Newbie finishing goof

[StevenP]

Ok, don't ask how, but I used polyurethane when I was supposed to use alkyd varnish. Yes, I have a test piece, but in spite of that I applied the poly to one work piece before I realized that something wasn't right. Since then I have learned that poly and alkyd varnish are different finishes of the same 'family'. So now my question is this, do I need to remove the poly in some way before I apply the alkyd varnish, or can I simply apply over it? If I can apply over it, should I apply a coat of the poly to all pieces for consistency? If I need to remove the poly, what is the best way to do it? Or, do I need to trash the piece and re-make it?

Thanks for the help,

Steve P.

[MikeG]

The question that comes immediately to mind is, what is the concern here? Just continue on with the poly. So you get a little more protection and the piece won't scratch quite as easy. Doesn't seem to be a big matter of concern to me.

Well, I suppose you have a good reason. Poly is harder and slightly more brittle then a non poly varnish and since cured coats don't meld anyway you should be fine putting a non poly on top of a poly varnish.

The only reason I could see to apply poly to all the other pieces also is if there was a tint difference in the final results.

[George]

What's so bad about urethane resin that you'd overcoat it? Publicity?

If you do over coat, scuff at about 320 range to give some tooth, and have at it.

[SteveC1280]

What's wrong with the poly?

Remove the 'remove' in my address to e:mail me.

[J. Clarke]

There seems to be some information missing. What circumstances make it necessary for you to use one or the other? Or did you start a project with one and now have a mismatch due to using the other? If there's no compelling reason not to use polyurethane then just keep on with it.

[Preston Andreas]

Both are varnishes. In fact, the typical poly you buy in the store is an alkyd varnish modified with a polyurethane resin or a uralkyd. The poly is a more scratch resistant varnish. I would keep with the polyurethane if you could. If you have to remove it, you will either have to use a stripper and/or sander. You can apply the pure alkyd varnish over the polyurethane and vice versa because they are compatible finishes. As per instructions for both types, lightly sand between coats so the coats will adhere to each other.

Also, remember, there is a spar varnish and spar urethane. They are softer and more flexible to account for more wood movement such as found outdoors. They also have a UV protectant added.

[StevenP]

First off, thank you for all the helpful responses. Since so many people asked why I don't just stay with the poly, I feel compelled to answer. Essentially, I am using this otherwise trivial project, (drawer organizer for a kitchen drawer made from oak). to practice a couple of finish techniques. 1. I filled the oak grain by sanding up a slurry with Danish oil. 2. I am following the varnish finish technique as was described in the February FWW.

I will scuff up the poly that I applied and go forward from here, hopefully learning more as I go.