Nitrocellulose over shielding paint

[jammybstard]

I've developed a love hate relationship with shielding paint over the last few days
It's really helped with the noise but it's messy stuff when you're fitting the electronics it rubs off on everything.

So on my new build, I'm planning a Strat' body with a rear cavity so I can experiment with building some on-board effects, the body will come from Guitarbuild.com unpainted so I will be applying Nitro' and I will also want to shield it.

I know about Foil tape but, I was wondering if I could apply the coats of Shielding paint to the cavities before I start the cellulose sealer/primer application to the body, that way the primer/paint/Lacquer will would seal over the shielding paint too and hopefully keep everything nice and clean.

Obviously I would do a test before I started, but has anyone ever tried that before?

 

[schmee]

If the shielding is quite dry the lacquer will likely dry fast enough to not effect it. However, watch out that you can ground the shielding paint to the electronics with nitro over..... maybe that will inhibit grounding? Nitro is good wood sealer, so maybe do the nitro first then the shielding?

 

[KokoTele]

You'd have to scrape some lacquer off of the shielding paint to expose some of the shield to ground to, and that in itself can create some issues. They're probably small issues, but I can't think of any good reason to lacquer over the shielding paint.

I've never experienced shielding paint rubbing off when it's dry, though. What paint are you using? Are you sure that you've stirred it enough? Maybe it's just too old?

 

[jammybstard]

I used the G-Shield electro smog shielding paint from Northwest Guitars:
GShield
If you rub it when it's dry it's like soft pencil lead.
Pretty sure I stirred it ok.

Grounding won't be an issue, I'll just put grounding point in before the nitro and then tape of the grounding point and spray over the top.

 

[Boreas]

Finish first, shield last is my motto. But then, I prefer copper tape. I love the way it slices through my fingers if I am not paying attention.

 

[KokoTele]

I used the G-Shield electro smog shielding paint from Northwest Guitars:
GShield
If you rub it when it's dry it's like soft pencil lead.
Pretty sure I stirred it ok.

Grounding won't be an issue, I'll just put grounding point in before the nitro and then tape of the grounding point and spray over the top.

Ahh... it seems that their product is a bit of a special unicorn. They specify that it can be coated over with emulsion paints, and those are typically other waterborne paints. You should write to them and ask about lacquer compatibility. My guess is that it shouldn't be an issue as long as the shielding paint is fully dried, but that's just a guess.

 

[Peegoo]

@jammybstard

Yep, it works great. This is how I do it when a client requests shielding paint.

-Apply at least two coats of shielding paint in the cavities and channels with a small brush
-Solder an 8" long hookup wire to a small ring terminal
-Use a short wood screw to attach the ring terminal in a corner of the main control cavity
-Test across all cavities to ensure there's some continuity throughout
-Shoot your nitro

The wire on the ring terminal serves as your connection to cavity shield.

 

[jvin248]

... I prefer copper tape. I love the way it slices through my fingers if I am not paying attention.

Lol that's the problem with copper, and if you buy "a kit" there is almost enough to do the job but not quite.

I hate the paint.

I just use aluminum flashing tape, the stuff that sticks on hot and cold furnace ducts for thirty years. A roll for eight dollars shields two dozen guitars. Use a Meter to verify continuity to everything.

If you are taming a Strat or any with a jack 'remote' from the main shielded cavity, make sure to use shielded cable to the jack. I've seen the typical wire pair collect half the idle noise floor.

.

 

[Boreas]

Lol that's the problem with copper, and if you buy "a kit" there is almost enough to do the job but not quite.

I hate the paint.

I just use aluminum flashing tape, the stuff that sticks on hot and cold furnace ducts for thirty years. A roll for eight dollars shields two dozen guitars. Use a Meter to verify continuity to everything.

If you are taming a Strat or any with a jack 'remote' from the main shielded cavity, make sure to use shielded cable to the jack. I've seen the typical wire pair collect half the idle noise floor.

.

I buy a big roll as well, but it obviously costs more than aluminum. But I suspect I could still cut myself with it.

 

[old wrench]

Lol that's the problem with copper, and if you buy "a kit" there is almost enough to do the job but not quite.

I hate the paint.

I just use aluminum flashing tape, the stuff that sticks on hot and cold furnace ducts for thirty years. A roll for eight dollars shields two dozen guitars. Use a Meter to verify continuity to everything.

If you are taming a Strat or any with a jack 'remote' from the main shielded cavity, make sure to use shielded cable to the jack. I've seen the typical wire pair collect half the idle noise floor.

.

Good point about using shielded cable for the run to the output jack !!!

Folks tend to overlook shielding this wiring run because in some cases it's a relatively short run, but that short run has the potential to develop some considerable noise if it's left unshielded.

Trying to shield that wire pathway on a Strat or Tele with shielding tape is a real pain - use shielded cable instead



If you find yourself needing a short piece of shielded cable for this job or another - you can go to your local box store and buy a foot or two (or more) of the shielded communication cable that they sell by the foot - get the stuff with two stranded conductors and a ground wire - the two conductors are 22awg

"They" (I've bought it at Home Depot) also carry the same type of shielded comm cable with four 22awg stranded conductors plus a separate ground wire.

The box store is a handy source for shielded cable - especially if you just need a short length


.

 

[Peegoo]

If you're shielding with copper tape, you can use the same tape and wrap it over a wire run that goes through an area that's unshielded. Be sure to ground at least one end of the shield.

When shielding, it's good practice to have only a single connection to circuit ground at one end of the wire shield--not both ends. In a passive guitar circuit this single connection is not so critical because there's no opportunity for a ground loop occurring; all components are at the same ground potential.

 

[Reedo]

Not a paint fan here, I always use copper slug tape, but ymmv.

 

[jammybstard]

@jammybstard

Yep, it works great. This is how I do it when a client requests shielding paint.

-Apply at least two coats of shielding paint in the cavities and channels with a small brush
-Solder an 8" long hookup wire to a small ring terminal
-Use a short wood screw to attach the ring terminal in a corner of the main control cavity
-Test across all cavities to ensure there's some continuity throughout
-Shoot your nitro

The wire on the ring terminal serves as your connection to cavity shield.

Ah that's cool to hear, it would have been suspect to think i might have had an original idea
Do you use the water based G-shield stuff I have by any chance?

 

[Peegoo]

Ah that's cool to hear, it would have been suspect to think i might have had an original idea
Do you use the water based G-shield stuff I have by any chance?

I have used the water-based shielding paint from StooMac and it worked fine. It's messy, so mask off everything you don't want the stuff to get on. When you attack your ground wire to it with a screw, paint over the screw with one or two coats of the stuff and allow it to dry. Then you can shoot your nitro over it and it will work great.

Ibanez was doing it this way in the 80s and 90s on their high-end stuff.

 

[archetype]

Finish first, shield last is my motto. But then, I prefer copper tape. I love the way it slices through my fingers if I am not paying attention.

In my experience, it's like a roll of razor blade.

 

[Ed Storer]

If you're concerned with chemical compatibility between the two coatings or bleed-through, then a shellac-based product like KILZ is a good barrier coat.

 

[J. Bonkosky]

I have used the MG Chemicals 841wb a few times now. It has never rubbed off onto anything once dry. Sounds like you may be using an inferior product.

 

[hopdybob]

one advise, do a test run on a piece of scrap wood.
why? you can test if the interaction of the 2 solvents is okay.

 

[jammybstard]

I have used the MG Chemicals 841wb a few times now. It has never rubbed off onto anything once dry. Sounds like you may be using an inferior product.

It's messy stuff for sure. But the shielding effect it's had on the Tele is I have to say excellent. It was nearly unusable with some gain stages on the board.
When I start the strat build I'll be making sure it's not an afterthought.

 

[jammybstard]

ye

one advise, do a test run on a piece of scrap wood.
why? you can test if the interaction of the 2 solvents is okay.

Yes, good advice .
I haven't received the nitro yet, bit I did a quick test with polyurethane and that certainly seems to seal it over without any issue.
I report back when I've tested it with the nitro.