Just an FYI: wood truck beds from the factory were painted body color not black unless of course the truck was black. This was the case for 53 and up trucks so I am assuming it wasa this way for 52 and down trucks.

If I ever redo my truck I am painting my boards body color.

 

I was thinking that if you want a smooth coat you need to sand down your last heavy coat and add a few coats of sprayed varnish... It's one of the few ways your going to get a smooth surface with varnish... I think your varnish looks great as it is... and as it's used it will knock down the high spots...

 

Personally I wouldn't worry about it unless you are going to keep it in a climate controlled room and never expose it to sun or rain. Any film coating like varnish on wood is gong to crack, check, and lift within a year, and the wood is going to turn grey/black where exposed, especially oak. It's the nature of the beast, Varnish or other surface films cannot expand and contract as much as the wood, applying it at a lower temp than the average outdoor exposure only speeds the film failure and will need to be stripped and redone about yearly.

 

AX, It is troublesome but is not quite as bad as you indicate. I spread a lot of varnish each year but rarely have to strip it. I restored and maintained a 38 Ford Woodie for a number of years as well as the boats. Ford used Maple but GM used Oak on the Woodies. The oily woods such as teak are the most difficult. I gave up trying to maintain varnish on horizontal teak.
Horizontal surfaces such as the bed wood are the most challenging for the obvious reason of more UV exposure. UV is the enemy of varnish. If you cut down the UV exposure (a garaged truck when not being used) and you regularly sand and recoat ( I do 2 maintenance coats each year on the boats) you can maintain varnish and prevent the need to regularly strip. A couple of essential steps to do is to seal the end grain of the bed wood thoroughly, particularly if the wood is red vs. white oak and the initial coats should be thinned per the manufacturers directions. Red oak is quite porous compared to white. My test is if you can suck on the end grain and it acts like a straw it is red oak.

 

Talk about porous, a fella once told me you could blow bubbles with a red oak stick.Didn't believe him till I did it myself. 1/4 by 1/4 16 inches long in a cup of water. Sealing the endgrain is definatly a good thing.

 

Bill, how long it takes before needing to strip and recoat depends on several factors:

Wood species: as said, the more porous the grain the worse it will be. If you must film coat an oily wood (or even glue it) give it a liberal washing with acetone just before varnishing. Varnish or glue as soon as the acetone odor dissipates.

Maintenance: as you indicate you must reseal any microscopic crazing before moisture can penetrate to the wood. This is a lot of work to do a couple times a year especially since the wood will need to be removed in order to reach all surfaces.

Quality of the seal: ALL surfaces must be sealed completely. This is difficult to achieve especially n end grain and in drilled holes or routered grooves. As soon as you tighten down the bolts or metal bed strips you almost definitely will break the film seal. End grain is especially difficult to seal, sometimes necessitating dipping and/or soaking the ends of boards in thinned finish for a period of time.

Reactiveness of the wood species: some wood species expand and contract, warp and twist a lot more than others. Most of our domestic hard and soft woods are highly reactive due to seasonal climate changes and soil moisture content when growing affecting winter and summer growth rates. Reactive woods will cause any applied film finish to break. less reactive woods (hard maple, birch, etc) have a tight even grain and color that most people find less attractive.

Climate changes that the finished wood is exposed to: The more extreme the temperature swings and humidity changes you expose the truck to the shorter the life of the finish. Look at the exposed wood in the Atlantic or Pacific North for how quickly wood deteriorates when exposed to large climate swings.

IMHO maintaining film finished wood exposed to the environment is a labor of love and major time commitment. There is a reason there are few woodies left that haven't had all the wood replaced. Boats spend more time under covers and in constant humidity than exposed to the sun and/or are constantly being maintained, most wooden boat owners spend much more time maintaining it that riding in it. If you like regular sanding and finish reapplication a couple times a year or more, and plan to never actually put anything in the bed, more power to you.

 

The results for coat eight are in. It looks 100% better, the wife even thinks it looks good and the bumps are pretty much gone. I will probably put on one or two more coats before installing in the truck but at least now I know that my application is headed in the right direction. I am thinking that filtering the varnish, turning off the shop heater and just getting out of the shop so that I didn't make any dust helped the most. But I am just guessing their.

When I looked at the results of my test board the finish done with the foam brush was a little better than with the china bristle brush. I am using Jen foam brushes, they are a little better quality. I am not saying that everyone will get the same results but I think that I will stick with the foam. As far as final coating with thinned verse full strength, there was no comparison the full strength produced a much better finish.

topmoo If you still have the bumps then I would suggest that you skip the rinsing with water. The varnish dust that is left after sanding will blend right back into wet varnish anyway - it doesn't have to be removed. If I was doing it I would blow off with air and lightly wipe with a lint free cloth or a tack cloth but not use any water. If you were to look at your 8 coats of varnish under a microscope you would see a surface that looks like a sponge. Even though the holes are very small they are enough to hold minute amounts of the water you are using to wipe the dust. They won't dry easily so I think the bumps you are getting is from them gassing and causing the next coat of varnish to bump up.

I have always read that the finish coats should be wet sanded, that what Epifaines recommends. Are you saying not to use water in the wet sanding process, maybe mineral spirits or just to dry sand or just not rinse with water after sanding?

Ax The truck is kept in a heated and air conditioned shop and I live in AZ were moisture is really not a problem, I am hoping to get more than a year out of the wood finish.

 

Dry sanding with most finishes will simply load the grit with swarf and causes poor results. Others will have differing opinions. If cutting dry, oil-free steel wool (wash with acetone to remove oil) or "Scotch-Brite" pads won't load up like abrasive-coated paper.

 

When I use varnish and I need to wet sand I use VM&P Naptha with stearated paper (usually light grey or the black wet/dry). The naptha drys quickly and won't react with the varnish to cause gas which makes the bubbles.
Epifaines may know something that I don't since they are the manufacturer, but I have refinished several woodies including the one I built and haven't had a problem with bubbles doing it like I outlined. There are always several ways to do anything

 

That sounds like a lot better way of doing the wet sanding then what I have been doing with water. So after sanding with the VM&P Naptha you just wipe it down, tack and recoat? That almost sounds to easy.

 

It has always worked well for me. And yes, after the naptha drys wipe it down with a lint free or tack cloth and re-coat. It is pretty easy to wipe because it leaves a very seeable film that is the stearates and the dust combined. And you will find that sanding with the naptha really makes it smooth.
Have a great holiday!
EDIT: BTW, make sure that your varnish is really dry and test a small area (or a separate sample made at the same time) first to make sure that the naptha doesn't melt the varnish.

 

The floor is finally in. The last coats of varnish went just fine. I quit wet sanding with water and used VM&P Naptha as a lubricant per Topmoo's suggestion and what a difference it made. The bubbles and bumps are now completely gone and the finish looks great. Thanks everyone for your help.

 

That bed looks great! Nice work!

 

That looks great. The extra effort was definitely worth it.

 

I put 6 coats of urethane spar varnish, block sanded each coat smooth and sprayed the last coat. It has been three years and still looks like it did when finished. I keep it in a closed shop and try not to have any rain on it. There has been two pretty heavy rains but it did not seem to hurt the finish. Like ax said there is no way to keep time from causing wood finish to crack or split. <a href="http://s247.photobucket.com/user/Larry48fi/media/100_0663_zps47b868b4.jpg.html" target="_blank"><img src="http://i247.photobucket.com/albums/gg131/Larry48fi/100_0663_zps47b868b4.jpg" border="0" alt=" photo 100_0663_zps47b868b4.jpg"/></a>