Liquid Rubber vs West Systems

I believe the liquid rubber goes on at 20-30 sq ft per gallon. So figure out the square footage of your tank (bottom, sides, back, trim around front, and any top braces) and that will tell you how many gallons you need.

I'm thinking that once you include shipping (if you need it shipped), then the Liquid Rubber will probably cost about the same... not including the fiberglass.

Fiberglass cloth is not specifically necessary. The wood is the strength of the epoxy. The seams and corners it would help, and you may be able to get away with drywall tape. I am using sweetwater epoxy for my 240. With SW epoxy you get a coverage of apx 100 sq ft per gallon. So for 1 gallon kit I am getting complete coverage, plus ply filter, and have left over. Plus I do not have the potential problems of sealing in the glass that has been noted, as well as more than 1 color.

Both products are very good, and am not discouraging the Zavlar, just do some research from the manufacturers before you decide.

Liquid rubber does not stick to glass so it cannot be used to seal the viewing window. It also does not stick to silicone and silicone does not stick to it. I discovered these things when trying to sealing in my viewing window. My viewing window is still a work in progress. My window sits in a frame, I ended up having to use fiberglass resin around the frame to have something for the silicone and LR to bond too. This is drying right now and I should know if it will work in a couple of weeks. As far as how many coats of LR, I have about 10 coats on my tank which seems to be good, what you are looking for is a thinckness of about 2 credit cards. For a 700G tank, you will need 5-6 gallons I'm guessing. It is recommended that you use the mesh drywall tape in the corners with LR but I didnt do this. My tank was built with an external frame and I didnt see the need for it. There is a link at the bottom to my build....

Joey did a build using LR and used silicone to silicone his glass to the LR. I did some testing after my initial fill failed and could not get silicone to stick to LR to get a good seal. I am not sure what Joey's secret was but I was able to pull LR from the silicone easily. Like I said earlier, I think I have found the answer, fiberglass resin around the frame of the viewing window. It was a $15 fix. I will know for sure when I fill in a couple of weeks.

Try to find some of this stuff http://www.antel-uk.co.uk/tds/as01.html that will work to seal any gap 1st then appply the liquid rubbber, it should hold. If you can find it in your area then these guys might ship hope it helps and good luck dude

kwantz;4015008; said:

Ok im about to start my 700 Gallon build.
The liquid rubber is alot cheaper than the west systems epoxy + fiber glass. It would run me just a little over 200 dollars to use west systems and the fiber glass.

the liquid rubber Zavlar would run me approx $38.00 per Gallon. Which is a lot cheaper. Thats the whole point in with DIY is to save a ton of coin.

Would I be able to get away with 1 gallon of it? or would I need more?

I figure with using liquid rubber it would eliminate the cost of having to use fiberglass which is 12 dollars per yard at my local marine shop.

Click to expand...

Living in Canada and being able to get the LR for $38 per gallon would make me lean towards that over epoxy. But before you make that decision you should compare costs more closely, IMO.

Comparing coverage rates is not always a good idea because sometimes there is an assumption about what substrate is being covered and some substrates take up more sealant that others due to surface texture.

The thinnest dry mil thickness I have heard for LR is 60 mils. LR is about 55% solids by weight so probably around 75% solids by volume.

So that means to achieve a 60 mil dry thickness one would have to apply about 80 mils total wet thickness. 75% of 80 mils is 60 mils.

So that means a gallon of LR will coat about 20 sq. ft.

The thinnest dry mil thickness I have heard of for West Systems is 10 mil dry film thickness. West Systems is 100% solids so by industry standards the shrinkage in film thickness is considered zero.

So that means a gallon of West Systems or other 100% solids Marine Epoxy resin will coat 160 sq. ft.

So while the LR may be cheaper per gallon, it takes up to eight times as much to waterproof a plywood tank.

This assumes the same amount of fiberglass reinforcment used along joints and the same type of plywood being coated. West Systems does not recommend full fiberglassing on the inside of plywood tanks. LR recommends cloth along the joints on the interior. I would consider the cost of fiberglass to be about equal.

Now with all that said, I personally would use more than 10 mils epoxy to waterproof a tank. I would probably shoot for 20 mils. But that still means you need 1/4 the epoxy as LR.

So if you're getting LR for $38 and West Systems for $152 per gallon the cost will be about the same. I don't know what West Systems goes for up in Canada but I'm guessing it's a bit cheaper than that?

Both are zero VOC so consider that equal.

Epoxy requires accurate mixing and a pretty quick work time while LR is a single component mix with a longer open time.

LR will take multiple thin coats to achieve a dry film thickness of 60 mils while epoxy will take just a few coats to achieve a film thickness of 20 mils.

If you post the square footage of your tank interior minus the window cutout I'll be happy to calculate the amount of epoxy and LR you would need.