Spray painting antenna

[MB]

I have a black Antennex VHF-Hi B1443 that is getting a little rusty. I was thinking about repainting it and was wondering which type of spray paint I can use.

Can I use Rustoleum?

I have heard that you are not suposed to use certain types of paint. Does anyone know what I should stay away from?

 

[ke5lvt]

use no paint with any metal content ie: metal flake

 

[MB]

use no paint with any metal content ie: metal flake

How do I tell if it has metal flakes in it? No where on the can of Rustoleum I have does it say anything about metal content.

 

[AK9R]

There should be a list of ingredients on the can. Look for metallic-sounding compound names, like iron oxide, titanium dioxide, zinc chromate, etc.

You also might want to try a hobby shop that handles model railroad supplies. They should have a metal blackener that causes a chemical reaction on the surface of the metal rather than covering it with a pigment like paint does. The chemical blackening might work better than paint in the long run.

For what it's worth, I have a Larsen NMO2/70B that is over 10 years old and still has the original coating on it. The top 6 inches looks pretty rough up close, but you can't tell from a distance and it sitll performs just fine. You take that to mean that either ugly doesn't matter or Larsen uses a better coating than Antenex.

Bob...

 

[Al42]

Antennas are normally plastic coated. Any plastic based paint, like Krylon, is good. But the rust has to be addressed, or it will just continue to rust under the paint. Use something like Naval Jelly to stop the rust, clean thoroughly, then paint.

Keep the paint away from any insulation on the antenna, like plastic separating the element(s) from the base. You can mask the insulation (liquid masking tape is great for irregular surfaces like that), paint away, then remove the masking when the paint has dried completely.

 

[MB]

I just don't understand the concept.

If the antenna is made out of metal, why would it matter if the paint that covers it has metal in it??

 

[John_M]

MB:

Higgler (Electrical)

Well,
As an antenna engineer with some great test equipment, if anyone wants to send me a painted and non painted antenna, a simple test takes just 10 minutes and it's easy to do, and I won't charge you anything (other than return shipping). You could also send me the paint for loss tests, that'll cost you a bit, I'd have to make a test setup special.

In general, low frequency wider bandwidth antennas can be painted with most non metallic paints and you'll never see the difference.

The worst antenna to paint is a narrow band antenna (GPS antenna is best example) using a thick paint coating. It'll shift the frequency downward and not work in your frequency band anymore.

Narrow bandwidth (typically thin antennas = narrow bandwidth) antennas, if designed properly should have a thick radome so that multiple thick paint coatings (or rain/ice) will be far enough away from the metal radiating part of the antenna to be out of the field.

On the same thought pattern, water is dielectric = 81, and very high loss, much much higher than 99.999% of all paints. That's the worst paint equivalent (other than metallic paint) that you can imagine. If it works in the rain, generally it'll work with a little extra paint on it.
kchiggins
Toyon Research Corporation
Antenna Group.

Metallic paint has a high dielectric constant (Basically, it provides a barrier between
the electromagnetic waves and your antenna). Painting an antenna protects the antenna from the elements and painting it is also for appearance. That is basically the reason to paint it.

 

[eyes00only]

John

I was just watching this post to learn something, and your expertise is greatly appreciated.

Jerry

 

[kb2vxa]

Hi John and all,

I was hoping someone would remember distributed capacitance and it's effect on resonance! Quite right, any insulating coating causes a downward shift in resonance so the conductor must be shortened accordingly. I wasn't going to get into such detail but what it amounts to is you can strip and repaint a painted antenna with a THIN coat of non-conductive paint but if it's bare metal LEAVE it that way, just remove the corrosion. BTW, painting an insulator won't hurt if it's non-conductive paint but it will make it difficult to disassemble. I remenber a neighbor who painted his windows shut, then came the summer heat. (;->)

"There is a fine line between hobby and mental illness."
How many here besides myself have crossed the line?
"Welcome to my nightmare."
Alice Cooper

 

[ind224]

Three years ago I got two Antenna Warehouse discones and had them sprayed with "Line-X" a "Rhino Lining" type material.
I was assured the stuff had no metal in it and although the applicators screwed me on the price (instead of doing it when they were doing another job like they said) they came out great.
Black and beautiful, @ 30' feeding my 2045 w/ LMR400 I get Indianapolis Ground 11 miles away, packet and voice from the Space Station on good passes, Bloomington Fire,Tipton County,Hamilton County, IN (EDACS) so from 120.9 to high 800mhz no problem with some as far as 60 miles.
I expect them to last "forever", even the crappy hubs.

I'll test the paint for metals...I'll do Krylon, Rustoleum and generic Wallmart stuff and report back.
Was your purpose stealth or protection?
Scan on.

 

[MB]

I'll test the paint for metals...I'll do Krylon, Rustoleum and generic Wallmart stuff and report back.
Was your purpose stealth or protection?
Scan on.

That would be great! The contents are not displayed on any spray paint can I have ever looked at. Also, no can I have ever looked at tells if hit as metal in it either.

I would like to use black Rustoleum enamal. That would be great if you could test this!

 

[Al42]

Most "enamel" paint has a fairly high dielectric constant, so keep the coating as thin as you can get it.

 

[dic]

I just bought a new Austin Spectra(?) wide band scanner antenna.
Some of the metal parts are unpainted brass and some are black. It is a good looking antenna.
I painted my previous antenna flat black (paint type unknown) and thought it looked much less obvious completely black.

So it IS okay to paint the antenna with a thin coat of non-metallic paint?
Or would it simply be better to leave it alone?

Dic
N1XBA

 

[kb2vxa]

Hi again,

I suppose you could test paint for electrical resistance with an ohm meter on a high scale, conversely if you have a conductance scale (seimens) you can test for conductivity. I would avoid a hipot or IR tester, shooting 500VDC through a flammable liquid could be just a mite hazardous.

One very good way of testing paint and plastic (some PVC is conductive) is put it in the microwave with a glass of water to absorb excess energy. If it gets warm it's conductive but just remember to paint a known non conductive object and let it dry first. You don't want to end up like the Mythbusters, remember the explosions?

If you have some metal flake paint around you can have your very own indoor fireworks display for the holiday, just a thought from a warped mind.

Edit;
"So it IS okay to paint the antenna with a thin coat of non-metallic paint?"
Dic, what did we say about isulating coatings detuning an antenna? Your answer to save you the trouble is leave it alone. BTW guys, don't mistake black anodized coating for paint, it's a permanent form of protection from weathering, don't mess with it.

 

[MB]

Most "enamel" paint has a fairly high dielectric constant, so keep the coating as thin as you can get it.

Al42, so what spray paint would you recommend?

 

[John_M]

MB: Plasti Kote is a good choice.

From what I have read it is people along the coast that experience the most corrosion on antennas due to salty misty air.

 

[kb2vxa]

Tell me about it John! (;->)

 

[b7spectra]

I've got 2 1/4 wave NMO antennas on the top of my black truck. I really cheated and took a Sharpie marker to them and turned them black! Yeah, I have to "re-mark" them every few months, but it's real cheap to do it!

 

[n7jei]

I love the "sharpie" comment! Glad to see someone else does that on their black mobile antennas.

 

[trooperdude]

Liquid Gun Blueing