Water sealing with drylock?

[Mavrick813]

FWIW: I put 9 coats of drylock on the walls in my basement over the summer. That was after they were treated for mold, and Acid Etched. And yet again I am dealing with seepage this year. I wouldn't trust drylock to seal a plywood fishtank under any circumstances. Those of you that have tried it and it's working out. G/L to you.

Mike

 

[wheatgerm]

this is the product i bought... it was the only fiberglass they had at my lowes at the time and the reason i am putting it on first is because it filles the corners really well, also at the time i didnt realize i had leftover zavlar so i was planning on putting a few coats of fiberglass down then something to topcoat (like drylock) so i would have double coverage... on the side of this can it says "CONTAINS: polyester resin, styrene monomer..... from my understanding of 100% watersealing with fiberglass it would need to be "epoxy" based not poly based

 

[quovadis]

From what I know it is intended for concrete, but it does indeed stick to wood(not sure about poly/fiberglass though). In addition to the experience w/the 180G, I also have had a 75G tank w/a cracked side panel for the last two years. I cut a 3/4" panel of ply and coated it on both sides w/the drylok then siliconed it internally. It's been submerged for the majority of this last two years and I haven't noticed any peeling of the drylok or leaks of any sort.

HUH lucky you Drylock is unreliable at best even when used on intented surfaces I have recently sealed the inside of a poured cement large tank w/drylock //the creamy white paint looking type/// as we speak I am experiencing peeling of all over the tank BOY I AM PISSSSSSSSSSSSSSSSSS///luckily the project is insured....

 

[imusuallyuseless]

Sorry to hear of your misfortunes w/the product. Hopefully the OP can get everything sorted out to keep his project rolling. Anyway, best of luck wheatgerm

 

[CJH]

this is the product i bought... it was the only fiberglass they had at my lowes at the time and the reason i am putting it on first is because it filles the corners really well, also at the time i didnt realize i had leftover zavlar so i was planning on putting a few coats of fiberglass down then something to topcoat (like drylock) so i would have double coverage... on the side of this can it says "CONTAINS: polyester resin, styrene monomer..... from my understanding of 100% watersealing with fiberglass it would need to be "epoxy" based not poly based

Yeah, there is no polyurethane in that stuff. It's just regular old orthophthalic polyester. I'm not sure if it's waxed or unwaxed. Does the last coat you put on feel tacky at all?

You're right that it's technically not "100% waterproof" but neither is epoxy or any of the sealers people discuss on this forum regarding sealing plywood tanks.

Heck, even high grade acrylic isn't 100% waterproof by definition. It has some degree of moisture permiability and is not 100% vapor resistant. But it still holds water.

Polyester is more water permiable than epoxy or acrylic but it can and does provide sufficent water proofing for a plywood tank.

My bigger concern is that you didn't use any fiberglass reinforcement with the resin. Polyester can be a bit brittle and it's a really good idea to reinforce the corners.

Can you go back and do more coats but use some matting or cloth?

I like working with cloth better than matting and there is some evidence in the boat industry that cloth reinforcement absorbs less moisture than matting. And it takes less resin to wet out cloth than matting. But at this point either is better than none.

 

[wheatgerm]

i have 3 layers on all the corners of the sump.. i put the first layer down, waited until it was tacky and almost dry then i took mesh drywall tape and put it in the corners then i put another coat on... after about 6 hours it was totally smooth and so i lightly sanded it and just now walked in from putting the 3rd and final coat on. i added about 10% more harderner on the final coat just to make sure i had enough for it to dry real quick and be plenty hard hopefully by tonight ill start putting my zavlar on.. im not worried about this proccess at all, its the exact process that i built my 320 with and that was alot more pressure and held fine

 

[Clay]

I have Drylock in the bottom of my stand (4 coats with a roller), but I don't know if I would trust it to waterproof the inside of a tank...

I sealed the corners of mine with some kitchen/bath silicone, so I think it gives me a relatively decent amount of protection against the occasional spill inside the stand. I don't know about long term submerged usage though.

 

[CJH]

Sorry, I misread. Somehow I thought you didn't have enough zavlar for the tank and we're still thinking you'd need something else. With polyester you really don't assuming it's properly reinforced.

The idea that polyester isn't 100% waterproof and therefore needs another topcoat is a misconception that has been around for about twenty years.

 

[wheatgerm]

so just to be clear, your saying i could seal my sump with nothing but the gallon of fiberglass resin that i bought? and at the time i started this sump i thought i had ZERO zavlar this is why i bought the fiberglass in the first place.. however now i will have double coverage.. and it will be that much stronger so no harm done in using 2 products that work well with eachother IMO

 

[CJH]

so just to be clear, your saying i could seal my sump with nothing but the gallon of fiberglass resin that i bought? and at the time i started this sump i thought i had ZERO zavlar this is why i bought the fiberglass in the first place.. however now i will have double coverage.. and it will be that much stronger so no harm done in using 2 products that work well with eachother IMO

Obviously I can't say for sure if your tank will hold water, I can only tell you that others have with just ordinary polyester resin "painted" on plywood walls. Since you have some mesh tape in the corners there is a chance you'll be okay. It wouldn't be my first choice to waterproof plywood but it has been done.

But if you have enough Zavlar to coat it then the double coverage is a good idea. Really this basic concept makes a lot of sense. Resin plus some reinforcement tape to make a laminated, composite-type structure and then a flexiblee topcoat in case any micro cracks that may develop.