This may seem a simple question, but here goes ….
I need to protect some new wood against the weather; once I am finished, I doubt that anyone will ever maintan it. Out here, we have little moisture, but a LOT of strong sunlight.
I see there are several types of products out there. They seem to fit into four groups: paint, shellac, polyurethane, and ‘spar varnish.’ What are the strengths of each?
The same issue arises with another project – only on this other project, it is indoors, the coating will be applied to plastic, and the coating will be under water. (It’s the bottom of an indoor pond.)
The information on the sundry containers say little beyond “outdoor” or “exterior.” Any suggestions are appreciated.
Replies
There is a decent article at http://www.onthehouse.com/wp/20011126
Urethane products will typically amber some. Paint will block the sunlight due to the pigment. Shellac is only an interior finish.
That is a very good link ..... thx.
We used to get the Carey Brothers' radio show here. In regards to some other comments that have been made in this thread, the Carey Brothers asserted two things:
- Deck sealants (like Thompson's) are waz-based, and thus have short life in sunlight. (I did notice the ones at the store claimed a 3-5 year life); and,
- Epoxies -all of them- degrade quickly in sunlight.
For everyone .... my two projects are in this condition right now:
- The outside wood has two good coats of 'spar urethane.' I like the way the product soaked into the wood. Perhaps I need to paint over that.
- The indoor pond WAS painted with a pigmented shellac, but peeled off in large strips. I plan to drain and refinish it in the next two weeks.
Edited 6/23/2009 4:47 pm ET by renosteinke
renostinke
I used epiphanes on my black walnut exterior trim and it lasted over 4 years before the wood started to fade really bad.. now after 6 years it's time to strip it all off, sand it down to unfaded wood and revarnish it. Since the materials alone will come to almost $3500 not to mention something like a year to strip and sand, I give up.. Next time it's going to be painted (which seems like a real crime to paint black walnut)
Paint is the best protection against the sun; if you want a clear finish, find one with UV protection. I don't think form of shellac has that.
Maybe there's an epoxy paint with UV protection, since you say maintenance will be a problem.
But no finish is going to hold up forever. Use a material that has the best weather resistance- cedar, redwood, cypress, white oak, & Ipe are all good choices.
As far as paint for underwater? That seems like a tough job for any finish. Again, maybe an epoxy, or a pool paint.
"Maybe there's an epoxy paint with UV protection, since you say maintenance will be a problem."
Doubt it. Most epoxies are coated with an opaque urethane for UV protection.
WSJ
Well, I did say "maybe"
<G>
I try to avoid painting, so I'm not up on a lot of the new paints. But it sounds like the OP is kind of asking for the impossible. Or at least his customer is.
Shep;
While you are absolutely correct that shellac is not suitable for outdoors it actaully has a great deal of UV protection if used indoors.
Yeah, I know. I like shellac a lot.
But the OP was asking for an outdoor, and underwater, finish. Shellac, while versatile, isn't good in those situations.
"This may seem a simple question, but here goes ....
I need to protect some new wood against the weather; once I am finished, I doubt that anyone will ever maintan it. Out here, we have little moisture, but a LOT of strong sunlight."
White latex if nobody will see it, otherwise a decent pigmented deck stain.
WSJ
Shellac is not good in these applications.. If you use Varnish use a great marine tyype spar Varnish.. Epiphanes is the best and it's worth every penny.
It however is terribly expensive and difficult to apply properly.
For that indoor pool to coat plastic I'd visit an automotive paint shop and get a two part primer/sealer and topcoat with a compatible urethane enamel. After carefully sanding and cleaning the plastic surface. - r
Wow would that ever be expensive! I'd visit a pool supply store.
Yeah! Ha ha! but he said it was indoor so I figured it wasn't too big. plus it was plastic which is a challenging surface for paint. The other thought was a marine supply center but boat paint is just as expensive plus has additives to keep things from growing on the hull which seemed contraindicated in this case. - r
Indoor pool? Plastic? I'd visit a pool supply store rather than try to adapt something else.. If the wood is outdoors and you want to show off the wood Marine spar varnish is perferred because of it's UV protection.. Bottom paints have the stuff to prevent marine growth not spar varnish
"Pool" is slightly misleading. This is a "POND." That is, a plastic basin with gravel. plants, and fish in it. There is also a small waterfall at one end.
Sadly, traditional varnish will need periodic reapplication; even the good stuff Frency mentioned. There are some "two part" products designed to look like varnish (ambering) and they last longer; however, the sun will eventually win. It is better to stay on top of it (with a sand and re-coat as needed, no matter what The two part will just give you a longer time between re-coats.
Here is a popular two-part for boats:
http://www.awlgrip.com/products/search/pages/Awl-Brite.aspx
Brace yourself prior to pricing.
I really appreciare the comments so far.
I suppose I ought to be a vit more specific. Not that it changes anything - but a better description might help explain wht periodic maintenance isn't going to happen.
Ever see one of those boards - this one will be in a trailer park - that has all the electrical meters on it? Well, I'm making one of those. This one is free-standing (not attached to a wall). Unhappy with the results I've seen when plywood has been used, I'm using 2x6 T&G instead. I used Y&G rather than, say, pressure treated lumber because I want the boards to move together, especially where there is a joint.
While I avoided paint ... I've noticed how paint tends to peel .... I just might add a layer of paint atop the varnish I've already applied.
A good paint should give you a much longer life than a clear coat because the pigments more effectively block the UV light. You need to take care in applying paint over a varnish as it will leave a hard, glossy finish that it will be difficult for paint to adhere to. I would recommend either sanding to dull the finish or a primer designed to stick to glossy surfaces, or best of all, belt and suspenders, do both.
If your concern is about peeling paint here's what you need to know to get it to stop peeling..
Wood you buy is pretty green.. moisture content can be between 21% and 7% Even Kiln dried.. green wood when it dries shrinks and since paint can't shrink it is easy to peel. There are two real solutions. The best is do nothing for a year and then paint when the wood is really dry (after an extended dry spell). if you are in a hurry and want the wood soon.. you can rekiln dry it yourself.. If you have a dehumidifier make a plastic baggy the size of the wood plus a little tape the baggy to the air intake and run the dehumidifier for 30 days (you'll be amazed at how much moisture it pulls out of supposedly kiln dried wood) then you can paint without fear of peeling (assuming the wood is clean)
I'd use paint. Start with a good primer- Cabot's Problem Solver (solvent based 100% alkyd) is one I'd recommend. I'm not a fan of latex primers for new wood. I'd prime everything before assembly including the t&g's though it sounds like it might be too late for that. I've seen cases where the wood has shrunk and you end up with racing stripes (bare wood) at the joints. I'd sand the varnish before applying paint. Use a good latex topcoat (Duration or SuperPaint) and you should be good to go. If there was no varnish or previous finish one other alternative is an oil based stain stain such as Cabot's OVT. Sand to remove mill glaze and apply before assembly followed by another coat after assembly. It will eventually fade but recoating is easy- no scraping needed.
"There can be no doubt that Socialism is inseparably interwoven with totalitarianism and the abject worship of the state…Socialism is in its essence an attack not only on British enterprise, but upon the right of ordinary men and women to breathe freely without having a harsh, clammy, clumsy tyrannical hand clasped across their mouth and nostrils" -Winston Churchill
Edited 6/24/2009 10:14 am by jc21
Edited 6/24/2009 10:16 am by jc21
Can you use MDO for the "wood" and paint that?
The wood is up. I wanted 'real' wood for it's ability to hold screws; there's a lot of electrical equipment hung from it.