# Does Thompson's Water Seal contain chem. harmful to Alum. ??



## G Lap (Nov 12, 2011)

Does Thompson's Water Seal contain any chemicals that are harmful to bare aluminum? Is this a safe product to use for sealing wood that is in my jon boat, and in direct contact with the aluminum? Thanks for the input.


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## JeffChastain (Nov 12, 2011)

Good question. I used thompson's on my benches. Hope it's alright!


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## shawnfish (Nov 12, 2011)

i beleive it will not do any harm, but im the village idiot..... :lol:


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## jigngrub (Nov 12, 2011)

Thompsons is little more than parrafin (wax) and mineral spirits, I don't think either will harm aluminum.


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## Captain Ahab (Nov 12, 2011)

jigngrub said:


> Thompsons is little more than parrafin (wax) and mineral spirits, I don't think either will harm aluminum.



X2


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## shawnfish (Nov 12, 2011)

just read the side of a can of it and couldnt find anything that would suggest harm.


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## Jay415 (Nov 12, 2011)

I've heard of a lot of people using it and haven't heard of any issues.


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## shawnfish (Nov 13, 2011)

after tearing my floors and decks out the other day i didnt notice it but today i noticed some off color white spots on the aluminum benches my deck was attached to and i did use thompsons to treat the deck. i ran my hand across it and the white areas felt like a real fine grit sandpaper???? as soon as i figure out how to make the file size on pics i took fit to post them i will. very odd as i cant figure out what else would have caused it.


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## Jay415 (Nov 13, 2011)

shawnfish said:


> after tearing my floors and decks out the other day i didnt notice it but today i noticed some off color white spots on the aluminum benches my deck was attached to and i did use thompsons to treat the deck. i ran my hand across it and the white areas felt like a real fine grit sandpaper???? as soon as i figure out how to make the file size on pics i took fit to post them i will. very odd as i cant figure out what else would have caused it.


ever use the boat in salt or brackish water? Sounds like it could be salt corrosion.


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## G Lap (Nov 13, 2011)

I was thinking the same thing . . . about possibly being caused by salt corrosion. My last jon boat had some corrosion which I believed was caused by saltwater. The previous owner had fished often in saltwater. 

This corrosion was in tight areas where the seawater would have been trapped (like between the bottom of transom brace and the bottom of boat). This area would have dried from the seawater after each fishing trip, but deposits of salt could have been left as the solution evaporated. So, over time salt can build up in tight areas such as this. Even rinsing the boat with freshwater would have a hard time at removing salt from very tight areas such as this. 

This type of corrosion that I saw was eating little holes in the aluminum. I believe that this same affect could be seen on bunk boards that are covered in carpet. After fishing in saltwater and loading the boat, the bunk carpet would be wet . . . the water will evaporate, leaving the salt behind. Over time, the concentration of salt in the carpet could possibly increase.


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## G Lap (Nov 13, 2011)

I sent a question to Thompson's, asking if their product was corrosive to aluminum . . . here is the response that I got.

*Thank you for contacting Thompson's. We appreciate your inquiry.

Our products are not considered to be corrosive, however we do not test for application on metal surfaces. If the Aluminum has been painted or the finish oxidized it will be very difficult to remove any over-spray without effecting the aluminum. Our products are not really designed for marine type of applications. While the product will not necessarily be submerged, it will be subjected to a higher amount of moisture. I would recommend checking with your local boating and marine store for a finish they would recommend. Our Parent company, Sherwin-Williams manufactures a variety of coatings, including marine grade finishes that would meet your needs. You may want to contact them for a product.

I hope this information is helpful. Please let me know if you have any other questions.*

Thought some of you would be interested in reading it . . .


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## shawnfish (Nov 13, 2011)

Jay415 said:


> shawnfish said:
> 
> 
> > after tearing my floors and decks out the other day i didnt notice it but today i noticed some off color white spots on the aluminum benches my deck was attached to and i did use thompsons to treat the deck. i ran my hand across it and the white areas felt like a real fine grit sandpaper???? as soon as i figure out how to make the file size on pics i took fit to post them i will. very odd as i cant figure out what else would have caused it.
> ...



thats kinda what it looks like, but no its never seen saltwater or brackish water. im in omaha...


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## shawnfish (Nov 13, 2011)

here's what i found, and it was only where the thompsons treated plywood was.


like i said, it felt like fine grit sandpaper and cleaned up with some steel wool but i had to really put some elbow grease into it...


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## G Lap (Nov 13, 2011)

Shawnfish,

Did it look like it caused any damage or penetration into the metal, or was it just the paint? 

Could that possibly have been caused by the plywood rubbing there when someone was on the deck?

Since you were treating the wood with Thompson's, I would assume that the wood was not pressure treated?

How long did you have the wood mounted there on your bench seat?


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## shawnfish (Nov 13, 2011)

G Lap said:


> Shawnfish,
> 
> Did it look like it caused any damage or penetration into the metal, or was it just the paint?
> 
> ...



no damage or penetration into the aluminum bench, not sure what you mean by "was it just the paint" the bench is bare aluminum. and it wasnt from rubbing, i had the deck carpeted on both sides and it was secured good and didnt shift at all. and your assumption is correct, it was not treated. funny thing is my floor supports were treated and the floor wedged between the front and back bench and was not secured any way besides that. so i figured id keep them in till now because i could just lift it up to check for any signs of a chemical reaction from the treated supports and there was no sign of anything at all where they rested on the floor, only there where the thompsons treated deck sat??? weird but i dont know what else would have caused it.

oh, i replaced the 3/4 treated deck with the 1/2 inch thompsons treated deck in may if im not mistaken. either way it was no longer than 6 months.

one more thing, i put 5 coats of thompsons on a small peice of pine ply and screwed it to a small sheet of aluminum. im gonna check it every few weeks or so to see what happens so i know for my own satisfaction if it was the thompsons or not.


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## Jay415 (Nov 14, 2011)

shawnfish said:


> ...i had the deck carpeted on both sides.....


then the Thompson's never touch the Aluminum if the carpet was on the bottom too. Still looks like salt corrosion to me. What about road salt from snow storms?

Could also be battery acid corrosion..ever have any battery leaks? 

My guess is since you had carpet on the bottom too is that some chemical soaked into the carpet and cause the corrosion. Not the Thompson's. Just an assumption, I could be wrong.


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## shawnfish (Nov 14, 2011)

Jay415 said:


> shawnfish said:
> 
> 
> > ...i had the deck carpeted on both sides.....
> ...




i should have explained a little better when i said both sides were carpeted, when i carpeted the deck i left about six inches overhang around the perimiter and folded it around the edges to the underside of the deck and then used leftover peices to fill the bare spots, so there were some, but small spots of exposed plywood. my boat has never seen snow as its covered every winter and in my garage and my grandpa did the same thing when it was his(he bought it new in 1979). im positive nothing else came in contact with the carpet that would have soaked through to cause it. and there has never been a battery anywhere near the bow until this year and it's a sealed gel type so i know thats not the cause, plus it was mounted under the deck on the floor of the bow. im convinced it was the thompsons, and time will tell as i observe my thompsons experiment over the next several months.
but we'll have to wait and see, but i could be wrong also.......


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## Jay415 (Nov 14, 2011)

Hmmm just throwin out ideas. Still it doesn't sound like the Thompson's though. You said you used scrap carpet to fill the gaps. The gaps needed to be filled cause the plywood wasn't making contact with the aluminum because of your 6" overlap. I'm at a loss for ideas right now. 
I guess you just have to think back about what the boat has been through. Maybe like the one time something may have been spilled.


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## Jay415 (Nov 14, 2011)

I was just looking at the pics again and they look patchy. Kind of like how you explained filling the gaps with carpet. Is it possible that it is rubbing wear? Is it where the carpet patches were? Like the edge seems to have more. I'm thinking maybe because that's where you had you 6" overlap.


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## shawnfish (Nov 14, 2011)

the plywwod had good contact, i just wanted the carpet as a buffer between the two so there was no void. and like i said before it was not caused by rubbing, the deck was locked down 100% tight and a earthquake would not have made it shift in any way. it wasnt from the patches or overlap as it was on the whole bench(i cleaned most of it up before the pics). and the scraps were the same carpet so i know that nothing got on it before i put them on. and i know for a fact that nothing ever spilled besides maybe a pop or a beer, but i dont remember that happening this summer.

im getting some comfort knowing it puzzles you as much as me, at least im not the only one scratching my head. lol!


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## Jay415 (Nov 14, 2011)

If you were filling voids with carpet wood and aluminum were not touching...the carpet was separating them. And I don't know about beer but soda pop can be very acidic.

Movement is still a possibility. I know it does appear to move during use, but wood and metal expand and contract at different rates with temperature. That little movement can cause rubbing. It doesn't take much. Ever see nails popping out of a wood deck? Trust me they move.


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## G Lap (Nov 14, 2011)

The reason I was curious about using Thompson's is as follows. I had just bought a new welded jon boat. The wood in the transom is covered with aluminum, but there are openings along each side of the wood where you can feel the wood in there. I just thought I might put some Thompson's on the wood there to help keep moisture from penetrating into this porous endgrain of the wood, as I know the wood is not treated or anything. Even if it is not exposed to direct rain, there is a lot of moisture in the air sometimes and I'm sure the wood would absorb this. Maybe I am looking into this too far, just thought it might be an easy way to help extend the life of the wood.


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## shawnfish (Nov 14, 2011)

G Lap said:


> The reason I was curious about using Thompson's is as follows. I had just bought a new welded jon boat. The wood in the transom is covered with aluminum, but there are openings along each side of the wood where you can feel the wood in there. I just thought I might put some Thompson's on the wood there to help keep moisture from penetrating into this porous endgrain of the wood, as I know the wood is not treated or anything. Even if it is not exposed to direct rain, there is a lot of moisture in the air sometimes and I'm sure the wood would absorb this. Maybe I am looking into this too far, just thought it might be an easy way to help extend the life of the wood.



maybe try some foam or silicone? just a thought. a pic would help.


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## shawnfish (Nov 14, 2011)

Jay415 said:


> If you were filling voids with carpet wood and aluminum were not touching...the carpet was separating them. And I don't know about beer but soda pop can be very acidic.
> 
> Movement is still a possibility. I know it does appear to move during use, but wood and metal expand and contract at different rates with temperature. That little movement can cause rubbing. It doesn't take much. Ever see nails popping out of a wood deck? Trust me they move.



i have no doubt about nails popping up during different temps, and beleive me, i had that deck bolted down tighter than snot. and also it was only on there during the summer so temp fluctuations were very minimal and also there were no "white marks" on the little bench in the bow. i think the front bench was not affected because it sits about a inch and a half below level with the bench with the marks so i used a peice of solid plastic block on top of the alum. square tubing that supported the deck in the middle to level it. and not that im arguing with you but even it were caused by rubbing for that amount"marking" i beleive it would have taken a lot longer than 5 or so months to occur. i also did a lil research on the acidity of soda pop having any affect on aluminum, and plus it would have had to soak from the top then around the edge and back between the wood and aluminum through the carpet and that doesent sound very likely to me. and i cant remember spilling anything also....any more ideas would be nice cuz im out of them and still think it had to be the thompsons.( i cant wait for 5 months to go by to take my experiment apart and see the results) by).....


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## Jay415 (Nov 14, 2011)

shawnfish said:


> ...any more ideas would be nice cuz im out of them...


well I'm all out right now. Let's see how the experiment turns out :lol:


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## shawnfish (Nov 14, 2011)

will do..... :lol:


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