I would not say that all failed (I have not recently checked to see if they still show all results from all tests they have done over many years).
I used the technique that Mar-K considered to be best - follow the material/paint instructions very carefully.
- two to three coats of POR (with careful following of "repaint" time)
- two coats of high quality exterior house paint
Unless it gets heavily scratched - it does not fail.
Coat all 6 sides of each board.
It is tedious and awkward - but it has worked well for me.
It is on the 21' bed boards on my 54/55 GMC 350 COE flat-bed.
Painted about 6 years ago.
The bed sits uncovered for 8 months of the year - in upstate NY.
Here is a post in an old thread. Mar-K's links do not work - they have changed ownership and most likely have have changed links/webpage?
