need to connect pieces with wire or some other method.

There's the rub. How do you connect the pieces with wire? What other method?
I don't know how to solder wire directly to aluminum.
I've tried various methods of holding the tape face-to-face, but none have worked long term.

I've read somewhere on the web that you can tack-solder copper wire to aluminum by first rubbing the aluminum with a vinyl eraser dipped in copper sulfate. Haven't tried that yet.

[Fluoroscope 5000]

I'm not a guitar tech, but you only “need” to put tape on the bottom of the pickup cavities, and it doesn't need to be grounded. Shielding the pickup cavities doesn't really do much anyway, but a strip of tape on the bottom is easy, and it reduces hum-buzz from bad rheostats in vicinity. Neither does it need to be grounded around the pickups, but the static sink advantage if grounded is helpful.

Let me just get this clear. Can't you tape the control cavity with overlapping pieces, and connect it all with a few pieces on the bottom of a pickguard? The controls would then ground to the tape. I had no noise problems on a guitar I did that to. It was very quiet, but the pickups are very low hum, and I'm in an electrically quiet environment.

[big_teee]

GL,
T

[rjb]

Let me just get this clear. Can't you tape the control cavity with overlapping pieces, and connect it all with a few pieces on the bottom of a pickguard?

Sure, you can do that.
But if you open up the guitar and check the continuity between overlapping pieces, don't be surprised if the reading is way over a few ohms. Like, they're not actually connected.
On the other hand, if you don't have a problem don't fix what ain't broke.

[big_teee]

GL,
T

[rjb]

That "hybrid" approach sounds like a good way to go.
Do you run a wire between the cavity and pickguard?
I've seen that done in a Fender with conductive-painted cavity and foil-faced pickguard.

[big_teee]

Use shielding.
T

[Fluoroscope 5000]

GFS sells Strat Aluminum pickguard shields cheap. I've used a few for convenience and slight upper-mid softening.

big_teee, it is my understanding that Al does not block RF – only hum-buzz from faulty (unshielded?) rheostats. It may help around florescent lights (qualifies as EMI?), but I think it would have to be pretty thick to be significant. A ~1/16” thick Al pie tin will reduce SC hum just a bit when placed underneath. Even a reduction of a few dB can seem significant if the noise drops below annoyance level.

I thought Cu was required for RF protection, though. I think I once read that carbon paint doesn't really help with RF, but you really wouldn't know either way unless it was a problem. I don't have audible RF in my home environment. Although very low in level with certain SC pickups, the hum overshadows whatever else might be happening. Even my A/I preamp noise at about -100dB becomes an issue before any RF, but I'm curious to test the RF shielding of my guitars. I do hear my cordless mouse through my pickups if I get close to it – qualify as EMI?

I wouldn't think continuity would matter between overlapping Al tape pieces in the control cavity if they are all connected via an Al pickguard shield, no? Am I wrong to assume the Al shield would then ground the pots/switches, and I only need the ground wire from the bridge to the volume pot to the jack? I prefer not to do more soldering than needed, but grounding the pots/switches with wire wouldn't hurt. I don't think ground loops can occur within a passive guitar circuit.

On my latest Strat-type build (with an interesting wiring scheme I'll post a video demo of soon), the control cavity is conductive paint. I didn't add shielding in there, but did use a GFS Al shield and Al tape under the pickups. I did ground all the hardware with wire before realizing I may not have needed to. I left the switch ungrounded, and it's all fine.

Kinda surprised it came out right first try. I realize I should have checked continuity on all the wire before soldering – that could have been a nightmare. It took me over 5 hours to wire. It was my first really complicated project with ~25 wires & 3 caps. I spent many hours designing it, and I'm still going to do some cap tweaking to focus a few peaks to just what I want. I'm very happy with it, though. The Xover/HOoP blend feature ended up doing just what I had hoped. Sorry to go on about it. I'm just really jazzed.

[big_teee]

Excuse me, I was just trying to help.
I'm gone!

[rjb]

I wouldn't think continuity would matter between overlapping Al tape pieces in the control cavity if they are all connected via an Al pickguard shield, no? Am I wrong to assume the Al shield would then ground the pots/switches, and I only need the ground wire from the bridge to the volume pot to the jack? I prefer not to do more soldering than needed, but grounding the pots/switches with wire wouldn't hurt.

I don't pretend to be an expert, and wouldn't tell you not to do anything.

But I personally wouldn't trust the mounting to an aluminum pickguard shield to provide a dependable component ground- if only because mounting nuts can loosen.

My personal experience with overlapping Al tape pieces in a control cavity is that if you measure the continuity an hour after installation, the pieces are no longer "connected" to each other.

The problem is that aluminum very quickly forms a thin insulating oxide "skin". When you measure one piece of tape, your probes puncture the skin and you get a reading across the Al beneath the surface. When you have "skin to skin contact" between two layers, you get an unacceptably high resistance across the boundary.

Now, there are anti-oxidant compounds with names like No-Alox and Ox-Gard that improve the conductivity of aluminum electrical connections. They require that the surfaces be thoroughly cleaned before/during application, and that you have a good, tight, solid mechanical connection.
Ideal Noalox 0.5 oz. Anti-Oxidant Joint Compound-30-024 - The Home Depot
Anti-Oxidant Compound

So, grounding components via the shield might work- if you properly clean all surfaces and use anti-oxidant compound. And you might get continuity between the cavity and the faceplate (without running a wire between them) if you use compound.

But with overlapping strips of aluminum tape in a cavity or on a faceplate, you'd have to make a solid mechanical connection between the strips (maybe with staples or brads or screws?). Which, I think, would be ugly and more trouble than it's worth.

ymmv,
-rb