Tropical humidity vs okume panels and epoxy

Here maybe somebody can help me, I am in doubt again. I am in the subtropics, with average 85% rel. humidity. (32/24 Celsius)

Would the epoxy glueing be without problem in an situation with 85% humidity?

The humidity inside the new panels, they have been stored dry, and not exposed to the conditions here.

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I can borrow a moisturemeter and check, would 12% moisture be ok?

A possibility is, lay them in the sun for half a day, and cook them dry before the first impragneting layer of epoxy, would that be of any help?

I will impragnate the panels as soon as they come from the storage room

The long dry season is just starting here, than I have little better conditions.
with humidity sometimes dropping sharply mid-day. Than it´s over 32 Celsiuis

I know of proffesional painters here in Surinam working on a oil refinery, a special supervisor is running around with dewpoint/hygrometers all day. They surely don´t paint on wet days

 

If you lay them in the sun they will warp more. The best way to use them is to let them sit flat in the building or area where you will be building the boat. Let them get to the moisture level you will be at when building... a few days to a week. Epoxy will work in humid or dry... it just might take a little longer to cure.

 

If you are talking about structural work, your situation won't stop you. If you can, store the panels stickered and flat in a tin shed for a day to at least drive off some of the surface moisture, then do all laminating on a falling temperature gradient, which isn't difficult if it is 125 degrees in the shed. For small works, I hung a big tarp and had an old widow a/c running to remove moisture. It just sat on the ground and didn't cause any problems. I used tarpaper for the floor and could pull the humidity down enough to work well into the night without condensation. I also used a painters lamp to drive off condensation, but you still had to make sure the temperature was falling throughout the entire process. So if you plan to use the painters lamp, turn it on at the very beginning when the stuff all comes out of the shed at 125 degrees.

You will also have to be careful when mixing batches of epoxy and goops. They can acquire a lot of moisture during the mixing process. If you are just mixing small batches, mix in a covered cup. For instance, put a latex glove over the cup and poke a mixer through it and leave it all covered until you dump it onto the work. Excessive squeegeeing will also introduce moisture. I keep a microwave oven handy to heat the resin (part A) just a bit warmer than the air before mixing. Keep any glass fabrics in warm storage as well. Some binders in the fabrics like to suck up moisture. Talk to your suppliers about the moisture issue. In short the simple way to deal with high humidity is to raise the temperature of everything you work with until it isn't a problem. I helped build a few boats in a Quonset hut in south Florida in August. Temps hit 125 inside by 10:30 or 11:00 at the latest. It could rain all afternoon if it wanted, there were no worries there.

Also, different epoxy formulations have differing tolerances for moisture. I'll leave that for the epoxy guys.

 

I built a boat on the Atlantic coast of Panama (130" of rain per year) using WEST system epoxy with no problems. Due to the heat, I was careful to mix only small batches of epoxy and use a slow hardener, but the humidity was no problem. I was working in a covered, screened enclosure; so the wood was exposed to outdoor humidity.

 

I have been glueing with epoxy for some months now, no problem untill a few days ago.
The dry season is almost over, humidity is 50 to 60 only for a few hours a day. I have a problem now I am very worried about. I had to work in the more humid hours. (70%) The epoxy blushes grey in a few minutes after putting it on the wood. It also looks like that when it is dry. What is it? Amino blush should not happen direct after use, but hours later. in the reaction process. Because I am gleuing structural stuff, I am seriously worried about the quality of my latest work

 

I forgot to mention, I use epoxy wich should be used untill 70% humidity. LLoyd aprroved good stuff, super strong. (I think I am not the only boatbuilder who thinks that the best is not even good enough) Should I stick to humidity below 65%? Wich means I can hardly work anymore for many months.

 

Too much is not always the most suitable. I'm afraid your resin is unsuitable for your area.

I work also in a tropical humid climate. On small wood epoxy boats there is not need for highly technical resins; good elongation, no fish eye, no clogging of the sand paper -that helps!!!-, no or little blush (=no carbamate, the problem you have with your resin you'll need to wash it after curing, sanding won't be enough), excellent wetting (about 600 to 1000 centipoise mixed), easiness of adjusting the curing time are far more important that an ultimate strength.

For example the cheap resin 127 from Raka makes an excellent and durable work (I have used it since 1998). Three mixable hardeners from very fast to very slow, good resistance to UV, and very long shelf (more than 5 years) life in gallon plastic jugs in tropical climate. Never had any problem of adhesion or peeling even with pieces made during the rain season with 95% humidity.

 

Hey cool, you from Surinam! First time I ever seen anyone from there on any international forum! I have wanted to visit your country for a very long time, and Trini too. I love the chutney soca and rum

I am in the tropics and in at the start of the wet season here. I havent had any problems with the local epoxy brand. It is very humid here! Epoxy will cure in a cup of water. But is your ply is too damp then it can be a prob trapping all that moisture in there. If you have an enclosed environment and can run air conditioning then you can get rid of all the moisture in the air and it will also help dry out the ply

 

Saga, interesting idea the air conditioning for the plywood, the lone problem I see it's the eventual condensation on the wood when you take it out of the room. And air conditioning a whole shop leads to big electicity bills. I made the inverse; the fibers and woods are kept hot (100 F 40 Celsius) in a special insulated "big box" and there is a humidity trap (I do not know the name in English) with zeolithe to keep the humidity low.

It's very importance for the fibers as most -specially glass- have a very hydrophilic surface treatment and can be spoiled in a few days, that compromises the adherence of the resin on the fiber.

Woods and plywoods have no risk of rotting or damping if the humidity inside the wood is below 15%. The lone con is a theoretical loss of performance, so it's better to keep it below 12%. I treat the woods with a solution of water and mono ethylene glycol which is a very effective poison for the fungus and besides it's compatible with the epoxy. A study by the Gougeon Bros found that even improves the adherence of the epoxy.

If some blush appears on the surface, I wash it with hot water and industrial soap, rinse and sand later before the next coat or paint. Vinegar is very effective to fight eventual fish eye as it lowers the PH of the surface. In reality hot humidity is not a real nuisance (except for the fibers), as the problems are solved with little adaptation, at least we have free heat for curing the epoxy. In reality damp and cold is a more difficult and expensive problem to solve...

The important is to use an epoxy accepting humid conditions with little blush (wax like carbamates from the amines on the surface after curing). A lot of formulations of epoxies take care of this problem. After several trials in 1996-1997, I use the 127 of Raka brand (free advertisement of a satisfied customer) for its easiness of use, largely enough good performances and good price.

 

I work and store materials in a sub tropical environment too and there's no problem really. All natural materials, including plywood needs to "acclimate" to it's environment if moved form one location to another.

Epoxy can be used underwater, so though humidity can be an issue, there are formulations that work and work well, even in sub tropical environments. More so than the formulation (assuming hand laid laminates) are the procedures employed in lamination, coating and gluing operations. An acetone wash will completely dry a surface, literally leaving it sanitary. Blush will be an issue in most back yard shops, but again, good procedures will mitigate much of the problems associated with it. Lastly, don't solely rely on "non-blushing" formulations of goo. Unless you can truly control conditions and spend the money on refined formulations, blush will always be present, even if at reduced levels, because of good working practices. Simply put, if working in a small shop, without environmental controls (A/C), always assume some blush and prep surfaces accordingly.

 

PAR I do agree with you. Tropical humid climate needs simple rather cheap solutions no more, and adaptation to the local conditions like the available materials, and other small idiosyncrasies. At contrary temperate and cold climates like in Brittany -France- obliges to heat the whole shop and that's very expensive.

The problem of jhan seems to originate from the use of a high perf epoxy (Brand? formulation?) not very tolerant to humidity and blushing badly. Some resins are truly annoying with high amounts of blush generally accompanied of the pest of the fish eye and that makes the life miserable. The simpler solution is to use another resin, or learn to solve the blush problem, mainly by washing or wiping the wax like surface coat.

Another trick is to elevate the temperature as the relative humidity of air drops drastically between 30 and 40-42 degrees Celsius (see http://en.wikipedia.org/wiki/Relative_humidity). That's the purpose of the hot box for the fibers and the ridiculously expensive after importation in Mexico plywoods. With a simple "humidity tramp" using zeolithe (easily regenerated in an electric oven) I obtain relative humidity under 50% in the box while outside the relative humidity is a solid 85-90%.
Jhan could use a similar system (without the humidity tramp) simply heating a tent placed over the "freshly epoxified part" during the cure of the epoxy, getting easily a relative humidity under 70%.
A careful planing of precoating a maximum of pieces pieces like bulkheads will help also, besides it's easier to coat flat on a table than miserably trying to coat a vertical piece with the resin running and dripping and the heatied tent is smaller.
The heating must be done with electric systems (the simpler being the old style light bulbs) and never use combustion or catalysis systems as all combustions produce water, and generate pollutants and carbon monoxide.

 

Agreed it's not a very difficult issue, though the selection of epoxy formulations, to suit the build techniques and conditions, seems a simple and wise choice, if not mandatory.

 

Hey just coming back to a point someone raised about AC and condensation. I used to work in a data centre that was air conditioned. AC removes moisture from the air and there wont be any left to condense, otherwise priceless date would have rotted and millions of dollars of computing equipment sizzled. And you can use warm air while running the AC function