Is Thompsons water seal safe to put on plywood bottom of SFG?

cindgborgg 1/30/2014, 9:11 pm

I am new to SFG and excited to get started. My husband is in the process of building it. He decided to put Thompsons water seal on the plywood he does not think it is toxic or will leach into the soil. I beg to differ but am not sure. Does anybody know?

Goosegirl 1/30/2014, 11:20 pm

The main ingredient listed on its MSDS is Mineral Spirits - a toxin to the lungs and nervous system in its full strength, but in the amount in Thompson's it may not be an issue.

MSDS on pure mineral spirits says: "Products of Biodegradation:
Possibly hazardous short term degradation products are not likely. However, long term degradation products may arise."

But again, that is for 100% mineral spirits by weight, and Thompson's is 6% by weight. Yours to decide.

GG

meatburner 1/30/2014, 11:29 pm

If you are worried, call them and have them give you the information. That would be better than asking here. Just my opinion.

cindgborgg 1/30/2014, 11:32 pm

Thank you for your response. I really do not like the idea but since my husband already put it on and does not want to redo. Short term seems o.k. I guess for now.

Thank you,

Cindy

meatburner 1/30/2014, 11:47 pm

Cindy, I have no issue with what you are doing. I think you are just fine.

Rahab222 1/31/2014, 12:06 am

Mel recommends Linseed Oil to treat your boards with. However, it's sticky. I did A LOT of research on this, in order to treat the boards on my raised bed garden lumber and the only suitable product I found was PURE Tung oil. You can buy this at a paint store or they can order it for you. I think I paid around $30 for a quart in Houston. Linseed oil was cheaper and I found it at WalMart. I decided not to use the Linseed Oil because I didn't want everything blowing in the wind to stick to it during our LONG, HOT summers.

**sanderson** 1/31/2014, 12:10 am

Cindy, Is DH making the boxes out of plywood? Plywood will de-laminate when wet. It's used on the bottoms of table top boxes because it is strong, with sheets going up and down, and left and right. Make sure the plywood is formaldehyde-free for garden boxes. If he wants to coat the boxes, use UNBOILED linseed oil. My DH sometimes does more to a project than I originally ask him to do. Like he's building a house instead of chemical-free, organic as possible, garden structures.

cindgborgg 1/31/2014, 6:12 pm

I have to say my husband does go overboard sometimes on projects. Like he wanted to make it easier for me and made raised beds so he put plywood on bottom and he sealed them. Now I know better solutions thanks to everyone's response. I had a question on the plywood bottoms making the sheets go up and down and left and right I am not sure what that means, can you explain.

Thanks,

Cindy

**sanderson** 2/1/2014, 1:45 am

Cindy, If these are raised beds and he put plywood on the bottoms, it makes sense to me now. He can cut a new, interior sheet of thinner plywood and set that one down on the sealed one. That will provide a fairly good barrier. Water will tend to go downward, not upward to the veggies. Make sure there are little drainage holes drilled through both sheets.

Now let's see if I can describe plywood a little better than I did. Plywood is made with thin sheets of wood, pressure glued together. The grains of every other layer go in a perpendicular direction so the final project in uniformly strong in both directions. Hope this helps.

http://www.madehow.com/Volume-4/Plywood.html

cindgborgg 2/1/2014, 2:57 pm

Thank you that makes sense now.

Cindy

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Is Thompsons water seal safe to put on plywood bottom of SFG?

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