Thread: International Varnish.

In my experience it helps to use thinner as it will be easier to apply a nice even coat without drips and sagging (thinner coat is easier to control than a thicker one).

MIK has professionally varnished yachts, so would be able to provide superior advice.

Joost

Thanks Joost. How are things up there in the Netherlands ? I hope to get up there in the future for a holliday.
The "profi" advice I got from two different paint shops was, well, different. One guy advised to thin and the other not to but seeing as boat building here in the Schwarzwald is about as common as surfing I don't think they were speaking from experience.
I would just like to order the International thinners with the varnish if I need it.

Kev.

I believe that most brands normally advise to build up your system using lots of thinner for the first coat and hardly any for the last one. I feel that much depends as well on the circumstances:humidity and temperature. If in doubt, I always use more thinner rather than less. There are also other additives available, for example to keep the varnish flowing for longer under bad cirumstances.

That said, MIK knows a lot more about the subject matter. Or PAR if he hops by.

Still not really spring here.

Howdy,

The purpose of thinning the first coat is just to make sure it soaks into the wood fibre a little better.

It's only necessary on bare wood. Over epoxy you can go straight on with a full strength first coat. No thinners needed. The epoxy has a grip on the timber that varnish can only wish for!

MIK

(The epoxy has a grip on the timber that varnish can only wish for!)



Thanks Michael.

Kev.

MAke sure that you give the Epoxy a light sand , before the first Varnish coat , then use NO_FIL paper 320-400grit, between coats allow at least 24hours between coats .

You can if you are REALLY a perfectionist, use up to 1200grit wet&dry between coats with some water , to get that ULTRA high finish.

Remember that the surface must be DRY & FREE of any contamination.

Jeff

Thanks Jeff.

The Original varnish is for use above the waterline but I was informed that seeing as the canoe is not staying in the water for long periods that isn't an issue. Will it be OK for our canoe and paddles ? Apparently it has very good UV filters.

Kev.

Yep, varnish is fine for a dry sailed boat and the paddles too.

I disagree about using very fine papers on both epoxy and varnish. Most folks can't see sanding marks left by 280, if with the grain, certainly not 320 or higher. The surface is sanded to remove slight imperfections, but more importantly, to provide tooth so the next coating has something to grab a hold of. If you use too fine a paper, then you run the risk of the subsequent coatings not bonding well, from lack of grip on the previous layer.

I do agree in the recommendation of a No Fil type of paper. The anti clog papers use all sorts of things to get the particulates to release from the paper, often animal fats, which will quickly you off, if you try to over coat them (fish eyes from hell).

The original formulation of International Varnish has a good reputation, but is still a traditional varnish, so treat it as such. If you want really high gloss and 1,500+ grit paper use, switch to a LPU type of clear coating and you can wet sand and buff 'till you're completely over it.

Fine coats of paper are for precise smoothing operations, typically on paint, not the much heavier bodied varnishes or epoxy. Hi end paint jobs do need really fine sanding processes, but these are quite different as the material going on is much lower in viscosity and often is chemically bonded, not mechanically.

I'd agree with the sandpaper recommendation. I usually use 220 grit but the latest stuff I bought seems to clog up very quickly so I've been using 180 and I can't tell the difference. The scratches are still more than fine enough that the varnish will fill them and form a nice smooth skin. It seems to me that the smoothness of the skin comes more from the surface tension of the varnish than the smoothness of the underlying coat (to a point of course, if it feels rough to the touch then it'll still feel rough afterwards).

Thankyou once again for the advice guys. International Original it is.

" you can wet sand and buff 'till you're completely over it."

No, no, that's not me. As if the canoe isn't enough sanding, I'm sanding the floors upstairs in our house at the moment.

Kev.

Sanding is an art to a degree. I have a completely varnished project here in the yard and it needs to be a mirror finish when done, of course while still being a bright, clear finish. "Blocking" down 2 coats at a time, just to fair and smooth the surface is painful. When I'm done, it'll likely have in the neighborhood of 20+ coats, every other one smoothed out. I can apply more then 2 coats a day this time of the year, but I don't want to, as I then have to smooth them. This is an over the top type of process, but the only way to get perfect results with less then perfect substrates. The fairing process is over and it's taken about 8 coats, knowing I've likely removed 2 or 3 as I faired it. The next layers will not need as aggressive a sand regiment, but just enough to offer tooth and remove stipple. The last coat will be buffed to perfection.

When you use a true oil type varnish, do you find the process of flatting is just too laborious, both in terms of dryng time and flatting the surface? For this reason I like using varnish only where the finish doesn't matter too much. If it has to be flawless, then the easier way to go is a 2pack system. The moment it dries you can hit it with the sander. You can get an amazing finish quite quickly with a random orbit sander and a good wet/dry paper of 320 grade. For the final 2 coats use 400-600. Wet sanding means no dust and it's quite safe, provided you only use only a little water. Definitely no splashing. Wiping down with a towel as you go helps identify any high spots so you can address those before moving on. I have modified my ROS with a thick sheet of rubber which helps grip the backing of the paper. If you have slippage problems, then spray the paper backing with contact adhesive. My ROS has clips rather than velcro, which I wouldn't think will work for wet sanding.

One way of keeping the sandpaper going for longer is to have a vacuum cleaner attached to the sander as it does its work.

Completely agree with paper grade advice. I never go above 280 painting or varnishing.

I have used finer grades to repair and polish fibreglass boats ... but I can't see many applications for boats our size.

Oh .. apart from foils where 400 grit wet and dry can help make the finish quite nice.

Michael

I have a rubber cement belt sander cleaner. It's just a big hunk of rubber cement (1.5" x 6" or 38 x 152 mm), glued to a stick . I cleans debris and junk from paper very well. I also use it on just about everything else that has sand paper on it. If you use it often, it'll keep the paper cleaner, longer. Unfortunately, it seems wet sand paper has a split personality. When it's cutting, it's cutting and you can feel this, but there comes a point that it just gives up the ghost and stops cutting. No cleaning fixes this, the paper's done and it's time to replace it. Some papers are better then others, but they all seem to die before we'd like. I eat wet/dry paper like crazy, maybe it's just me, but once it stops cutting, I toss it and move to a new sheet. I've probably saved hundreds of hours in sanding time with this habit of mine, though the wet/dry paper salesman is thankful.

I can't tell you how many times I've seen someone working a dead piece of paper, just so they can finish another square meter. It takes a lot longer and the finish suffers too, if you try to "stretch" a shot piece of paper. You can feel it working, so as soon as you feel it's not, just toss it, you'll be finished in half the time, though you'll use twice as much paper.