I am having some difficulty getting a bubble free application of epoxy. I glassed and then added a second and third coat of epoxy to the seat for my Triad.
I used fast hardener the first time and got lots of bubbles. Some were as large as a pencil eraser. I put that down to shop temperature possibly rising while it cured as the sun even in winter can add a few degrees to my shop in the day. I heat the shop with a wood stove and wait to see a drop in temperature after a few hours of heating. That usually indicates the wood is burning down and so a cooling trend will occur in the shop. However it was afternoon and so a bright sun may have reversed that trend?
I used slow hardener the second time. I waited until the cooling trend set in and applied the layer of epoxy. It was night so solar heating was not a factor. Again I got bubbles. Much smaller but still several of them?
This is not critical as I intend to sand and paint the seat with non skid paint so smoothness will not be a factor when finished. I am concerned though as on other areas smoothness will be a factor and of course bright work would be very noticeable.
The seat is made for poplar. It is about 3/4" X 4 1/2' X 11". Poplar isn't great boat building wood but I thought for the seat it might suffice. The epoxy I am using is called Marine epoxy. I bought it from Duckworks. It works very well for gluing and I didn't notice bubbles during the glassing of the seat or the other smaller pieces I glassed.
I am considering ordering some different epoxy and using the marine epoxy I currently have for the gluing with fillers added. On that note I am looking at either West Systems 105 with their 206 slow hardener (I like the extra time when applying) or MAS epoxy. The MAS people claim theirs is amine blush free? If any of you have used West or MAS or have favorites in the epoxy realm please share them.
Out gassing is a common problem, which you have an understanding of. Wood holds its temperature quite well and will remain in static state for some time after a temperature change.
When I do small pieces in cold weather, I take the pieces inside the house or use a heater and intentionally raise the temperature (over several hours) then return them to the much cooler area. I let them sit in this cooler area for at least an hour so I can be sure the internal wood temperature is descending. Of course, thicker and larger pieces need more time.
If still having issues with bubbles, it's very possible you're putting them in as you mix and/or apply the epoxy (very easy to do). In this case pull out the butane torch (I use MAPP gas), light it and wave it over the surface of the work. The bubbles will pop and lay down. This is an old trick and works well. The epoxy manufactures will have you use a heat gun, but the torch works much better. Don't linger, keep it moving (trust me), then stand back and wait for more bubbles to appear. Don't let the flame touch the work as the pressure of the gas coming out will literally move the wet goo, possibly leaving uneven areas, just glide it over the surface, just above the work.
I use propane when making epoxy coated countertops. The instructions call for it. They say it's not the heat that pops the bubbles but the carbon dioxide. You can get the same results with this product by an open mouth breath on the epoxy. I found out that you'll pass out long before you get a big bar top done though, and if you land forward you'll have a lot more work to do sanding your face out of the epoxy. The torch works much better. I never had a problem with bubbles while building the boat, so I can't how well it would work, but if Paul says it works you can pretty much count on it.
Good luck
Keith
I have already moved the small propane torch to the shop. I will give it a try on my next epoxy endeavor. Now any ideas, preferences or WAGs on West, MAS or other epoxy favorites for my next epoxy order? I will continue to use my marine epoxy until it is used up but will order a gallon of MAS or West in the next week or so. Nothing against my current epoxy, I just want to try a different one and compare.
Since I currently have 2 additional sets of plans, the original Weekender and original Skipjack, I am sure I will find uses for any extra epoxy. I am not sure what my second boat will be as there are 2 John Welsford and 2 Devlin boats I really like. I want to try a stitch and glue construction so may choose one of Devlin's designs as he seems to prefer that method.
I have used West as well as others, they all seem to work fine if mixed properly. On larger ply areas of boats I apply it over cloth with a 3-5 inch "putty" knife rather then rollers and that seems to work the bubbles out as you go. These days I try to not use epoxy for several reasons, but others swear by it. My last two boats were "epoxy free" and I must say, far more enjoyable to build (for me).
I've used west and it is a good product but I think it's way overpriced. I've heard a lot of good things about MAS but never used it myself. My boat was made with Raka epoxy which you can get a discount if you're a BYYB member. It worked just fine for me and the cost was much lower than most other brands.
Keith
From a technical stand point, all the major brands have very similar physical properties.
Raka seems less viscous then others, but this can cause you to use more to fill weave. Both West System and System Three are very close, though System Three is pushing filler included resins which can speed up work for some, though isn't the most cost effective way to get thickened epoxy. I've limited experience with MAS, but the little I've used it, performance was good.
My back ground was in chemical and structural engineering in collage, so I look at things differently then most.
I've been using a proprietary mixture for several years now, to suit my tropical building environment. My super slow is about 20% slower then West 209, but is much more "reactive" to those that are sensitive to epoxy (it also will blush like no bodies business). A friend builder that stopped by the shop, saw my newly delivered gallon cans of the super goo and turned pale white and instantly left. The can wasn't open, but his sensitivity to this particular brand is very high.
I've tested most of the major brands and West has slightly better performance across most categories, though the margins are slim. Not much compares when you can get a custom formulation like I have. It's designed for my needs and has the physical properties I desire.
Epoxy can be formulated to be flexible or brittle, permit higher or lesser moisture vapor to penetrate, plus a host of other variables.
For the average builder all the major brands will suffice. Find one you like and learn it's quirks. Each brand and hardener will act slightly different under the conditions you work. It takes time with a product to figure out what it wants for consistent results.
Epoxy use is basically procedures and following them to the letter. Once you get a handle on this, epoxy work is relatively easy.
Paul, Thanks again for the in depth information! Do we get an associates degree in chemical engineering if we read all your posts and can pass a test on their content? (Please take that with the humor and appreciation I intend).
I am basically switching from the "marine epoxy", (the actual name they sell it as at Duckworks), to a name brand so that future uses and purchases will be a consistent mix. I suspect they buy whatever is the cheapest and bottle it in their "marine epoxy". They advertise it as economy epoxy so I am not complaining about their method.
My attitude towards cost, in boat building, is changing. I originally was very concerned about cost and still am to some extent but after factoring in the hours spent building and the desire to have a nicely built boat when finished I am not as concerned about the cost of the epoxy.
I also find the idea of building a boat without epoxy very interesting. I think I would consider it if I weren't using plywood. More specifically thin plywood. Some time when I am more awake I might do some math and see which weighs more, a boat with each plywood layer thicker or a boat with a layer of epoxy and glass cloth? Most of my sailing will be in lakes or reservoirs around Montana. They tend to lose a lot of water over the season so the possibility of scrapping the hull is really more of a reality. I am hoping the epoxy and glass cloth will add a bit of defense in that area.
I didn't take any engineering courses in college (my expertise is the 19th century Civil War and antebellum experience), but I only use West System epoxy. I generally use the slow hardener because I like to have time to work and it is almost always too warm here...unless it is too cold (Vegas has two seasons, one short cold one and one very long HOT one) I try to buy it on sale but I find the cost is worth it no matter what because I have never had a bad layup with West nor have I experienced any failures with it. Jamestown Distributors sells it and I believe we get a discount there too.
my 2cents
a.
The epoxy Chuck sells at DuckWorks is real marine epoxy and rebadged just like many epoxies (especially CPES products, which I don't bother with any more) The DuckWorks stuff is fine and a name brand.
I have the same problem Adla has, with a nice season where I can use normal to slow goo and 9 months of, you better have the slowest stuff available or your screwed season. BYYB members do get a discount from Jamestown Distributors so this can mitigate the costs of West System a degree.
I'm moving away from epoxy as much as I can. I've found it has been over used and over rated in recent years. If you're interested in some none or minimum epoxy designs drop me an email and tell me what you're needs are in a boat.
Terry, you can get a degree of sorts if you can properly pronounce the standard epoxy molecule (diglycidol ester of bisphenyl A) and tell me what the A stands for.