Varnishing Agony

[cruiser_pete]

Yesterday I decided to repair the varnish on a small section of toerail. There are currently 10 coats of Epifanes that were applied a few months ago. A small section was damaged when a launch driver put a line on one of my mid-ship cleats and backed down hard. The varnish was damaged in a small section.

I taped off a 12-inch section of the toerail, sanded with 220 then 320 grit. After cleaning, I applied a coat of Epifanes Wood Finish Gloss. About 8 hours later, it was dry to the touch and looked great. I then applied a second coat and went home.

Went back to the boat this morning and the finish is totally dull, no gloss at all.

It was somewhat humid last night.

Is this a result of humidity? Did I put the second coat on too soon?

What now - do I need to sand off the coats that I put on and start over?

Thanks!

[Cheechako]

likely a result of the dew settling on the finish after you left. light sand and recoat earlier in the day....

[cruiser_pete]

Originally Posted by Cheechako

likely a result of the dew settling on the finish after you left. light sand and recoat earlier in the day....

Thanks Cheecako.
I hope you are right, as this is exactly what I did. I wasn't sure, it was just a guess.

[Roy M]

Never brush after 1 PM. Spend the afternoons sanding and prepping for an early start. Same with LPU. When you have more experience, then you can start bending rules, but by then you'll be taking responsibility a bit better if things don't work out.

[Crimea Cruiser]

'Wait for period of lower humidity as in autumn. Wettest June on record in NJ. over 10".

[Roy M]

If that's the case, send the boat to Seattle where they know how to varnish in less than ideal conditions.

[cruiser_pete]

This is exactly the issue.
I have to make the repair. I don't want to leave the wood unprotected. So, I need to make the best possible repair in the conditions.

[Roy M]

If the repair is relatively small, sand the area, clean it of dust, dip a lint-free rag (a diaper is best) directly into the can of varnish, soak up a little, then rub the varnish into the repaired section. Rub hard, since you are now abrading the substrate and sealing the outermost layer of the substrate. Keep rubbing until the area is beyond tacky and almost dry. Then repeat after enough time for the repair to harden. This is called "French polishing". It works for interior and exterior work. It doesn't put on the thickness of varnish finish that brushing would do, but it is slow and sure, and you can often do it between squalls. Even if it gets wet or dull, the next application, when rubbed hard enough, acts to burnish the substrate and make for an eventual brilliant repair. Don't expect to cover a lot of area in one work period, but you will eventually be able to make a beautiful varnish repair. Later, when conditions are better, you can begin applying thicker coats by brush (and appropriate amounts of thinner).

[cruiser_pete]

Roy - Thanks. I had not heard of this approach. I will definitely make use of this.

When you say "sand the area" are you referring to a light sanding to the existing finish, or a full sanding starting with a coarse grit all the way to the wood?

I opted for the first approach as I didn't want to take off the 10 coats that were just put on a couple of months ago for a repair that was just a couple of square inches.

Was this the right approach?

[Roy M]

Since you are going to be working on this project for a while, and you want it to last for a longer while, spare no effort to make the substrate perfect. That can mean stripping old varnish with a chemical stripper, or using several cans of elbow grease and a bunch of sandpaper. Then, if the substrate is stained, use a two-part teak cleaner or single part oxalic acid solution to bleach it to a uniform color. Give it a light sand with 120 grit and wipe it off with alcohol or thinner. If you have the time to get it on, put a coat of well-thinned varnish on with a brush to seal the wood. Sand the "cheap haircut" of wood fibers that fill with varnish and stand up, and wipe it down again. Then build with thinned coats of brushed varnish when the weather is forgiving, or rub it down with the varnished wet diaper to get ahead a little more in inclement weather. If you are brushing, sand with 120 at first, until there is some real filling of the "valleys" and lopping off of the "hills". This will ensure a super shiny finish that tells folks you know how to do this awful task. Later, start using 220 grit, since all you need is to provide some "tooth" for the next varnish coat. For French polishing, you don't need to sand, since the diaper acts as a fine abrasive, spreading the "lubricant" of varnish and burnishing it dry. That's for a complete, down to the base, treatment. If you are just repairing, play it by ear, polishing when it is damp, brushing the repaired areas when it's warmer. You want the repaired area to be filled by the same thickness of final finish as everything else.

Then it's time to start all over. Ah, the joys of varnish......

[cruiser_pete]

Got on the boat today, and the light sand and new coat of varnish that I put on yesterday looked good. Thanks for all the help.

[minaret]

Originally Posted by Roy M

If that's the case, send the boat to Seattle where they know how to varnish in less than ideal conditions.

Seattle tip-use Japan Drier with a traditional varnish like this. Plus everything already said. Careful accelerating if its hot out, but you shouldn't be coating if that's the case anyhow.