I just had a Cherry slab planed and I want to use it for an outside bench (Michigan). Should I cover it in resin first and if so, what do I put on as a finish...sorry my question mark on my keyboard is broke :)
I'm no expert or preservatives but I'd sure think so as I don't think of cherry as particularly weather resistant. What are the legs going to be made of and will they be in direct contact with the ground? I hope you get good info and will be watching too.
the legs will be welded steel with a treated 2x4 in contact with the ground.
Like said cherry is a very poor choice outdoors.
I don't see resin saving it long enough to pay for the materials and effort involved. Indoors it's one of my favorite woods. WO, osage orange or cedar -heartwoods outside.
Add Black locust to outside uses. And it finishes real nice for benches.
(https://forestryforum.com/gallery/albums/userpics/38064/IMG_1536~3.JPG?easyrotate_cache=1607030597)
I have seen bar top epoxy for outside table last well. no great coating for wood outside applications. depends on your expectations. it will discolor and need refinished at some point. so in part it is good to use things that are easy to sand and recoat. I have used spar urethane, but have to re-do every couple years. not bad if you can just run through a planer
Locust decking is sold for the same reason. I wish I'd had time when I bought 5/4 PT pine to deck mine & saw it out of WO as I have very little locust.
Live in a log house 40+ yrs and you'll maybe learn what works best as outdoors finishes and maybe even tire of the re-do stuff. My last go round I sanded my entire home with a DA->AFTER I chemically stripped it.
A plastic finish such as above will fail once a tiny spot gets compromised. Happens much easier with wood than your vehicle which has such a finish.
would some type of oil work best for an outside finish?
it would if you are ok with occasional re-application, and sure how much UV protection you get as it soaks in, and not on the surface. maybe a coat of wax on top. I assume you question relates to appearance, and not rot resistance. since you are using cherry. there are some oil preps for log homes so maybe those guys can chime in. @Don P (https://forestryforum.com/board/index.php?action=profile;u=17) @Brad_bb (https://forestryforum.com/board/index.php?action=profile;u=6191)
I don't have any experience with a finish that would really work outdoors. I'd turn to Permachink products to try. They seem to keep the color on log homes longer. But I doubt there is a finish that will last outdoors long without need re-work at some point.
Cherry is not a wood I'd choose for outdoors. It rots very quickly, more than most woods if it cannot dry out quickly after getting wet. When I have Cherry I try to mill them first if I can so the boards or beams can dry. Bugs really like boring in Cherry too. Many bugs like cherry when it's still green, and Powder Post Beetle larvae really like it when it's dry or drying.
For outdoors, I'd choose white oak, osage, locust. For siding that will dry readily, white pine and similar can be used as well as cottonwood, Ash, etc. Black Walnut heartwood is very rot resistant, but the downside is that is loses it's color in the sun. UV will lighten it and eventually gray it out.
Spar varnish, or sikkens, but be prepared to reapply every year or two. Or, I view them as transient things outdoors and do nothing. When it hits the end of service life it goes into the fire and another one takes its place.
I left a live edge tree of heaven slab on a jobsite, we had used it as a scaffold plank. He set it on a couple of rocks by the firepit and as quickly as TOH rots that thing must have lasted 5 years before he called and wanted me to saw a set of slabs to ring the pit and for a bar table behind out of a white oak they had dropped.