I'm planning on building a PU bed for my '25 runabout. I will be using it for bringing home various treasures found during some of our many "excursions". I am using white ash and I don't need a "Show Quality" finish, just something decent and fairly durable. I'm thinking about marine spar varnish but wonder if that will be too easily scuffed. Also considering just some type of oil finish. Decisions decisions.
The pickup in my profile has red oak. I used boiled linseed oil. It's good, but, lots of work. Like my mentor told me--apply once a day for a week, once a week for a month, once a month for a year, then annually thereafter. If you don't, it starts to dry out. My TT (on the PHOTO link of MTFCA home page)has cypress wood with a half dozen coats of marine spar varnish. One coat a day and sand between coats. Starting to get tired where the sun hits it--been there since 99. Used spar varnish on my Hack in 2010. Only used 2-3 coats. Where it lives in the barn the sun hits it most days. It's getting tired already.
CONCLUSION: IMHO, I'd use my favorite stain, then do 6-8 coats (top, bottom, sides, and ends) of marine spar varnish, and don't park it daily in the sun. Or, paint it black!
I've had a little experience with wood finishes used outside (although mostly on boats).
My rule of thumb is this: If the wood will spend a majority of its time outdoors and not in a garage (or covered boat slip), I have always preferred an oil finish. Mostly because ANY kind of varnish will crack and blister with the sun and its the removal of the old finish (not the applying of a new coat) that is so work intensive.
If the wood will spend a large proportion of its time indoors (garage), it will take a looong time for cracking and blistering to occur, so a varnish like polyurethane can be a good choice.
My 16 ft. cedar strip planked boat was done with polyurethane varnish about 5 years ago and still looks good, but it only goes out 12 or 15 times a year for maybe 6 hours each time.
Then again if you enjoy scraping and sanding old coats of varnish off ..... anything goes. ;o)
You may like to consider the clear used on modern cars. Virtually all the colors on vehicles today are finally coated with a 2 part clear Urethane Enamel (Buds Polyurethane is similar)
It is designed to be able to withstand all the types of weather and all conditions an owner may subject it to even left out in the open all the time.
Sand and prepare as you would for any varnish/paint apply it in an over thin coat first to get it to soak in. then 2 or 3 coats. You can spray or brush but you need to wear a mask if spraying. Because it has hardener it will set to a rock hard surface in a short time varnishes dry slower and often extended time is needed before it is hard enough to sand if you need to.
Timber is always a problem as it itself expands and contracts with weather/temperature so you will never have surface as good as solid ones no matter the finish.
A Model T garaged and used normally will probably never need to be touched again. The wheel spokes on one of my cars is natural wood its been 17 years and they are as good as new.
If you want it to be authentic, paint it. Model T's with pickup beds were meant for work, not for pretty. Green, gray, and black were the most common colors.
I built a Huckster several years ago. I used Spar Varnish for it. Do not use polyurethane unless it is not going out into the sun, as there is little to no UV protection. I did the first coat as a very thin soaker coat. Light sand and then a second thin coat. Then 2 more spray coats. I varnished each board as a separate piece. Then after it was assembled I scuffed it and did one final spray coat. I could wash it at the car wash and it was still looking good about 10 years later when I sold it. I also stained it a English Oak color. That way I could use Old English scratch remover to maintain the new look with ...
You can brush on two coats of Minwax polyurethane spar varnish. It will look better than a temporary linseed oil finish and last for decades.
I used Helmsman spar varnish exterior, completely assemble bed. when you are satisfied with out come take it all apart finish all sides and ends. Three coats sanding between with 220 grit. when cured apply several coats of good wax. A lot of fooling around but it will produce a durable nice looking finish.
Royce & William - I used this same varnish to refinish the oak on my depot hack which had become somewhat "weathered". And I have to say, it worked GREAT! As I recall, if you wait about an hour, you can apply an additional coat, and you can do this several times,....as needed. I got some advice from a local woodworking shop here in town, and they actually advised that a couple more than two coats would be a good idea, so I put on four coats,....mostly because it's so easy!
Anyway, for anyone who want's to try it, I think that between you two guys (Royce & William) you almost got the name right. (....or, at least the name of what I used,......) which was Minwax Helmsman Spar Varnish which is a urethane,.....FWIW,......harold
Mike, I was thinking the same thing. I don't mean to offend anyone, but I believe there were few natural finished wooden bodies back in the day.
Hal -- I don't mean to offend anyone either, but I (we) probably did.
Back in the day there were probably many with a totally "natural" finish--no paint or varnish. My grandfather occasionally brushed burnt motor oil on his homemade truck bed to "turn the water".
I used to know a fellow in this neck of the woods who had a sawmill. He used a mixture of used motor oil and diesel fuel for just about anything -- from truck bed water repellent to mange treatment on his dogs. And it worked pretty well for all of it.
I used Helmsman spar varnish on the wheel spokes in 2010 and it still looks good so I think I shall stay with that. If it scuffs up too bad on the floor of the bed I can always apply a few more coats.
Mike W, I used old engine oil on the '53 Chevy PU I had about 20 years ago and it did keep both the water and the mange away, at least for the 5 years I had the truck until my (now former) wife sold it one day while I was at work.
I have a friend who is a professional restorer. He really does his homework and goes the extra mile to make sure his jobs are truly like they left the factory. He had a customer who brought him a 40's or 50's pick-up. The bed, of course, had wooden boards in the floor with metal strips between that held them in. The customer brought over the wood to go in the bed. My friend installed it all and painted it body color. When the customer came in next time to see how things were going, he dang near dies of a heart attack when he saw his beautiful wood had been painted. The fact of the matter is, the wood was painted at the factory and this guy would loose points if it were any other way. Once my buddy explained it all to him, he was OK with it, but I think he was still disappointed to find out what the truth really was. He had truly believed the factory finished that wood in a natural finish with body colored metal retaining strips. And why wouldn't he? When was the last time you went to a car show and saw one that wasn't?
In my area the farmers used to spray their wood shake barn roofs with the motor oil from their farm equipment and cars. Worked great at sealing the roof and preventing cracks and splits but when one of those barns caught fire you could see the thick black smoke for a 100 miles!
Last year, I refloored my 16'open trailer. To keep the wood from rotting out so soon, since it is kept outdoors, I used Varathane Helmsman marine spar polyurethane. Six months later, it still looks like the day that I finished it.
As usual, I'm with Mike. Look at period photos of old cars; you rarely see any non-painted wood showing. When I was doing research for our '23 Roadster, I noted that many of the T era trucks and pickups were painted in colors other than black. Of course, the black and white photos don't show which colors, but they sure aren't black. Apparently, business owners wanted they're vehicles to be noticed.
I chose Dupont Nason for our project and had a friend hand paint my grandfather's name on the side of the box. I was going for the look that the car might have had if he had continued his father's blacksmith shop.
Looking through old pictures this morning I found these and thought of this discussion. I think these show that weather will eventually get to just about any paint or varnish.
I used marine spar polyurethane on this backyard swing. Notice how the vertical surfaces have survived better than the areas where moisture could sit.
I covered the enamel on this mailbox sign with three coats of marine spar polyurethane, which is why it has the yellowish color instead of white. Even the vertical surface is peeling.
If I had waxed the swing and the sign regularly I'm sure they'd be in better shape, but the bottom line is that whatever finish you use is vulnerable to enough outdoors exposure.
Linseed oil is a great finish for furniture or anything that is kept indoors, away from rain or sunshine.
Polyurethane spar varnish (I like Minwax Helmsman brand) is the way to go for long lasting maintenance free protection of wood and great appearance for anything that is exposed to sunlight or moisture.
Here's a recently Stutzmann respoked wheel I brushed with Minwax last weekend.