Best finish to use on the inside of your teardrop

[BlackCatRacing]

I am starting to make sawdust. Well almost. I am pre finishing my inside 1/8" birch plywood. I have a gallon of spar varnish which I would like to use up but am wondering if this will be to much VOC for a small space. Does spar varnish or all varnish still off gas after it is dried. If so for how long. I will not be using it until summer...
Thanks Patrick

[48Rob]

Hi,

Spar varnish may not be the best option for the interior of the cabin as it is a "soft" finish.
A regular polyurethane varnish will be more resistant to scratches and gouges.

Another consideration is drying/curing time.
Any oil product will off gas until cured/dry. A hard finish product of just one or two coats will be able to cure faster than several coats of spar, which goes on thick compared to poly.

Took a couple months for 2-3 coats of poly inside my trailer to fully cure and the majority of the odor to go away.
I used spar on the exterior, but didn't pay attention to any odors.
I'm not experienced with epoxy, but many find it a great sealer, with just a coat of clear or varnish over it to protect from UV.
The inside of a camping trailer will experience a lot of moisture, and sealing it well is wise.


Rob

[jonw]

For the interior I just used a couple of coats of satin finish Minwax Polycrylic urethane. It's low VOC (minimal fumes), water based (so cleanup is easy), and dries quickly. I wouldn't use it for exterior surfaces but for interior use it was perfect and has held up well.

[BlackCatRacing]

Thanks for all the good tips. Going with polyurathane...

[dwgriff1]

I did not want the all wood look. I want to emphasize my cabinet work.

Home Depot has texture paint. I applied that to the panels BEFORE I assembled, to create an almost sheetrock look, then painted the panels (again before assembly) with a couple coats of good oil enamel.

Since then i've done a 21' travel trailer the same way and it works well and emphasizes the cabinet work.

But, as they say, your mileage (and taste) may (and will) vary.

dave

[Thawley]

Thanks for all the good tips. Going with polyurathane...

FYI – if you're going for a matte or satin finish, most furniture finishers suggest using gloss on every coat but the last. Not a big deal if you just want to protect the wood. But it helps highlight the grain and character of the wood at it's best...

[BlackCatRacing]

Thanks Thawley, I do a lot of constrution and installed carsiding pine on the interior of a enclosed porch last year. I pre sealed all the boards and thought I had used spar varnish. I must of used polyurathane because that is what I had left over. Well I was really excited and got straight to work today covering all my interior sheets of birch. They looked great!! but as they dried they got less shiny. I looked on the can and it was semi gloss. Not what I wanted. If I lightly sand this and put gloss over it will it bring back the clarity??

[VijayGupta]

Yes, the final coat determines the sheen. Sand the penultimate coat with p400 and/or Scotch-Brite pads (maroon or light gray). This will remove any dust nibs and make a mechanical bond with the next coat.

I normally do full sheen up to the last coat. This is common, but the main reason I do it is that I custom blend sheens by mixing 5 sheen (dead flat) with 85 sheen (gloss) in measured proportions and I don't want to have to mix up all the intermediate coats.

Most finishes have a "critical temperature" below which they won't properly cure. For acrylics this is about 65 degrees.

Also most finishes take 2-3 weeks to fully cure. Proper temperature and lots of air movement (especially for oil-based varnishes that cure by bonding with oxygen) is important during the curing process.

RE: spar varnish. Spar varnish is a "long-oil" varnish, meaning it has a higher proportion of oil to resin in its formulation. This results in a flexible finish to enable it to accommodate movement expected in spars. It is a softer finish and less moisture excluding due to its higher oil content.

Polyurethane's main attribute (other than being cheap and easily found) is abrasion resistance. Disadvantages include long dry time (allowing it to pick up dust), significant ambering, less adhesion, little UV resistance, and almost impossible to repair.

Thanks Thawley, I do a lot of constrution and installed carsiding pine on the interior of a enclosed porch last year. I pre sealed all the boards and thought I had used spar varnish. I must of used polyurathane because that is what I had left over. Well I was really excited and got straight to work today covering all my interior sheets of birch. They looked great!! but as they dried they got less shiny. I looked on the can and it was semi gloss. Not what I wanted. If I lightly sand this and put gloss over it will it bring back the clarity??

[BlackCatRacing]

Yes, the final coat determines the sheen. Sand the penultimate coat with p400 and/or Scotch-Brite pads (maroon or light gray). This will remove any dust nibs and make a mechanical bond with the next coat.

I normally do full sheen up to the last coat. This is common, but the main reason I do it is that I custom blend sheens by mixing 5 sheen (dead flat) with 85 sheen (gloss) in measured proportions and I don't want to have to mix up all the intermediate coats.

Most finishes have a "critical temperature" below which they won't properly cure. For acrylics this is about 65 degrees.

Also most finishes take 2-3 weeks to fully cure. Proper temperature and lots of air movement (especially for oil-based varnishes that cure by bonding with oxygen) is important during the curing process.

RE: spar varnish. Spar varnish is a "long-oil" varnish, meaning it has a higher proportion of oil to resin in its formulation. This results in a flexible finish to enable it to accommodate movement expected in spars. It is a softer finish and less moisture excluding due to its higher oil content.

Polyurethane's main attribute (other than being cheap and easily found) is abrasion resistance. Disadvantages include long dry time (allowing it to pick up dust), significant ambering, less adhesion, little UV resistance, and almost impossible to repair.

Thanks Thawley, I do a lot of constrution and installed carsiding pine on the interior of a enclosed porch last year. I pre sealed all the boards and thought I had used spar varnish. I must of used polyurathane because that is what I had left over. Well I was really excited and got straight to work today covering all my interior sheets of birch. They looked great!! but as they dried they got less shiny. I looked on the can and it was semi gloss. Not what I wanted. If I lightly sand this and put gloss over it will it bring back the clarity??

Thanks for the very imformitve information. Glad to know my mistake will not be that bad.

[_Ryan_]

Great info guys, thanks!

[Wolffarmer]

I used danish oil on the interior birch plywood of mine. It does take a while to fully cure but as I pre finished the wood before assembling it had a few months to cure. I really like danish oil and the stuff I like the most is made by Tried and True. The stuff is easy to apply just takes a bit of time but usually you will have other tasks to do between applications. And I like the smell. I liked to slap some on a project in the morning and then go to work at a computer call center.



Randy

[droid_ca]

I stained a wood project recently thats a gift for a special someone. what would you use to go over min wax oak stain to seal it. like make a shiney coat like a uthane or a poly.

slow

I used 16 coats of Tung oil on this....Is that the type of finish that your looking for?

[Off Grid Rving]

on the Ogre Rv I used boiled linseed oil wiped on the plywood walls, it turned out beautiful and had a natural smell instead of anything chemical based.

so my vote is for linseed oil

[Wolffarmer]

I have yet to use BLO ( Boiled linseed Oil ) I have a can of it and will use it on something this wood working season. I like the Tried and True danish oil. Which is mostly BLO anyway and the T &T does not use heavy metal drying agents that most of the other Danish oil uses. The T&T DO is food safe and I have used it some cutting boards with good results.

Randy

[_Ryan_]

I was thinking I would use Minwax 209 Natural stain then Helmsman Spar Urithane for the birch on the inside my my TD. Birch has a tendency to stain blotchy so I was going to keep it natural with a bit of amber warmth the finishes will naturally provide.