Brightwork finish

[davidpm]

OK what is the best way to finish brightwork assuming a epoxy base varnish finish.

I've read many many posts but none answer exactly what i'm looking for.

For example:

Sand 80 , 100

Brush on neat epoxy

Sand 100, wipe with acetone

Brush on second coat

Sand 100 grit with acetone

Brush on 3rd coat

Sand 120 with acetone

Varnish using mfr's directions usually 3 coats.

I'm looking for the process details as I've head that some of the details make all the difference.

What brands have you tried and like the best.

I'm looking for a satin finish as I prefer it over the high gloss plastic look.

I'm finishing a poor grade of maghony probably meranti. It's pretty dark.

I know this is one of the most discussed subjects but I would appreciate one more pass.

[PAR]

Bright work, just like a fine paint job, is all in the prep.

100 grit sanding will show sanding marks under clear coats. Sand with the grain (very important) after you've reached 100 or 120 grit, then continue to 220 as a minimum. Many will continue up to 360 or higher.

Warm the pieces you're applying epoxy to. Just taking them out into the sunshine for a few hours, prior to applying epoxy is usually enough. The surface temperature should be around 100 to 120 degrees. Then remove from the heated area and place it in a normal room temperature area. Wait at least 5 minutes to insure the wood is cooling down, then apply unthickened epoxy. Apply as thin a coat as possible. I use a squeegee, but a roller or brush will do. A very thin, uniform coating is what you want.

This will raise the grain slightly, but it's unavoidable. The warm wood will literally suck in the epoxy, so "out gassing" shouldn't be an issue. The raised grain will leave little bumps everywhere. Knock them down with 220, again sanding with the grain. Apply more unthickened epoxy, but this time roll it on and tip off the bubbles.

Repeat the sand, roll and tip thing until satisfied, which usually requires at least three coats, possibly more depending on how smooth a surface you desire. Use denatured alcohol instead of acetone as a wipe down, prior to applying epoxy.

Now comes the varnish, which is a two stage job. The first stage is the build or bulking stage. In this stage you're looking to build up film thickness and level out the surface with longboard sanding. This can take many coats, depending on what you've started with and how smooth you desire the finish to be. A glass like finish will require many coats of varnish, with long board sessions between each coat.

Each coat will fill depressions and add to the high spots. A light go over with a fresh piece of paper on the long board will quickly remove the high spots, which eventually bring up the lows to met them. Once satisfied with the smoothness (wet sanding will reveal how smooth your work is) the second stage of varnish (or any clear coating) begins.

This stage is the actual finish, which is a sacrificial set of layers. These layers will wear or be eaten by UV in time and have to be renewed. If you don't let the finish get too bad, you'll be able to "restore" the finish coats easily. If you let the finish coats wear, so that the build coats get damaged, you'll have a lot more work to do, so maintain the coating.

The finish coats need to be applied as evenly as practical. Brushing, rolling/tipping and of course spraying all will get it done. Don't over brush the varnish, just "flow" it onto the work, push it into place evenly with a brush or roller. Let the natural, self leveling tendency of the material do it's job. You can add a "conditioner" like Penatol or similar to help the varnish "flow" and control the "wet edge". Generally, you need at least three of these coats, attempting to get it progressively prettier with each.

A show boat may have 20 coats of varnish applied, but a real nice job can be had with 6 or 7.

[Hirilonde]

Warm the pieces you're applying epoxy to. Just taking them out into the sunshine for a few hours' date=' prior to applying epoxy is usually enough. The surface temperature should be around 100 to 120 degrees. Then remove from the heated area and place it in a normal room temperature area. Wait at least 5 minutes to insure the wood is cooling down, then apply unthickened epoxy.[/quote']

Great advice!  If your wood is warming while the  epoxy cures on it you will get bubbles.  If it is cooling you will get less or none.  If you can't warm the pieces, then at least wait till late afternoon when you can be sure the temperature will be dropping.

I use 400 grit between coats of varnish after the first couple.  It isn't so much to avoid scratches, as 220 will resolve that, it is to remove less varnish.  Varnishing is way too tedious to remove any more than needed to get a good bond and/or level the wood out.

[davidpm]

What is long board sanding?

[Hirilonde]

What is long board sanding?

Not to seem the smart ass, but it is sanding with a long board.  By using a slightly flexible long sanding surface you can only sand the high spots and hence you fair out the large surfaces (like a hull) to the shape they were intended to take.  Long boards can be bought commercially or home made.  6mm and 9mm ply make good ones, I bet you have some scraps around.  Try a search in the forum on the subject, they have been discussed before.

[Ken_Potts]

   Actually longboarding might be a good subject for an article.  I'd volunteer to write it but considering how bumpy my boats are I don't feel qualified.

   I've had lots of good fairing and longboarding advice from various people around here.  Does anybody feel up for writing something?

  David - Look at Barry's post from July 7th for a description of longboarding...

http://www.messing-about.com/forums/index.php?topic=4773.0

[davidpm]

Thanks Ken, Good post. I'll make a long board from some 1/4" Okume left over.

[davidpm]

Thanks Ken, Good post. I'll make a long board from some 1/4" Okume left over.

What is the best way to attach the sandpaper to the long board. Contact cement, rubber cement?

[Charlie Jones]

I use a spray adhesive.

Here's what my shop made long boards look like by the way- they are sized to take a 3 x 21 sanding belt, cut open.

[Charlie Jones]

and while I'm at it, here's a sander I made for sanding birdsmouth spars once planed round