J-B Weld and galvanic corrosion?

[ts]

Wasn't sure if this should go in "rebuilds", but thought I'd try here first (please move this thread if it's a better fit elsewhere).

Anyone know if I should worry about the iron/steel in J-B Weld causing galvanic corrosion on my Starcraft when used for filling holes in hull (transom, decking, etc.)?

Thanks!

 

[bananaboater]

Re: J-B Weld and galvanic corrosion?

Good question. Hope not. Many of us use it. I went through a couple tubes on mine.

Any chemists/electrologists out there?

 

[Bob_VT]

Re: J-B Weld and galvanic corrosion?

It is mixed with so much epoxy it will not hurt anything. I feel safer using pc 11 which does not contain metal anyway.

 

[ts]

Re: J-B Weld and galvanic corrosion?

Do you think 5200 would work for filling screw holes in the deck instead of JB-Weld, or would it be brittle?

...or maybe just PC 11. Do you buy it online, or?

 

[Outsider]

Re: J-B Weld and galvanic corrosion?

5200 is first an adhesive, second a sealant. If you're filling holes, use a filler like Marine-Tex ...

 

[ts]

Re: J-B Weld and galvanic corrosion?

True...:redface:

What's a good backer when using JB or Marine-Tex to fill holes?

Maybe a block of wood taped under the deck temporarily? Just tape?

 

[ezmobee]

Re: J-B Weld and galvanic corrosion?

I used some little squares of aluminum flashing.

 

[ts]

Re: J-B Weld and galvanic corrosion?

Oh, good call.

Makes me think of those body work kits you can buy that come with bondo and a piece of aluminum with sticky stuff on one side. I think I'll see if I can find some of that - minus the bondo.

 

[sprintst]

Re: J-B Weld and galvanic corrosion?

I was thinking the same so I used that Starbrite epoxy aluminum putty. http://www.starbrite.com/productdetail.cfm?ID=1461&ProductCat=Marine&ProductSCat=Epoxies%20%26%20Adhesives%20%26%20Caulks&ProductSSCat=Epoxies

Whether it will pop out ad I will sink remains to be seen The Marinetex looks cool as it is sandable but have never tried it.

I had some of this stuff sticking out the backside of the transom skin and hit it with a wire wheel to grind it down and the patch held.

 

[ezmobee]

Re: J-B Weld and galvanic corrosion?

On my Jupiter, I filled some holes in the transom with JB. However I filled them with the transom wood already in place. So there wasn't really any JB on the inside of the transom skin. I sanded them flush and they held but after a few months you could see under the paint that they had "popped". I'm thinking with some JB on the inside as well and the flashing backer, I should be good this time.

 

[prelude219]

Re: J-B Weld and galvanic corrosion?

i did the same on the transom and i found one that "popped" also this spring. I filled a hole in the bilge then gluvit'ed it and its still water tight. I'm wondering if i didn't apply it right to the transom hole. But everywhere else worked great for me

 

[ts]

Re: J-B Weld and galvanic corrosion?

You guys think maybe it was from the transom flexing just enough to pop the JB?

 

[ezmobee]

Re: J-B Weld and galvanic corrosion?

Maybe, but I think the real issue was all it had to "grab" was the edges of the hole and that wasn't enough.