Need to decide, epoxy, CPES, and/or Fiberglass?

Armada,

Personally, I've never been a fan of penetrating epoxies, a couple of times I have sanded parts coated with those kinds of products several months, and even years after application, and I can smell the solvents from the epoxy quite clearly. At least to my thinking, having those solvents trapped inside, and free to wander about the plywood that was coated cannot possibly be good for the adhesive holding the veneers together.

Thus, what I prefer to do, is to heat the substrate, (space heaters and plastic will do) and then mix a batch of good epoxy, (WEST system, or the like) and then heat it in a microwave for approximately two seconds per ounce, and then apply it quickly.

According to my (admittedly) simplistic thinking, at a certain stage of cure, when a solvent molecule leaves the coating film, it has to leave a microscopic pore behind it, and that pore leaves a locally effectively much thinner epoxy coating than the area surrounding it, and consequently, a degraded ability to withstand moisture.

Yoke.

 

Okay, lets break open the can of worms. Epoxy is 100% solids when cured, no trails left by solvents, no pores to be left open. Lets get back to chemistry 101.

First I'll answer your questions Armada. The only time epoxy treatments (CPES included, as it is epoxy) is if the pieces are encapsulated. This means true encapsulation, every side, every piece, each hole, notch, saw kerfs, dings, everything, must be coated, WELL or it doesn't work. Generally this means a lot more extra work, effort, materials and money, but it can be worth it, if it's done properly and most importantly of all THE COATING MUST REMAIN INTACT. Any breaches in the coatings will need be addressed right away or you'll null and void the process and possibly cause other issues to bite you in the butt. SO the answer to question 1 is yes, coat with CPES if you want (recommended on new construction), pay close attention to end grain and then put 'glass cloth set in epoxy over this (it will provide abrasion protection, though there are better products to use then regular 'glass)

Question two, any paint will do, though some, as you may guess, are much better then others. At the top of the list are the two part linear polyurethane's, next are single part poly's, then the modified enamels, the regular enamels and then the acrylics (latex) They also have some odd ball paints like one part epoxy (really just a modified enamel) and others, which I suspect are just fancy names for the same old oil based paint they've been selling for years.

Now, onto the hot plate about epoxy, CPES and the uses in boatbuilding.

Resin is the basis for epoxy and typically is diglycidol ether of bisphenyl A. Under the right conditions, bisphenyl A is a reaction of phenol and acetone. The "A" is acetone, "bis" means two and "phenyl" means phenol groups. Bisphenyl A is the product from a chemical combining of two phenols with one acetone. Ya with me so far. Unreacted acetone and phenols are stripped off the bisphenyl A and then reacted with a material called epicholorohydrin (there will be a spelling test in your next class). This results in two glycidol (di) groups sticking to the ends of the bisphenyl A molecule, which is then called diglycidol ether of bisphenyl A and is the basic goo we call epoxy resin. It is these glycidol groups that react with the amine hydrogen atoms in hardeners to generate cured epoxy resin. This basic resin can be modified for different properties, harder, softer, more brittle, less brittle, more flexible, less flexible, higher breaking strength, etc., etc. etc. and it is this that becomes proprietary among the epoxy manufactures.

Had enough yet? Onto the hardeners, which are commonly polyamines (room temperature cured epoxy). Here it comes, wait for it . . . they are organic molecules containing two or more amine groups. Some manufactures use this little fact as a selling point to bolster it's place in the boatbuilding industry, but it's bull **** really. The keyboard you are about to use to cuss me out for all this dribble, likely also has organic compounds in it's manufacture, so what. Amine groups are a lot like ammonia in structure except they are attached to organic molecules and this similarity causes epoxy hardeners to have a notable ammonia like odor. Once in the open air this effect disappears quickly because of the high vapor pressures of the polyamines, though in closed in spaces it can linger.

Reactive amine groups are nitrogen atoms with one or two hydrogen atoms attached. The hydrogen atoms react with the oxygen atoms from the glycidol groups on the epoxy to form the cured resin. This end result is a highly crosslinked thermoset plastic, which heat will soften, but not melt - a cured epoxy. The three dimensional structure provides the cured resin excellent physical properties.

The ratio of glycidol oxygens to the amine hydrogens, considering the molecular weights and densities involved, determines the resin to hardener ratio. Changing the recommended ratio will leave either unreacted hydrogen or oxygen atoms (depending on which is in excess). The resulting resin will have lower strength as it's not full crosslinked.

Epoxy hardeners are not catalysts. Catalysts promote reactions, but do not chemically become part of the finished product. Epoxy hardeners mate to the epoxy resin, contributing greatly to the properties of the cured matrix.

That was the easy part. Now to dispel the myths. There isn't any solvent that "flashes off" out of the epoxy, unless you want it to (like thinning epoxy for penetration into raw wood) Nothing comes out that is a result of the chemical reaction and the curing process. Gases can be driven out of raw lumber or plywood if the temperature is rising during the cure, but this is not the fault of the epoxy, but the user not controlling conditions (which is the key to successful epoxy work) When epoxy is cured, there are no solvents in any pores, though there may be resin or hardener in areas, if the mix wasn't complete, again not the fault of the epoxy, but controlling the conditions. CPES is epoxy. Epoxy is CPES, they are one and the same. CPES isn't a wonder goo, just epoxy formulated to be very flexible, when compared to traditional epoxies. CPES and other epoxies don't breath. Some think CPES will breath, just like wood does, but it's a plastic and doesn't do that at all. It does remain pliable enough to move with the wood when it does breath.

On new construction and in repair or restoration work, where the piece can come off the boat, be completely coated then re-installed, CPES and epoxy can be used to an advantage. It should be noted that epoxy and CPES shouldn't be used when structures rely on joints swelling tight from moisture content changes, such as traditional lapstrake or carvel construction does. As a rule, traditional construction methods doesn't mix well with epoxy and CPES, though there are uses in these boats.

Newer construction methods, like tape and seam (stitch and glue) require epoxy. These construction techniques rely heavily on the goo's stuck -um ability and is used instead of fasteners in most cases. The great strength a filleted and taped seam can provide to a structure will allow the designer to eliminate many if not all of the traditional framing, usually found in a boat.

CPES and epoxy can greatly increase the life of a wooden boat, but there are limitations and rules that need be adhered to if success is desired. Epoxy and CPES can improve the durability of lesser quality materials, if applied correctly. The finest of materials can rot out much quicker if CPES and epoxy are applied incorrectly.

This is the end of the novel on epoxy and CPES, let the battle begin. Bring a sharp sword . . .

 

Dear Par,

I'll bring a spoon instead of the sword because I want to eat up this project.
The lesson was good and as simple as innovating E=MC2

I can see that you are deeply involved in this industry. To give you more backround on the project. I'll be building a new coastal cruiser with Ocoume marine plywood. I was planning to build it with plywood and than aplying a complete layer of thin fabric with epoxy. When I saw the post about CPES, I thought that to be on the more safe side I should first apply CPES than sand it and than do the final epoxy fabric layer. First of all do you think that this is a good idea ? or should I just go with my original idea.

The other point that you have shocked me with the words "Here it comes, wait for it . . . they are organic molecules containing two or more amine groups. Some manufactures use this little fact as a selling point to bolster it's place in the boatbuilding industry, but it's bull **** really." So are you suggesting that I can buy the cheapest possible epoxy brand for fixing marble craks and actually use it for boat building ???

Lastly, is there a way of thinning the viscosity of epoxy.

Thanks for your time
Armada

 

On projects that use modern techniques, such as stitch and glue, CPESing the materials first is a wise idea. Plank on frame or other projects that use more traditional methods, should be looked at closely to insure the structure isn't compromised, by locking down the pieces with goo and/or preventing joints or seams that require swelling, from doing so. I don't know what style of construction you are employing, so it would be a guess on my part, though most plywood construction can benefit from CPES and epoxy use.

A few manufactures try to sell their product by saying it's based on wood fiber or other organic compounds, but so are milk jugs. They tread very closely to the line of "it comes from wood, so must be the best for wood . . ." which is pure crap, once you understand the processes and chemistry involved. In short, be mindful of the advertising hype. Yes, there's some atoms and a few molecules from organic materials, but they no longer resemble the original material.

Epoxy can be formulated for a variety of needs, like filling marble cracks and bonding bolts into concrete pads, but the formulation may not be well suited for marine use, so stick with the known products. So much for saving money. Epoxy use in boat building can dramatically increase the labor and material costs on a project. It must be decided early in the project, or costs can get out of hand quickly.

Yes, you can thin epoxy. Most manufactures don't recommend their product be thinned. They also (and rightly) will tell you the cured thinned product will be weaker and void any properties shown in their testing. They don't want to be responsible (I can't blame them there) for foolish thinning practices. Thinning can be done, but I'd recommend 10% and no more then 15%, by volume. More then this and you'll loose to much crosslink and the matrix will be quite weak. I strongly advise against thinning epoxy, without a good bit of experience with the brand and epoxy use in general. You can easily screw up a batch of epoxy and will not know until you're trying to claw off a lee shore in a storm and the mast comes apart at the seams or the transom falls of the back of the boat.

The best way of decreasing the viscosity of epoxy is to warm the epoxy and/or the substrate it will be applied. This will also decrease the pot life of the mixed goo, but can dramatically increase penetration ability. Tests show additional penetration not as effective as it would seem. An unbreached coating (done at room temperature) will provide similar protection to the wood fibers then a thinned coating that has better penetration into the fibers. Basically this means, all is good, as long as the coating doesn't get broken. This is the key to epoxy permitting longer life in wooden structures and the whole point of it's use as a coating.

 

Most epoxy manufacturers offer a high and low viscosity resin as well as slow medium,and fast hardeners. I wouldn't mess with the mix.

 

Thanks for the replies.
My building technique will be lining up BS 1088 ocoume bulkheads which also at the same time forms the internal partitions, connecting them with wooden stringers and than covering the hull deck cabin etc. all of them with the same quality ply again. (No lapstrake, or swelling tech. of traditional system)
I have checked that most of the epoxy manufacturers are purchasing their raw materials from the same 2-3 factories in the world. Than they use different brand names to capture different market segments according to their price and advert policy. While eventually their basic cost is not much different from each other, the retail profit they aim is differs from 100% to 1000%.
I have found a reputable manufacturer in Europe with reasonable prices and with Lloyds approval for marine usage. The only point is that their product viscosity is 1600. Which seems very thick for me. They have thinner products but that line requires a post curing of 100 degrees C . That I cannot do as an amateur . What is your comments for the viscosity of 1600 ?
Other question is, is it safe to use stailess screws to fix the hull panels to the stringers (and burry them 2 mm into the ply from the outer skin) and than epoxy them on top. Will this be OK, so that they will not rot in the future or would you guys suggest a different system ?

 

www.oneoceankayaks.com--- Try it. It gives a rating of epoxies and their strong points.

 

Not sure what 1600 viscosity means. Any epoxy I've ever used was thin enough that for most applications it needed to be thickened. Stainless should be fine if it is encapsulated. What other types of fastenings will you be using. Just make sure they are not too far apart on the galvanic series.

 

Post cured formulations are going to be very difficult for the armature to work with. You'll be best advised to avoid them, regardless of the cost differences, it's a different formulation and not well suited to shade tree construction efforts.

It's not so much the raw materials, but the formulation that carries the brand or type of epoxy into the market. You need to focus on the goals. Your epoxy will needs should be aimed at the environment you'll be apply and using after cure. Marine use is a given so you'll want a formulation that is tolerant of higher temperatures (slow cure) in summer months, maybe an amine blush free formulation. Since I still have little idea of what your project is, I can't advise in more then general terms. This is the case with your fasteners. Sometimes you can "get away" with stainless, but sometimes you can't. Personally I don't like stainless, it hardens and breaks without little warning and it truly sucks in certain types of wood or salt water. With all this going against it, I'd rather opt for materials that have better properties like silicon bronze. Sure they cost more, but you get a more reliable product, which is generally typical.

 

Thanks for all the replies.
1- Viscosity
1600 mPas is the measurement unit of the viscosity (ie. 300 mPas thin, 1600 mPas thick)
2- Definately a very good connection to view the weathering effects
www.oneoceankayaks.com
3- Silicone Bronze
Have not been able to pin point any manufacturer under the listing of silicone bronz manufacturer in Turkey. Maybe another term is used. Could it be just bronze or brass etc. ?
4- What is blush free ?? They are all advertising about that their products are blush free !!!

 

Silicon Bronze and Naval Brass are sometimes used for the same metal in the trades. Naval Brass is a common British term and would be more common over there. Let us know if that helps you.

 

Instead of looking up manufactures of the material look up what you need, which are fasteners, you'll find many thousands of hits.

You need to get an education and some books may be in order. There are many very fine books available on the different elements of yacht construction, the materials used and the techniques employed. Most of the questions you've asked could have been absorbed in a evening's reading. Click on the "Book Store" tab at the top of the page and look at the titles and descriptions. I'm sure there will be many that strike your fancy and can serve as a handy reference as you're actually performing the tasks you need help with. The on line used book sellers have much reduced pricing and out of print stock too.

 

naval brass

Thanks. That description worked out fine. Nobody in here uses the term of silicone bronz.

 

epoxy help

Thank you for all the help. I am reading all the books that I can get hold off. But learning from other people, through their past experience it is speeding up my learning curve. And honestly in any book I feel like they are at least biased to one brand or technique. In the forum it helps to get different views and isn't the forum for that purpose anyways.
In any case, I thank to everybody for their ideas and help. When I have more questions I will call on the forums help again. And the info I receive from you is not just for me. I also translate and pass it to all my amateur boat building friends who needs the translation.

 

Amine blush

Amine blush is a film that develops on some epoxy mixes which makes bonding to the epoxy with more epoxy less effective. It also does not hold paint. It is also a ***** to sand. Go for the low or no blush!