Wood: Varnish & paint outside will it last

[Ian Gills]

OK, here goes.

I have added some oak trim as a surround to the PVC windows on the outside of my house to cover up a messy-looking caulk/paint job done on them many years ago by a previous owner.

I have varnished the wood with spar urethene and it looks great.

I tried and failed to use PVC instead because I had difficulty getting it in the sizes I needed. So shaping it proved far too tricky. So it is in oak and I prefered working with wood anyway.

My question is: will the varnish finish last on the oak or have I been crazy to do this?

It looks great but would paint have been better?

Was the choice of oak a good one? I could have used any wood but wanted to try a hardwood instead of the usual soft.

Any opinions please?

 

[Mort]

I think the spar varnish is about as good as it gets for a natural type finish. It's made for boats yes? That said, I think paint might have been a better choice from a lower maintenance standpoint. Looks like you'll find out for sure come next spring

Mort

 

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[Ian Gills]

Thanks Mort. I'll see how it goes. If all else fails, I'll be out with my white paint this time next year.

 

[Southern Man]

I have some exterior oak door sills that I spar varnished three years ago. I let them go a bit too far, but my painter sanded them back to bare wood and re-varnished with 4 coats, and they look OK but not as nice as when new. He used to work on boats and says that 7 coats is the bare minimum for a marine environment. He also suggests a single "maintenence coat" every year, and prep with fine steel wool better yet 3M sanding pads. That is, unless the finish wears through then I'll need to sand back to bare wood and start over.

I've found that a semi-gloss is the best finish because you can easily tell when it needs a new coat.

Oil based paint is basically varnish with pigment solids so it will protect the wood better.

 

[Ian Gills]

Thanks Southern Man. I will try to up the number of coats then.

 

[Southern Man]

Thanks Southern Man. I will try to up the number of coats then.

If you have a nice dry weekend like I did you can get 4 on in two days. With high humidity though it will take forever to dry enough between coats. The surface should be not tacky at all before you prep.

After using a pad, vacuum, then tack-cloth, then a clean rag with mineral spirits. If you prep like that and get all the dust out, with enough coats you'll get a finish that has depth like a high-end furniture piece.

 

[Ian Gills]

Yep, I have had that effect on my window sills indoors. They look like a piano finish.

For the trim outside, I am trying to finish the pieces before I install them. At least this time.

 

[Southern Man]

That's great if you can do that because you can seal all surfaces and ends. Then finish up with the last 2 coats in place.

I've seen some jobs where Sikkens was used. It is manufactured by a company that makes automotive finishes, but they make a product for exterior wood, like for log homes. It only comes in gloss, and is something like $60 per gallon. It goes on very thick- one coat. It does not, however, look nearly as nice as multiple thin coats of spar varnish, because there is no sanding/ prep/ dust removal.

http://www.nam.sikkens.com/product-category4.cfm?product_category=log-home

 

[Ian Gills]

Thanks. I was wondering what they used for log homes.