Epoxy Tricks

[Howard]

Back to building those plugs for glass boats. The guys who do that are true experts at the blocking techniques PAR has described above, except they get to use really soft, easy to sand fairing products like Bondo. Not thickened epoxy. They only need a perfectly smooth, flawless surface......it does not have to be durable. So the molds they build are just about perfect as far as a fair symmetry is concerned. When you sight down a glass boat, you don't see many (any?) defects. Just a smooth mirror finish. We try to do the same thing, except our surface also has to be durable, so we are using thickened epoxy to fill any defects. If you then sprayed or rolled on a heavy gel coat finish, you may or may not end up with that same level of finish. Unless you were willing to accept a work boat finish, you might be back to fairing and blocking the gel coat. If you use paint instead.........the coatings are so thin, they tend to adhere to what is there, and won't distort anything, but will also not hide anything. If you have a flawless finish, you will see it. If not, you will see that too.  The two part LPU paint systems are durable. BTW, when the gelcoat on older boats does wear out or wear through from all the buffing and polishing, they don't recoat with gel coat. They paint them.

[Chick Ludwig]

Gel coat is a polyester or vinylester material. It is intended to spray against a mold surface before laminating with fiberglass and resin. It is not intended to paint on the inside surface. It is sprayed in to finish the surface of a fiberglass boat that has no inner liner. You'll notice that the surface is rough. Even if you do use it, and sand and buff it to a shine, it will oxidize and fade. On top of all that, it will not bond well to epoxy. Sometimes it won't even cure. If used to finish a wooden boat, it will crack and peel. I guarantee that you will not be satisfied with it. There are commercial additive such as Duratech that can be added to it to make it spray more like paint, but they are difficult to use and still won't give the durability or surface that you want. PLEASE still with the recommended products. (By the way, ask me how I know about gel coat!)

[Fishman38]

Sounds like you may have learned from the School of Hard Knocks.............

 

Thanks to all for the short course on gel coat, a term which I've heard most of my life when the subject of polyester and epoxy resins came up.  Now at least I understand where and why it's used.

[Scott Dunsworth]

When I am feeling a little down about my fairing skills, I just wall the docks and look at the larger fiberglass boats. Very few of them dont have some waves or dips.  Most small fiberglass boats ( 16 to 20 ) seem to be near perfect.

[PAR]

Most production boats aren't very fair, though they are usually quite smooth. The larger the boat, the harder it is to fair, which may be why they seem, less fair than smaller boats. I have seen high end custom builds, with flawless hulls, but these builds can afford the hundreds of hours in hull fairing, which is the real issue.

 

Plywood bent around into a boat shape, tends to be naturally self fairing. Seams and joints need attention, but large expanses of panels are relatively neat. Fairing is simply time and materials, assuming good technique. It's also one of those things that requires some practice, mostly so you don't make a career out of the job. This is where most back yard builders fall down -  the finishes. The finishes are only as good as the prep and fairing is difficult to do well, quickly and with a minimum of materials. I know one builder that advocates coating the whole hull, with a notched trowel of fairing compound. This is knocked down and the remaining grooves filled and knocked down. To me this is a huge waste of time and materials, with no appreciable gain.  I can see how it would identify high and low spots, but I can't see how it saves any time and certainly nothing is saved in goo.

 

Fairing sucks, when you don't know how to do it or are using a poor technique. I remember learning how to fair and damn I was bad at it. I remember doing a little skiff, several layers of compound and blocking primer and the shop boss told me to wet sand the final primer coat. When I did, I had to roll the boat outside into the driveway and I could see how truly bad I was. The shop boss laughed, knowing what I was about to find with the wet sand. I wheeled it back into the shop, dried her off and got out the "boogie board" again. Interestingly enough I wasn't very far off and a couple of more coats of primer, filled in the last of the lows. It's a learning process, for some a long one. Pretty much like sex actually. At first you could hardly satisfy yourself, but with some practice and instruction, you could eventually please a prom date.

[Dale Niemann]

Good luck Alex.  Your guy is the only person I have heard that believes in covering epoxy with gelcoat. 

 

Please let us know what happens if you try it. 

 

Personally, I think two part epoxy based paints hold up as good or better than gelcoat.

 

Dale

[SteveKos]

Varnished solid wood trim will maintain by simple sanding and recoat just fine without epoxy underneath it.

What about just priming with an epoxy primer? I bought one which is water thin and was recommended just as a primer under varnish.

[Hirilonde]

 

Varnished solid wood trim will maintain by simple sanding and recoat just fine without epoxy underneath it.

What about just priming with an epoxy primer? I bought one which is water thin and was recommended just as a primer under varnish.

 

My first question would be why?  What does it do that a thinned "primer" coat of varnish would not do?  Just because someone makes a product does not mean there is necessarily even the slightest reason to use it.

 

Next I would wonder what it is, the product that is?  Penetrating epoxies are just solvent thinned epoxies.  The result being that all of the characteristics that make epoxy what it is are compromised.  Is this stuff thinned epoxy?

 

For me to do something, I need evidence that their is a good reason to do it.  I have never seen nor heard of any particularly good evidence that epoxy under varnish on solid wood accomplishes anything better than the varnish does by itself.  I have found, from experience and from others, that trying to refinish wood that has epoxy under varnish is a royal pain in the @$$.

 

I am open to new ideas and new products.  But show me evidence first that it is an improvement. 

[PAR]

I agree in that bright work doesn't need to be any harder to do or maintain then it is. This are the most difficult finishes to have, so keep it simple. Some like epoxy under clear coats, I don't. It's bad enough caring for clear finishes, without the bother of epoxy, thinned or other wise. If you want more protection, then use a light sheathing (4 ounce or less), but straight or thinned epoxy isn't going to add anything to the durability of a clear finish, though it can add to the care of it.

[SteveKos]

 

 

Varnished solid wood trim will maintain by simple sanding and recoat just fine without epoxy underneath it.

What about just priming with an epoxy primer? I bought one which is water thin and was recommended just as a primer under varnish.

 

My first question would be why?  What does it do that a thinned "primer" coat of varnish would not do?  Just because someone makes a product does not mean there is necessarily even the slightest reason to use it.

 

Next I would wonder what it is, the product that is?  Penetrating epoxies are just solvent thinned epoxies.  The result being that all of the characteristics that make epoxy what it is are compromised.  Is this stuff thinned epoxy?

 

For me to do something, I need evidence that their is a good reason to do it.  I have never seen nor heard of any particularly good evidence that epoxy under varnish on solid wood accomplishes anything better than the varnish does by itself.  I have found, from experience and from others, that trying to refinish wood that has epoxy under varnish is a royal pain in the @$$.

 

I am open to new ideas and new products.  But show me evidence first that it is an improvement. 

 

 

Thanks H for that. I just read the manufacturer's (Norglass Paints) instructions again for the 2 pack varnish I'm using, and - surprise surprise - they don't actually recommend a primer under it at all. I was sold the primer by the salesman in the boat supply store (!! I'll be returning it - if I can find the receipt ). The manufacturer's guide doesn't even stipulate thinning the first coat, although they do say it can be thinned if wished (which I think I will, to get a better penetration into the timber). They advise appying the 2 pack coating straight over a good clean but unprimed surface.

 

Live and learn as they say! Just confirms again that you can't trust everyone in a boat supply store. I'll have to suss out the best store (and staff person) to consult for future projects, and even talk to the manufacturer to confirm recommendations.

 

I thought I was gaining in knowledge but I still find that there's so much mis-information around on all subjects, even from so-called 'experts',  that one could be forgiven for staying away from DIY. But thanks to forums such as this one the dangers of making huge un-correctable mistakes are minimized.

[Hirilonde]

I am glad my info helped.  There really is a lot of bad info out there.  I have followed my share as well.

. I just read the manufacturer's (Norglass Paints) instructions again for the 2 pack varnish I'm using, and .....

 

Ah, I thought you were using varnish.  That stuff isn't varnish at all.  it is a 2 part polyurethane.  I don't touch that stuff either, and for the same reason:  When it comes time that refinishing is necessary it is a royal pain in the @$$.  2 part coatings with pigment are easy to refinish as you simply sand it well, clean it and coat over.  The new stuff hides all the old stuff.  This does not work with clear coats over wood.  Everyone has to decide for themselves what to use.  I have come to the conclusion that you cannot petrify natural wood finishes, so I don't even try.

[SteveKos]

Ok. Well I think I might change to the one pack then. I still have enough left from my last build fpr the little areas I am needing it for. It's a couple of years old but it should be ok if I strain out any hardened bits. Not much needed.

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[PAR]

Clear coats fall into 4 basic categories - alkyd (traditional oil base), acrylic (water based or borne), traditional oil (Dutch oil, etc.) and polyurethanes. Oils (Dutch oil) have been discussed enough I think and at best, they're a distant second to the worst of the other 3 choices. Alkyds are the traditional oil varnishes, which take a day for each coat to dry and require a good bit of practice to "flow" down a nice coat. These coatings have seen some modernization in recent years, becoming harder and drying faster, but for the most part still can make a career out of varnishing up a boat. Acrylics have turned up and these are really much more like the polyurethanes, than traditional oil based varnish. They dry quickly are harder, have higher gloss and easy clean up. They're not quite as durable as solvent based polyurethanes, but better than traditional varnish. The polyurethanes and acrylics can be further divided into single and multiple part systems. These are usually catalyst systems (multi part types), requiring a base resin and hardener and possibly more (wetting agents, drying agents, special reducers, etc.). The automotive paint systems have a very good clear coat acrylic, that's rivaling the solvent based stuff. For topsides, I've been using these recently with good results. Lastly, are the true solvent based polyurethanes. They come in single and multiple part systems and are the most durable and costly of them all. The single part coatings are reasonably cheap, but some of the two and more part systems can cost a lot. For ease of use, the single part polyurethanes and acrylics are hard to beat. They dry fast, so multiple coats per day. They're hard, durable, better UV resistance and higher gloss. On the down side, if you let these finishes get away from you, the probability will likely force you to remove all of the finish, wholesale. They can be repaired, if dinged, but many find these types of repairs aren't as good looking as oil based varnish repairs.

[SteveKos]

Ok, this is where the boys leave the room (me). All I want is a finish that looks good, is reasonably durable and can be applied by a non-professional with passable results. It seems everyone you ask who's supposed to know has a different opinion. I think I'll just chose and have done with it. Life's too short to wring one's hands over which clear finish to put on a few bits of timber. Like with all things, there's no perfect solution to any problem, only different ones. Thanks for the advice and education, but sometimes just making a choice and moving on is the best choice.

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[LennieG]

Steve-

Well said! I appreciate the knowledge and advice in these threads and particularly the willingness of guys like Paul to help all of us. It is incredible!!!! With something like paint choices my head is spinning after awhile and I need to make a decision and move on, which I am about to do with paint, I hope

[Howard]

Looks to me like we need a paint thread of it's own?

 

Actual brand names that correspond to types? Pros and cons of each? Safety tips? Application tips? Interior vs. exterior? Paint and color schemes? All that just scratches the surface (pun intended).

[LennieG]

I think we have a paint thread. there's some cross over isn't there. With your help and Paul's, Howard, I am buying Rustoleum Marine Topside today, along with its primer, and testing my CB with it as you suggested. It is an oil based alkyd so I will proceed carefully but if it works it could save a lot of little hassles. It is cheap, available at Lowes, easy application, quick drying, safe vs LPU, and well regarded.

[LennieG]

A gentleman in a neighboring storage unit loaned me his "sand shark" tool. He is a woodworker and excellent craftsman with past boat repair experience. It is a great tool for knocking off dried epoxy on hull of boat. I may even be able to use it for flattening the bottom of the hull 1" for the surface of the keel. It is kind of a cross between a rasp and a sanding block and is aggressive , controllable and comfortable in the hands. I am trying now to source one for purchase but it may be discontinued....was once available at Ductworks.

Figured you'd be interested.

[Fishman38]

If it'll cut cured epoxy I could use one!  Got a lot of that to do.  The cutting surface looks much like a tool the drywallers used to use but with a different handle.  I've had it for years and never had much use for it.  I'll try it on the epoxy.

[LennieG]

Yeah mixed comments if you google it. Seems like it was a gimmicky tool that never got traction and was discontinued in 2006. I have so far found it useful, but you'll notice I have no pictures to post