dashboard varnish question

[btoran]

i am in the process of doing a custom, two piece dashboard made of mohagony and need recommendations for varnish. i was thinking about using the below varnish. it's a standard for boating projects, which require lots of uv protection. is this the best product to use or is there something else?

http://www.amazon.com/Epifanes-Clear-Va ... s=epifanes

[azruss]

I did my dash 4+ years ago with a urethane spar varnish in a rattle can. It has stood up well to the arizona heat. The last piece of wood i did, I used an automotive urethane clearcoat. This is a much more expensive way to do it because of the cost of the paint and catalyst. I have tried applying it both with a brush and LPHV spray. The spray was the best as it took much less work to get it to a high gloss. In fact, i didnt even color sand the final coat. The advantage of the auto clear coat is it dries chemically and has very high resistance to all solvents, including acetone and lacquer thinner.

[baltobernie]

I agree with Russ; automotive clear is perfect for this application. If you take your ready-to-spray pieces to your local auto body shop, they can shoot them at very little cost, as modern cars universally have clear finishes. As with Russ, you may not even have to wet sand and polish them.

[spidernut]

I did mine with urethane spar varnish in the spray can...about 10 coats, sanded and polished. It looked amazing and was very durable.

[seabeelt]

Epiphanies marine varnish six coats with sanding between
Each coat. Comes in satin or gloss

[btoran]

what grit sandpaper between coats? wet or dry sanding?

[azruss]

You will want to dry sand if your wood isnt sealed on all sides. If you have any air bubbles in the finish, you will also want to dry sand. Water on the wood will make it swell. A lot depends on how rough the wood is and how thick the clear coat. With rough and thick, you can start with 220g and finish with 400g. I would use 600g before the final coat. I found that a very thick first coat can seal all the wood imperfections. the clear coat will fisheye around those spots and you will need to sand down to the fisheye. If you expose wood before then, carefully rough up the fisheye spots with a little paper or a red scotchbrite pad. clean with a waterbased degreaser (except where wood is exposed) and wipe with a tack rag before spraying. wear vinyl gloves to keep your finger prints off the wood. It also helps to were garden gloves over the vinyl as they do not do well with sandpaper.

[btoran]

update and some questions......

first, i decided to try to finish the pieces myself with marine spar varnish, rather than take them to be clear coated. prior to staining, i prepped the wood as stated in the directions (light sanding with 220 grit and then a pre-stain to open the pores). i then applied two coats of stain to get the color i wanted. i waited a few days and then started the varnish process.

i laid down the first coat as a mixture of 50% mineral spirits and 50% varnish, then sanded between coats and used a tack cloth to remove the dust as i gradually phased out the mineral spirits. after about 5 coats it was looking nice, but i still got what i thought was dust on the surface of all the pieces. this occured with every coat i put down. not happy with the way it looked, i sanded back to plain wood and started over by re-doing the pre-stain and stain.

i then decided to take it to an auto shop and have them clear coat it. yesterday, they called to tell me it wasn't working and i went and picked up the pieces.

on some of the pieces, it looked like bubbles had formed on the surface. they said they thought this was some sort of chemical reaction where thinner (or something similar) was leaching out of the wood. they sanded those spots between coats, but where the bubbles formed there were now open pores in the wood. when they applied a second coat of clear, the same thing happened.

so, what's going on here and what can i do to eliminate it and finish these pieces nicely?

[azruss]

the problem is with the stain. They are usually oil based and thus contaminate the wood. Cabinet makers will clearcoat with lacquer or certain types of plastic clearcoat. They are not looking for an automotive finish. Automotive finished want to fish eye pretty bad with the stain. Certain stains can also lift and bubble when attacked by the clearcoat solvents. I would make sure your stain is very dry. wipe it down with a dry cloth over and over until you get nothing on the rag (paper towels are good for this). Give it several weeks to dry. Then try your clearcoat with a minimum of solvent added. With sensitive undercoats, try a light coating to act as a sealer and then build that up with light coats to get some thickness. Every time you sand the sealer coat you are exposing it to solvent reaction. Here is where a clearcoat with hardener really shines as it will be chemically dry in a day or two and give you the base you need.

[RRoller123]

Related to this discussion, (but not directly to the bubbling, which is likely solvents or moisture being released under the finish), I use spar varnish as well and after a few coats, apply furniture wax with 400 grit sandpaper, then buff. Takes care of the inevitable dust particles and makes it smooth as a baby's butt. But this is NOT a high gloss finish, more matte, which I prefer.

Pete