Epoxy paint on fiberglas

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Old 04-15-16, 04:12 PM
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Epoxy paint on fiberglas

I have to paint a bare concrete surface ( garage floor and surrounding exterior area) and also a balcony fiberglas floor.
Can the leftover epoxy paint used for the concrete surface( garage) also be used on the fiberglas surface of the balcony ?
People at the hardware store say that I cannot do this. I don't understand why. May be it is a gimmick to sell me a 2nd gallon. I'd like to kill two birds with one stone and save some money.
At the worst, I can try it and if it doesn't work, I'll do it over again next year. No big deal. Should I try or am I wasting my time ?
If I cannot use the same paint, which paint should I use for the fiberglas surface?

Do I need a primer or just a good sanding of the fiberglas?

Thanks

Franco
 
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Old 04-16-16, 03:54 AM
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There are a lot of different epoxy paints so we'd need to know which one you intend to use. Have you read the label to see what the manufacture recommends?

Some epoxies require a special primer, again read the label. Paint won't go far on unsealed concrete. What type of coating [if any] is currently on the fiberglass?
 
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Old 04-16-16, 06:10 AM
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Many epoxy coating will yellow in the sun. Some coatings recommend interior use or areas protected from sun only.
 
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Old 04-16-16, 10:48 AM
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The paint I am going to use for the concrete surface and, if possible, for the balcony fiberglas floor, is the Behr Concrete and Garage Floor paint, described as "1 part enamel". Actually, it is not even a garage and we don't park the car on it. The unfinished concrete is a part of the foundation, with the steps leading to the half-basement apartment. The area is outdoor, but under the 1st floor deck, so it is not exposed directly to the elements.

The instructions do not require to seal the concrete before applying the paint, neither do they mention a primer.

I am unable to determine if the fiberglass floor of the balcony has been painted over or not. It has a grey color, which I believe is premixed onto the fiberglas lamination, but I am not sure.

As I said , I am willing to try the concrete paint of the garage on it, after cleaning, sanding and priming the fiberglas surface, but I just want to know what to expect: if the paint will peel off or crack after days or a even a few weeks, it would be pointless. On the other hand, if at worst it can last a winter or longer , I don't mind redoing the work with the proper paint, maybe a marine epoxy paint. No big deal. The surface is small, only about 30-40 sqft including the threads and it is not a heavy traffic area. We are just two people, going in and out a few times a day !
Any comments?

Thanks

Franco
 
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Old 04-16-16, 01:35 PM
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I'm not very familiar with Behr coatings but it sounds like it might be ok over the fiberglass. Is the fiberglass fairly solid? or does it have some give?
 
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Old 04-16-16, 03:17 PM
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Thanks

Yes, most definitely the fiberglass surface is solid, very even and flat and doesn't look like wobbly or giving in.
You say it might be O.K. I appreciate your caution. I'll take a chance.

What worried me at first is that two different major stores ( Home Depot and Rona in Montreal) made it look like there is some incompatibility or inherent lack of adhesion between fiberglas and common paints, even the epoxy based ones. They said that an epoxy-based marine paint would do the job. Well, fiberglas is fiberglas. I don't see why the fiberglas of a ship's hull would take an epoxy paint and not the fiberglas of my balcony, aside from the UV issue, which doesn't worry me here.
Either they were wrong or wanted to sell me a 2nd gallon.
Time will tell who was right.

Thanks for your help

Franco
 

Last edited by ittiandro; 04-16-16 at 03:40 PM.
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Old 04-16-16, 05:24 PM
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You keep saying "epoxy" but the paint you mention is an enamel. They are two very different things.
 
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Old 04-16-16, 06:02 PM
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I don't know where you get the idea that this is an enamel, neither do I know what is the difference. .
Be it as it may, I call it " epoxy" paint because this is the description on the can I just bought:
" 1 part Epoxy- Concrete & Garage Floor Paint"

Franco
 
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Old 04-17-16, 04:29 AM
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Generally epoxy denotes a 2 part coating which includes a catalysis. Without the catalysis the epoxy won't dry correctly, once the catalysis is mixed in the coating has a set pot life after which any unused mixed portion must be discarded. I know some manufactures claim a 1 part epoxy but as far as most of us are concerned they are really just an enamel ..... with epoxy added to the label to make the consumer think it's tougher than other enamels.

Most quality paints [various types] will adhere to fiberglass as well as they will any other substrates with the same texture [slick, rough, etc]
 
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Old 04-17-16, 07:38 AM
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I gather by catalyst you mean something like the separate hardener you add to the fiberglas resin.
My “ epoxy” paint does not have any separate catalyst to add to it, but I have seen in the store a very expensive epoxy paint, three times more expensive than the one I bought. Probably this was the “ two part” coating you referred to.

Do you mean then that the paint I bought, which you call enamel, has no no epoxy inside, in spite of the “ 1 part epoxy “ description? If so, it sounds like Behr are engaging in some kind of misleading advertising. I doubt it, though, because they are a reputable company and their line is carried by major retailers like Home Hardware. There must be epoxy inside, probably not as effective as the catalyst formula, but still epoxy.

Anyway, this is probably a moot issue now, if you say that, epoxy or not, all the quality coatings/enamels should adhere to fiberglas as well. I trust your opinion. I’ll give it a try and let you know how it works out, if you are interested.

Thanks

Franco
 
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Old 04-18-16, 03:22 AM
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A lot of the terminology in the painting industry doesn't have strict definitions. For example, semi-gloss paints have different sheen levels dependent on both manufacture and line of paint. Being a painter and not a chemist I don't know what the exact definition of epoxy is but have always considered it to be a two part coating, generally oil base but there is also a latex version. Epoxies have always been considered to dry to a tougher finish than enamel [even though the dried product may look the same] Behr isn't the only paint manufacture to play fast and loose with the epoxy terminology as I've seen other coatings that claim to be an epoxy but don't have a catalyst.

It's always nice to hear back on how any project turns out It both verifies that our advice is correct [or not ] and helps those who read the thread later.
 
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Old 04-18-16, 01:09 PM
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After reading Marksr's post I realized I didn't actually know what the definition of epoxy was either did some research and came across this statement "In general, uncured epoxy resins have only poor mechanical, chemical and heat resistance properties. However, good properties are obtained by reacting the linear epoxy resin with suitable curatives", in this article https://en.wikipedia.org/wiki/Epoxy. It appears by reading it that you can definitely have the epoxy based materials in a one part product like you have but it will not have the desired properties compared to a 2 part epoxy product.
 
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