What type of finish

[woodknots]

I'm making a sign for a customer that will be hung out side and I'm trying to figure out what finish i should use. The sign will be made out of baltic birch ply and the backer will be red cedar. I'm not adding any color and i don't care if the finish turns the ply a amber just need good protection. Thanks Jeff 

[fredfret]

Spar varnish.is what I use for outside projects. It will need to reapplied id a couple of years. A more difficult finish would be epoxy like bar finish but I don't know how well it weathers.

Fredfret

[WayneMahler]

I use Minwax Helmsman Spar Urethane and it works well for me. As FredFret said it will need to be reapplied in a couple years. I normally apply 3 to 4 coats sanding between coats lightly. This can be found at many places including the big box stores. 

[Scrolling Steve]

Like the others have said, I use spar varnish and or spar urethane !

[NC Scroller]

I hate to give you bad news but Baltic birch is NOT an exterior product.  It is for interior use only If it is exposed to the weather it will not last.  I am not talking years.  I am talking a few months at best.  I would cut it out of two pieces of red cedar using one as the backing colored or stained or painted to give contrast.

[DWSUDEKUM]

Actually if you are going for lasting power you need to do 3 things 

1) Seal the grain of the wood with a good water proof / resistant sealer like tung oil ( the Chinese used it for thousands of years to water proof their boats)

2) Choose the wood you want to use carefully - Cypress, Cedar and Oak and marine plywood tend to be good contenders - a lot is going to depend upon how thick you are making your sign.

3) When you top coat the sign use several thin even coats not big heavy ones making sure you get the nooks and crannies or the weather will get in that much faster.  Spar Varnish is what the boat industry traditionally used on boats for this kind of thing.

 

Looking forward to seeing your sign when you get it completed.

 

DW

[Lucky2]

DW, it's fine to use white oak outdoors, but, you should aviod using red oak for outdoor projects. White oak will stand up to the conditions, red oak won't last nearly as long.

Len

[DWSUDEKUM]

DW, it's fine to use white oak outdoors, but, you should aviod using red oak for outdoor projects. White oak will stand up to the conditions, red oak won't last nearly as long.

Len

Actually I do not use oak for outside things but if I were it would be White only.  Depending upon how long you expect it to be out of doors, how directly the weather can get to it that kind of thing will determine what woods and finish you should be thinking of using.

DW

[dgman]

Personally I would not make any scrollsaw project for outdoors unless it was painted, and I hate to paint!

[EarltheScroller]

I hate to give you bad news but Baltic birch is NOT an exterior product.  It is for interior use only If it is exposed to the weather it will not last.  I am not talking years.  I am talking a few months at best.  I would cut it out of two pieces of red cedar using one as the backing colored or stained or painted to give contrast.

Have to admit this was my first reaction. Spar varnish is going to be fine but Baltic Birch is not great. I built a small lighthouse to be displayed outside in the hot AZ sun. It's painted so all the edges are will protected and after three years it is literally falling apart. I would use only solid wood or maybe marine plywood if the owner is willing to keep refinishing like an avid boater will do.