Varnish in Humid Conditions, the Trap Door and Using Galvanized Steel

This post includes information on the product we chose to varnish with in our humid environment, how we built a trap door for fun and function and the decision to use galvanized steel to build a walkway and lean to for the car.

Varnishing in the Tropics

With two existing wood structures on the farm we know the pain of varnishing an entire building by hand. We also have had experience with the varnishes and polyurethanes available in Costa Rica. This is why I found great joy when I noticed that the hardware stores had started selling Marine Varnish. Marine Varnish was made to be more elastic than traditional varnishes and the original intended use was for boats. Wooden boat parts are flexible and need to withstand harsh conditions including UV rays. Our wooden house will need to withstand significant daily temperature changes and a heavy rain can be followed by intense sun sometimes within the same hour.

marine varnish mineral spirit

Varnish, paint and other coatings need to be applied on dry, non-humid days. Wait about an hour after sun has come up to make sure that the dew has been dried up from the night before and stop varnishing a few hours before sundown for best results. You want your varnish to have dried to at least “touchable” before nighttime.

Our friend Caryn was a painter for almost 20 years in Florida before moving to Costa Rica. The conditions there were much like our conditions here and Caryn was more than willing to give us advice to help us get started. She recommended buying a paint sprayer and a compressor. I chose a gravity fed sprayer over a siphon type based on internet research. The siphon type generally uses a higher pressure which leaves more over spray and wastes more paint. Prices for traditional varnish here are about $55 a gallon and the Lanco marine varnish was approximately $32 a gallon so you don’t want to waste a drop. (2013 pricing).

gravity spray gunvarnish wood house

Caryn showing us how it’s done on our back wall. We started with the back wall which will be mostly unseen so we could get the hang of spraying. Keeping everything completely dust free was the biggest part of the job.

Below is an interior shot of a bedroom wall half varnished. The marine varnish leaves a shiny coating when finished. We will not have glass in our windows, only screen so we applied the same finish for both the interior and exterior walls.

varnished wood difference

Making the Trap Door

We both picked out things that we wanted in our new house, I chose a slide and Barry a trap door. Somehow, only the trap door was integrated into the floor plan. The trap door is built out of the same steel as the windows and doors using the same pattern. It can be secured from downstairs by a lock. We tried using the worn out differential we recently replaced in our car as a counter-balance but it was a bit to heavy. We needed something just a little bit lighter than the door.

rear differencial metal trap door wood house stairs trap doorWe are currently using a corteza tree trunk that was previously a planter outside. It already had a hole though it that was big enough for the rope to go through. We cut off the bark and sanded it to a shine.

Galvanized Steel

Our use of galvanized steel is minimal but most newer houses in Costa Rica are built using this as the frame and then a concrete structure is built around it. Galvanized steel pricing has dropped by quite a bit in the short time that we have been here and I am not sure why. It isn’t manufactured in CR, maybe a trade agreement with the U.S. had something to do with it.

We were going to wait until we were finished building our furniture to see what wood we had left over. The “garage” was going to be the last project. We saved three manu posts and purchased six extra roof panels but were uncertain of what we would use for the roofing timbers or reglas as they are known here. When we started to varnish we realized that we couldn’t work anywhere inside the house because it created to much dust. So we made the decision to spend the extra money and have a lean to and walkway built out of steel. This way we could both work at the same time until the varnishing is completed. It went up in a day which is one of the benefits to hiring out your projects.

metal lean to

We have a garage for the cabin we are currently living in elsewhere on the property. It is wonderful except for the times when it is raining or rainy season. There is no walkway and frequently I leave the house perfectly clean and by the time I get to the garage I am dirty. It is to small an area to justify opening and closing an umbrella. My shoes get mud on them, my notebook gets wet and my purse takes a beating.

So now I have a short walkway. We will make the concrete path later.

galvanized steel structure

* Soldering labor is generally 70-85% of your supply cost. So if you get a good deal on materials your over-all        project cost less.

* It pays to shop around. We found a $10 difference on each piece of steel. Our favorite shop couldn’t explain         the difference so we went elsewhere.

* When you hire a soldering guy make sure you look around for all possible projects. In our case, we had our         water tower reinforced with our extra material at no additional cost.

* Always paint your soldered joints. The sticks used to connect the steel will rust if you don’t use anti-corrosive     paint on them. We used black anti-corrosive paint and then covered them with chrome spray paint so it               matched.

13 comments on “Varnish in Humid Conditions, the Trap Door and Using Galvanized Steel”

  1. Casey Reply

    Sorry Newtonian, didn’t catch the part where you disagreed. 🙂

    The zinc oxide is not “quite toxic”, that’s why there are no concrete statements regarding long-term health effects. That’s my “take”, as good as yours or an old-timey welder when backed up with anecdotal evidence and unfounded opinion.

    No backyard welders, which is really all there are here outside of fabrication shops, are going to get Metal Fume Fever from welding galv unless they are purposely snorting it up, and the effects from the welding rod flux would be worse anyway.

    There are limits to everything, of course. For instance, there is absolutely no 100% safe level of X-Rays, but I assume that you still get dental and medical X-Rays or fly in jet aircraft.

    My god, quoting OSHA and its ilk in Costa Rica? LOL. Yesterday, I saw an ICE lineman using the wires he was working on to support his 30 ft. extension ladder, which sat on pavement with no one stabilizing it with fast traffic just feet away.

  2. Scott Reply

    I continue to be just amazed by the work you’re doing over there. And building isn’t really what dominates either of your backgrounds, is it? (Unless I missed something.) It’s such an awesome adventure to read about the work and to see the progress.

    • Kimberly Beck Reply

      Thank you Scott. The beauty of changing our lives and moving to Costa Rica was that we now have the time to learn new things and experiment with new projects. We are taking Green Day’s advice “I hope you have the ‘time’ of your life”.

  3. Costa Rica - International Living Reply

    I’m coming at this from a non-construction background but I loved reading your post. This is a great guide to materials to use in Costa Rica where the weather conditions are very different than most foreigners are used to. Plus, great tips on hiring folks and techniques you’re using. Thanks for sharing.

    • Kimberly Beck Reply

      Thank you. We are sharing because it would have been great to have known some of this info before we started the project.

  4. Marlene Paul & Caryn Schmitt Reply

    great progress, good picture of Caryn!!

  5. Pat Reply

    We used the Lanco Marine Varnish on the bamboo posts in our rancho a little over a year ago and it is already flaking off. Hopefully your wood is more porous and you will have better adhesion than we did.

    Congrats! It looks like you house is coming along great.

    • Kimberly Beck Reply

      Hi Pat. I read some forums that suggested that people put on 7 coats of marine varnish. I figured that our house would never be on the water (unless sea levels keep rising) so we are putting 3 coats on. After every coat we are sanding lightly so the varnish has something to adhere to. I don’t know exactly what your bamboo looks like but was it really smooth when you applied the varnish? Hopefully our house has better luck but in this environment we plan on doing some varnish work to our places every 3 years or so.

  6. Newtonian Reply

    “Soldering,” in English, is “welding” (soldering, in the USA is melting a low temperature alloy at about 800F to join electical connections or copper pipe fittings) — more specifically, in Costa Rica what they are usually doing is common stick welding. Those sticks are nothing more than a rod of steel coated with one of various compounds which, when melted by the hot arc, forms a protective slag on top of the weld to keep oxygen away from the molten metal until it solidifies. (Oxygen does bad things to welds.) The propensity to rust seemingly more than normal is becuase the extreme heat of the weld burns away all oils and contaminants, leaving behind fairly pure steel which is an ideal candidate for flash rusting. An extra problem is that the galvanizing sets up an electric current in the structure and that causes the bare steel to rust even more. Your painting is an O.K. solution but the paints here are fairly low quality and you’ll have to repaint spots on the joints every year or two. “Anti-corrosive” paint here is a joke. It’s marketing hype. Also, although it looks like you’re finished with the welding, your many readers should be aware that the smoke coming up off of a weld of galvanized steel is quite toxic. Unfortuantely, almost no welders in CR wear respirators when welding galvanized and I’m afraid that they are going to suffer badly as they age. So stay back away from the smoke when you see somebody welding on galvanized structures or “zinc” roofing.

    • Kimberly Beck Reply

      Wow, Newtonian thank you for all of that great information. Our welder did not wear a mask. In fact, I have never seen a welder here that has. Do you have a better solution for the joints? Please post if you do so everyone will know please. Again thank you for your very informative comment.

      • Newtonian Reply

        Coatings are very very complicated. I’m a materials scientist and spent a great deal of time studying and selecting which systems to use on various high humidity, offshore and subsea structures. It ain’t easy and it certainly isn’t cheap. Probably, for the average consumer, you’re on the only reasonable path you can follow. The only better solution for galvanized joints, which is “available” in Costa Rica is manufactured by Grupo Sur. They make an exceptional quality industrial coating which is loaded with a high concentration of zinc dust. This is called zinc-rich primer. If this is applied liberally to fresh welds on galvanized joints (no rust visible and no other contaminants) you will lend up with joint almost as rust resistant as the original galvanizing. However, getting your hands on that product is so difficult that I personally gave up and brought my limited supply in from readily available sources in the U.S. I’m afraid that all of us here are doomed to just keep touching up and chasing rust spots with crummy consumer paints.

    • Casey Reply

      The smoke coming off galv steel is zinc oxide. It is not particularly toxic.

      It’s the same stuff used for white paint pigment or for sunscreen. Welding on galv steel for long periods can make you feel a little ill, but it soon passes. There are no long term effects. There is no reason for the welders to wear filter masks unless they are welding it all day long.

      Most welders in CR use only 6013 welding rod aka farmer rod. It leaves a lot of slag behind that must be removed before painting or the paint will just flake off. 6011 is a better choice for a better weld and less slag but it takes a bit of practice to use it.

      I’m highly skeptical that any varnish product is going to last long when exposed to our tropical sun. Plan on recoating it every year where it’s exposed.

      • Newtonian Reply

        Well, Casey, all I can do is agree and disagree based on official health and safety documents about welding on galvanized. To quote from American Welding Society (AWS) tech document #25,

        “Zinc oxide fumes cause a flu–like illness called Metal Fume Fever. Symptoms of Metal Fume Fever include headache, fever, chills, muscle aches, thirst, nausea, vomiting, chest soreness, fatigue, gastrointestinal pain, weakness, and tiredness. The symptoms usually start several hours after exposure; the attack may last 6 to 24 hours”

        Yet, they go on to state that the “illness” will go away all by itself, given a period of time away from the fumes. There is no specific treatment except to wait for the human liver to clean out the compound causing the symptoms. Hmmmm.

        Why do U.S. health and safety organizations, NIOSH, OSHA, ACGIH and ANSI all publish specific limits or safety cautions about welding on galvanized, yet there doesn’t seem to be concrete statements about long term health effects? My take is that they don’t have enough information, BUT if it walks like a duck and quacks like a duck …

        Lastly, as a son of a welder (and he pushed me to learn, which I did) and the boss of many “old timey welders” I heard “don’t breath that smoke kid” dozens of times through my career.

        So is breathing metal fumes that cause chemical flu dangerous over the longer term? I guess I’m not enough of a medical professional to give a conclusive answer. As for me and anybody that did or ever will ask my opinion about welding, I’ll continute to strongly discourage inhalation of any metal fume or oxide — I even discourage breathing the smoke from any weld process. Smoke is bad.

        Nobody is telling Costa Rican welders this (as far as I know) and I think it’s a sad state of affairs.

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