At 11:44 AM 4/16/04 -0700, Howard Battan wrote:
>"I will be replacing the floorboards in my '57 MGA. What have you found to be a good paint or treatment for them to make them hold up well?"

Penta wood preservative is good (or maybe any equivalent). Brush on and let dry. Especially try to fill the edge grain, over and over and over. Do several coats (over several days maybe) until it won't take any more and starts to look a little glossy. Allow to dry, and paint with a couple coats of black enamel.

Addendum, September 5, 2009:   Well that's interesting. I just found out that pentachlorophenol (the active ingredient in Penta Wood Preservative) has been restricted since 1984, and is no longer available to the general public (although still used in industrial applications for utility poles, railroad ties, and wharf pilings). They say it extends life of telephone poles from 7 years to 35 years. No wonder my floorboards are still like new after 23 years on the road. The EPA restricted its use on the basis of it being "possibly carcinogenic to humans" with anecdotal evidence only with normal exposures.
See here: https://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=70

I guess you will have to ask your "helpful hardware man" for a recommendation for a modern wood preservative. For what it's worth, linseed oil does a nice job of sealing wood to keep moisture out.

Addendum, November 27, 2009:   Another web visitor recently recommended using Black Sote by Alcatraz. See here:
https://www.sampsoncoatings.com/183200group.htm
www.sampsoncoatings.com/Datasheets/PDS Sampson 183200.pdf
www.sampsoncoatings.com/Datasheets/MSDS Sampson 183200.pdf

It looks like Asphalt with about 50% solvent solution. I have no idea if there are any anti-fungal chemicals included. Definitely not Creosote, but apparently the modern "safer" substitute for consumer use. It should be okay for floorboards, but I think I'd treat it more like a soak-in stain and paint over it as well.

Addendum, January 3, 2011:   This recommendation comes from Bill Wardlow at The Motorway Ltd in Fort Collins, Colorado.

"In our shop, we've been protecting wood with a two part epoxy mixture that's extremely thin and watery when mixed. It penetrates the wood like a champ, and then hardens, having permeated the cellulose fibers. The wood is 'forever' converted and protected from rot. We use NOTHING else, except for a coat of paint, or soundproofing if needed. The stuff is called Clear Penetrating Epoxy Sealer. It's manufactured by Smith & Company (really!). We get it from a local specialty hardwood and fancy carpentry place. It says on the can that it's made in Richmond, California. It is nasty stuff when not cured. Use a respirator rated for organic compounds and such. (It tells you on the box). Work in a WELL ventilated area, preferably outside, and avoid prolonged exposure. Really, we haven't found it objectionable at all in working with it. Just follow the directions. On the box it says "cold weather formula". I don't know if that means it comes in different mixes or not. You may want to ask. We think the stuff is great".

Addendum, August 6, 2012:   This recommendation comes from Steve Miller.
" On the floor boards, I think I will try to use Sikkens deck treatment, which is like a transparent water repellant, but after a couple coats becomes thick and shiny. We have used it on decks, barn walls, fence posts and more in the past, and in weather, it will last for years....have seen no signs of deterioration over at least five years. Sikkens recommends a re-coat in full weather every year or so, but we have never done so on many apps. I think this will protect the wood well. Hope it can withstand the exhaust heat (will use some type of heat shielding)".