Link for what epoxy to use for plywood tanks?

[garhog]

its recommend at 20 mils for max moisture resistance . half as thick so twice the coverage I would think

 

[CJH]

its recommend at 20 mils for max moisture resistance . half as thick so twice the coverage I would think

Half as thick so twice the coverage is not how it works because you also have to calculate how much the product shrinks as the drying process occurs. Epoxy resin is 100% solids so all of the volume of the gallon ends up as your dry mil thickness.

Epoxy Paint, like Sweetwater, are about 60% to 70% solids by volume so your dry mil thickness is 60% to 70% of your wet film thickness.

Regardless, when I spoke to West Systems the rep told me that 20 mils was really only necessary to make sure your low spots had 10 mils.

If you apply epoxy at the volume that gives you 10 mils you'll end up with some spots with more, some spots with less. Shooting for 20 mils means it's unlikely you'll have less than 10 mil anywhere.

Again, I want to stress that products that are 100% solids and require thinner dry mil thickness are not necessarily better. They are cheaper, however.

 

[BoCoMo]

The Pond Coat from Permadri sounds like a fantastic product but I'm not sure it would be high on my list if cost were a primary concern.

Pond Coat has been mentioned on this sight as costing anywhere from $46 to $57 per gallon depending on how much you order. That's before shipping and I think for simplicity we'll not factor that in for now as it's location dependent.

But I calculate it at 75% solids by volume (55% by weight) so it needs to be applied thicker to achieve that final dry mil thickness of 40-60 mil recommended by Permadri.

So the $46 to $57 you're paying "per gallon" of Pond Coat is really only for 75% of a gallon.

So really with Pond Coat you're paying $61 to $76 per gallon of solids.

Still pretty good, in my opinion.

But epoxy resins only require a dry mil film thickness of 10 to 20 mil to form a waterproof membrane and they are 100% solids so everything you're paying for ends up forming that membrane.

For simplicity let's say Pond Coat needs a final dry film thickness THREE times that of epoxy.

What this means is that is as long as a 100% Epoxy resin product is less than $180 to $225 per gallon it will be cheaper than Pond Coat.

I'm not writing this to say Pond Coat is a bad product. I am writing this to show how you can't simply look at the cost per volume when comparing a products that vary in percent solids and in recommended dry mil thickness.

Personally I find the whole concept of Pond Coat very intriguing.

But I also consider it to be a very expensive product.

Spoken like an investor.

Half as thick so twice the coverage is not how it works because you also have to calculate how much the product shrinks as the drying process occurs. Epoxy resin is 100% solids so all of the volume of the gallon ends up as your dry mil thickness.

Epoxy Paint, like Sweetwater, are about 60% to 70% solids by volume so your dry mil thickness is 60% to 70% of your wet film thickness.

Regardless, when I spoke to West Systems the rep told me that 20 mils was really only necessary to make sure your low spots had 10 mils.

If you apply epoxy at the volume that gives you 10 mils you'll end up with some spots with more, some spots with less. Shooting for 20 mils means it's unlikely you'll have less than 10 mil anywhere.

Again, I want to stress that products that are 100% solids and require thinner dry mil thickness are not necessarily better. They are cheaper, however.

How do you measure/gauge how many mils thick it is?

 

[CJH]

How do you measure/gauge how many mils thick it is?

They make guages to measure wet mill thickness of applied paints, sealers, etc.

But for the most part it's easier to know how much sealer needs to be applied over the entire surface in order to achieve the required mil thickness.

So I just calculate it myself, knowing that that there are 231 cubic inches in a gallon and a mil is equal to 0.001 inch.

I also adjust depending on how textured/porous the surface is. Like I said before this can be one of the bigger problems from going with recommended coverage rates.

 

[garhog]

They make guages to measure wet mill thickness of applied paints, sealers, etc.

But for the most part it's easier to know how much sealer needs to be applied over the entire surface in order to achieve the required mil thickness.

So I just calculate it myself, knowing that that there are 231 cubic inches in a gallon and a mil is equal to 0.001 inch.

I also adjust depending on how textured/porous the surface is. Like I said before this can be one of the bigger problems from going with recommended coverage rates.

is the 40 mil recomendation for liquid rubber a wet thickness. it would make sense as it would shrink down when dry and that why it has to go on so thick if not you would really need a lot

 

[BadOleRoss]

Pond Coats appears to be a very effective product and it seems to be very easy to apply and I like that it remains flexable. Pond Armor looks like a pain in the tail to apply and it seems pretty easy to leave voids and or pins holes. TheFishGuy had more than his share of troubles with Pond Armor. Cost for me would not be a factor over the performace of the product. If it cost 2-3Xs as much but gave me a leak-proof tank it would be worth it! I admire you guys for breaking down the solid percentages and mil thickness but that just too much thinking for this ole man. I just want something that is as easy as possible and works the best.

 

[CJH]

is the 40 mil recomendation for liquid rubber a wet thickness. it would make sense as it would shrink down when dry and that why it has to go on so thick if not you would really need a lot

I read it as dry mil thickness, but it was not specifically written that way.

If anybody finds out otherwise I'd be happy to redo the calculations.

Would also like to know the actual percent solids by volume.

 

[CJH]

Pond Coats appears to be a very effective product and it seems to be very easy to apply and I like that it remains flexable. Pond Armor looks like a pain in the tail to apply and it seems pretty easy to leave voids and or pins holes. TheFishGuy had more than his share of troubles with Pond Armor. Cost for me would not be a factor over the performace of the product. If it cost 2-3Xs as much but gave me a leak-proof tank it would be worth it! I admire you guys for breaking down the solid percentages and mil thickness but that just too much thinking for this ole man. I just want something that is as easy as possible and works the best.

I agree. As much as I like epoxy, I'm actually willing to pay more for diluted epoxy paint since it is so much easier to work with, assuming you can deal with the solvent vapor. And for the record I have used both epoxy resin and epoxy paint to seal tanks. I have not used West Systems with the 207 which is said to make the product much easier to work with. But I have used regular West Systems plus maybe three other marine resins.

And I feel the same way about these elastomeric emulsions like the Pond Coat being discussed here. They would be worth every penny to me if they work as advertised.

But the original post in this thread dealt with cost concerns and as I read it the Permadri product was mentioned as an affordable alternative. That's why I chimed in.

 

[garhog]

I appriciate the breakdown. though I already am using west system it Is good to learn as much as you can about all type of sealants. everyone has there own preferences some durability. ease of application or cost. I don't think that any wins in all so it comes down to the individual to decide what is best for his/her app

 

[CJH]

I appriciate the breakdown. though I already am using west system it Is good to learn as much as you can about all type of sealants. everyone has there own preferences some durability. ease of application or cost. I don't think that any wins in all so it comes down to the individual to decide what is best for his/her app

Well said. There is no perfect plywood tank sealant. They all have their tradeoffs. To your list of durability, ease of application and cost, I'll add two of my own:

1) Silicone adhesion

2) Repairability.

I suppose a third will be availability once the new VOC regulations go into effect in 2011.

All we may have left are Liquid Rubber and epoxy resins since both are zero VOC.