wood finish

[Chip]

I got a question for the woodie builders out there,,,,

Is there a problem of using a penetrating oil base transparent stain and then covering it with water based polyurethane on the exterior of a trailer or should I just stick to like materials thru out,,, It is gonna be topped over with a couple coats of spar varnish with UV inhib's,, after the poly is dry,,

thanks fer tha help in advance

chipper

[Hardin Valley Magic]

Chip: use lifes lessons stick with the same, thats the way I did it.

[ralaco]

Water based over oil doesn’t work but
Oil over water based is fine

Raul

[Chip]

Raul,,, I was thinking that one would work over the other but couldnt remember which,,,

thanks a bunch for the clarifications,,

chipper

[doug hodder]

I think Raul is right...but just for grins, check the info on the cans..sometimes when using different manufacturers and bases you can get into trouble...I know Dean had a problem with the paint he shot over his bullet primer...and it was supposed to take anything.....I know you can't shoot lacquer over polyurethane oil base...found that out the hard way...oh well...the wrinkles make it look more vintage..prior to lots of sanding.. ..but you can shoot polyurethane over lacquer....I'm with Hardin....
doug

[madjack]

Chip, instead of shooting poly and then spar varnish check out MinWax ClearShield...it is a UV,d poly and would eliminate the need for the spar varnish...I can vouch for its effectivness, it is a damn good product...
madjack

[Ross Wade]

I have NEVER had a problem using an oil based stain on raw wood and then appling a water-based finish over top. The major key is to let the oil based product DRY throughly. I used an oil based Gel stain on the inside and galley of our first teardrop, then used an oil based poly in the galley and a water-based poly in the cabin and NO PROBLEMS for me

Now, sure as heck someone does this, the finish will peel off.

All I can say is, I have had no problems with this procedure. But I would strongly recommend that you run a few samples to double check the adhesion.

Ross

[Juneaudave]

Ross' suggestion to run some samples is a good one. A sample panel finished with the stains and finishes you intend to use will give you a good idea of the look, application techniques, and finished product.

[48Rob]

Chip,



Latex (water based) can be applied over oil based products.

If oil is applied over latex, it will soon fail.

Latex has much more "give" than oil based products.

That said, you'll almost always get a better finish by staying with one, or the other, as when combined, they tend to tug at each other.

The general exception is in a case like yours, where a penetrating stain is being used.
Apply, let it dry, sand or scuff, then apply the (latex) clear finish, but just, the latex finish, spar will likely fail if put over a latex clear...it is far more resilient than some varnishes, but still won't "stretch" as much as latex.

There are some VERY good latex clear finishes out, though I can't say the same for stains...

I'm unclear on why you want both latex and oil clear?

Good spar will give great protection, though the finish will never be "hard".



Rob