I have always put 2 coats of polyurethane on the bottoms/backs of cabinets and furniture, parts that are never seen, just to seal up the wood. My question, is 2 coats really required just to seal up the wood?
I have always put 2 coats of polyurethane on the bottoms/backs of cabinets and furniture, parts that are never seen, just to seal up the wood. My question, is 2 coats really required just to seal up the wood?
For no-show surfaces I want to protect or where I want to mitigate moisture effects I use a 1lb cut of shellac. It goes on easily, adds a bit of warmth color-wise and leaves a smooth surface when sanded to 400. I generally leave drawer boxes unfinished but, if the function calls for a sealer I also use shellac there.
"A hen is only an egg's way of making another egg".
– Samuel Butler
If you truly want to seal the wood you need to put on enough finish to create a contiguous film. I've never found that necessary on stuff I can't see. Most of the time I don't put anything on stuff that can't be seen. When I do, like Glenn, I use shellac, but only a single sprayed coat of Sealcoat. It provides some protection but it's definitely not going to seal it.
John
For something like a back, one coat (or no coats) is enough.
I never finish the backs of furniture that won’t be seen. It won’t make a bit of difference re: movement.
I built a cabinet a few years ago that was intended to go up against a wall, so I thought I'd save some work by using a plain back with minimal finish. A year later we moved and in the new place the cabinet worked perfectly backed up to a settee in the living room, which of course exposed my plain, unfinished back. I then had to retrofit a fake finished back for the cabinet, way more work than just doing it right in the first place would have been.
No more, everything gets a back now that will be OK if it ends up being exposed. I've learned my lesson about stuff that "will never be seen".
thanks - I agree the extra work could be frustrating if you change the location of the piece. So far all the furniture I built would happen to have the same problem you had after moving the piece. In this case, it's a bath vanity and will never move from it's location unless someone decides to remodel the bath in the future.
I think you're safe with a bathroom vanity! Cabinets like that I use prefinished maple ply for the boxes, if it comes finished both sides the back is finished, if it's one side finished material it goes unfinished. If I were finishing the boxes myself I'd apply finish on all sides, not for any great reason.
I wouldn't typically apply a finish to the back of a built-in cabinet...I kinda take the same track as Roger just mentioned. And if a future owner removes that vanity, "most likely" it's not going back, either.
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The most expensive tool is the one you buy "cheaply" and often...