"Pros and cons" experienced comments please
- Thread starter TheBlackRayGuy
- Start date
I assume by "fiberglass" you mean you plan to do a build coat on all surfaces with some sort of fiberglass reinforcement (mat, cloth or roving) wetted out with polyester or vinyl ester resin?
And then you plan to put a gel coat on top of that?
And then you plan to put yet another sealer on top of that?
At the very least I'll comment that if you want to combine polyester + fiberglass with some other sort of sealer then the gel coat layer is really unnecessary and might even inhibit the bonding of subsequent layers, depending on the type of gel coat used.
Fiberglass plus polyester resin alone is a traditional way of building plywood tanks. Back in the late 80's I saw plywood tanks that had been built in the late 60's with nothing but fiberglass cloth, mat and polyester resin. No gel coat.
Somehow over the years it has gotten a bad reputation to the point that some believe it isn't sufficiently waterproof nor is it safe for fish. Yet there are plywood builds on this site sealed with nothing but orthophthalic or isophthalic polyester resins and some fiberglass reinforcement.
For sure if you want to build up a thick layer of fiberglass reinforcement then polyester resin is an inexpensive way of doing so. But understand that you can also use epoxy resin (note resin, not expoxy paint) to wet out and build up a fiberglass layer. But it will be more expensive if you use equal amounts (more on that later).
Comparing 100% epoxy resin to a decent quality polyester, there are some differences to consider.
Polyester will be about 1/3 to 1/2 the cost of a cheaper epoxy resin. Maybe closer to 25% the cost of an expensive epoxy resin, especially if you have to have the latter shipped in and the former can be purchased locally.
But this cost difference can be reduced when one considered that less epoxy can be used to build up a comparable strength composite layer. How much less? Some companies that sell both report as much as 50% less epoxy and cloth can be used to build an equally strong layer. But the reality is that many building plywood tanks want to go overkill and they apply much more than needed so you have to ask yourself if you're really going to do all of the calculations or are you just going to keep layering on fiberglass and resin until you feel like it's enough?
There are some working differences between the two. Polyester has a strong styrene smell which can be a problem in enclosed areas. I don't mind the smell in small amounts but for a large project it can be too much. Epoxy resin has nearly no odor but can cause exposure allergies.
Polyester generally sets up very quickly, although that can be controlled to some extent. Some people do like how quickly polyester sets up, especially on vertical surfaces which are subject to sag. Others find epoxy easier to roll out, especially since it doesn't gel up the same as polyester. Beginner boat builders tend to prefer epoxy.
Comparing un-reinforced polyester to un-reinforced epoxy, epoxy will be more flexible and more durable and will waterproof at a thinner layer. Once you starting adding in fiberglass a lot of these differences become pretty trivial, IMO. To address an eariler post, cured epoxy is more flexible without fiberglass. It becomes stiffer and stronger once fiberglass is included.
Polyester is more UV resistant if you're considering an outdoor tank or a porch tank. But even under metal halides or directly by a window epoxy holds up to the sun. It's really direct, unfiltered sunlight that is a problem.
I have used polyester + fiberglass, epoxy + fiberglass and just epoxy without fiberglass to seal plywood tanks. I've also used epoxy paints like Sweetwater to seal plywood tanks. All have their pros and cons. I will say that epoxy paints are different enough from 100% epoxy resins that they really shouldn't be lumped together.
While I have some experience with bituminous emulsions (i.e.Liquid Rubber"). I have not used them on plywood much less plywood tanks.
Oh yeah, my favorite epoxy resin is West Systems with the thinner/clearer hardener. It really is noticeably easier to work with but it's also more expensive. Based on price and what appears to be quality customer service and really good advice about plywood tanks it would be hard for me to look past Max ACR today. I have not used their product nor do I have any affiliation with them. I've just been impressed with the advice they've been giving out to plywood tank builders as reported on various forums.
But of course if I were building a tank today I might just use polyester. It would depend on a few factors. Only sealer I would rule out is Sweetwater due to hazardous material shipping charges. If I lived in Florida I'd consider it as well.
Thank you, I really appreciate this^^
And you hit the nail on the head, what I plan to do is build my wood structure, then line it with fiberglassing as the same form as building a BOAT HAUL or a BATH TUB" which are both very similar constructions, an both last very long.... As fiberglass alone is not designed to be submerged or wet for its lifetime that's where I thought about gel coating" again like BOATS an BATH TUBS" as gel coats main design was to be submerged for it's lifespan.
Idk if rubber or epoxy will bind with gel coat either I guess I will do a sample piece and try?
I look at it as a security I gues I know constructing it like an inside out boat haul or bath tub is a perfect design and I have no doubts that that alone will hold water 100% for life as boats float for 50 years easy and bathtubs outlast the house they are in.... The liquid rubber an epoxy questions I have are just for piece of mind I guess?
I really appreciate your info if you have any suggestions or other ideas please do contact me or just keep replying to this post
Thanks
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MAS Epoxies are non blushing and is what I would use. http://www.masepoxies.com/ The problem with using either of ester family of resigns is they take years to fully cure (actually can take up to 25 to 30 years for them to completely cure out, sounds crazy don't it) and the flashing of the chems takes along time, and gel coat is nothing more than Polyester resign with alot of solids and binders in it
Thank you, I really appreciate this^^
And you hit the nail on the head, what I plan to do is build my wood structure, then line it with fiberglassing as the same form as building a BOAT HAUL or a BATH TUB" which are both very similar constructions, an both last very long.... As fiberglass alone is not designed to be submerged or wet for its lifetime that's where I thought about gel coating" again like BOATS an BATH TUBS" as gel coats main design was to be submerged for it's lifespan.
Idk if rubber or epoxy will bind with gel coat either I guess I will do a sample piece and try?
I look at it as a security I gues I know constructing it like an inside out boat haul or bath tub is a perfect design and I have no doubts that that alone will hold water 100% for life as boats float for 50 years easy and bathtubs outlast the house they are in.... The liquid rubber an epoxy questions I have are just for piece of mind I guess?
I really appreciate your info if you have any suggestions or other ideas please do contact me or just keep replying to this post
Thanks
Sent from my iPhone using MonsterAquariaNetwork app
Sent from my iPhone using MonsterAquariaNetwork app
Permadri will bond to just about any surface including fiberglass. Most coatings will NOT however bond to it.
Wow alot of people have misconceptions about fiber glass. a Fiber glass does absorb water even when gel coated, gel it self if very pores , it is not able to spend it entire live span wet .b the chems used it are harmful to fish and take years to flash. c if you dont get the ratio resign to cloth just right it becomes either bridle(with to much resign) or full of air bubble( not enough resign to fill the cloth) and the resign has no strength at all with out cloth and will crack . and that just for the start...I work with it everyday and have been for the last 25 years...... not good for Tank builds
It sounds like you're thinking about the plywood less in terms of structure but more in terms of a form and possible the exterior look? Is that right?Thank you, I really appreciate this^^
And you hit the nail on the head, what I plan to do is build my wood structure, then line it with fiberglassing as the same form as building a BOAT HAUL or a BATH TUB" which are both very similar constructions, an both last very long.... As fiberglass alone is not designed to be submerged or wet for its lifetime that's where I thought about gel coating" again like BOATS an BATH TUBS" as gel coats main design was to be submerged for it's lifespan.
Idk if rubber or epoxy will bind with gel coat either I guess I will do a sample piece and try?
I look at it as a security I gues I know constructing it like an inside out boat haul or bath tub is a perfect design and I have no doubts that that alone will hold water 100% for life as boats float for 50 years easy and bathtubs outlast the house they are in.... The liquid rubber an epoxy questions I have are just for piece of mind I guess?
I really appreciate your info if you have any suggestions or other ideas please do contact me or just keep replying to this post
Thanks
Sent from my iPhone using MonsterAquariaNetwork app
In that case I think you should use a mid range lay-up polyester. Look and see what you can get locally first. Buy in bulk if you think you'll need 5 gallons.
With the money you save on polyester (vs. epoxy) I would invest in fiberglass cloth and/or roving instead of mat. Mat is cheaper but takes more resin to wet out and boat builders believe it is more likely to compromise the water proofing since the random fibers of the mat are thought to provide a path for water to migrate into the composite layers. There are good articles about this online. A lot of information to wade through but if I were building a tank I'd go back and read through it again.
I understand your thoughts about constant submersion for a polyester/fiberglass composite but I'm still confused as to why you plan to use both a gel coat AND another sealer (epoxy or liquid rubber).
I would instead think of the gel coat as the final layer. Maybe look into epoxy gel coats. I've never used them but they're supposed to adhere well to polyester and provide a more durable final layer. My only concern with them is I don't know if they're considered repairable? With an investment like a plywood tank I think you always want to consider the repairability of the final layer. Like if you used a liquid rubber type product you could only go over and repair it with more of the same. You couldn't go back and go over it with fiberglass and any type of resin.
Likewise if your final coat is epoxy you can't go back over it with polyester. Epoxy bonds well to cured polyester better than polyester bonds to cured epoxy.
I read an excellent online article on gel coats in the past year or two but didn't save it. There were a lot more choices for gel coats than I was previously aware of.
Again, I don't think that top coating fiberglass and polyester is absolutely necessary. But I can certainly appreciate your wanting to do so. I only question putting down "gel coat" as a middle layer between your intial comosite layers and your final coats. Some gel coats are designed to have a low surface energy so they're easy to clean, etc. They may not allow for good adhesion of your final coats. Some gel coats are harder to repair than others, etc. Others are easier to buff out than others but "might" be more likely to blister. This is where you need to stop listening to me and start reading on your own.
But I will say that if you don't want to use a gel coat as a final coat then I'd consider skipping it altogether. Unless you read something where it actually ehances the bond to what you want to use as your final coat.
