Water resistant finish???

[BigRob777]

I was going to post this in the finishing forum, but it was off topic to some degree. I have a question, which I posted in the new woodworker's forum at yahoo, but nobody answered. I am making laminated bottom trays for Christmas, with exotic wood sides. The bottoms are made from baltic birch plywood (1/4" thick), with either bubinga, or beeswing makore' veneer laminated to it, with contact cement.

My question is this: What finish should I use, for trays that will inevitably get wet from time to time, to protect the wood and the lamination? It has to be relatively food safe also. I'm thinking of using a very thick minwax sanding sealer, followed by several coats of high gloss poly. What do you think?

Here's a pic of the laminations:

Makore' - - - - - - - - - - - - - - - - - - - - - - - - - - -Bubinga

Thank you,
Rob

 

[dubdrvrkev]

I would think spar varnish would be the most water resistant, isn't that what they use on boats? I just use waterbased poly on my trays though. I have been using Mahoney's Utility bowl finish (walnut oil) on all of my utility stuff lately and am happy with it. Real easy to work with totally safe.

 

[BigRob777]

Thanks Kevin,
I think you're right about the spar varnish. People don't generally eat right off of the tray anyway, but it should be fine. I'm hoping to sell these, along with pens, stoppers and coat racks, in the next few years and I need to get the process down. I also want to give my family good gifts. I'm such a curly wood nut, that I'm going to make ours out of curly Anigre' or curly cherry. I got some veneer that was spectacular and it's enough to refinish all of the doors in my house, on both sides.
Rob
Rob

 

[GBusardo]

Rob, Problem with Poly (or any film finish) is that if water does get under the poly, it will blister and be a pain in the butt to repair. On the other hand, it it probably one of the most durable finish I know of. Having said that, if it were me, I probably would go with water based poly over a sealer. Most all finishes are food safe once cured. So that is not a concern. One other thing I just thought of, how about that thick coating (epoxy?) they use on bars? I am sure I seen it in a Rockler catalog. Whatever you use, I am sure they will come out great. Good Luck

 

[BigRob777]

Gary,
Did you mean that you'd choose water based poly, instead of a sealer, or over top of a sealer? I was wondering about a water based poly. I've never used one before and I'd heard that they were good. What's a film finish? Finishing has always been my weak link.
Thanks,
Rob

 

[GBusardo]

Rob, Sorry if I didn't make sense. A film finish is any finish that sits on top of the wood, and doesn't sink in.
I would use a sanding sealer first, then apply my finish. The reason I would use a sealer first is its easier to sand than the regular finish and all I am trying to accomplish with the first coat is a smooth surface for subsequent coats.
The reasons I would use a water based is poly is:
It's easy to clean up
The odor and enviromental factor
It cures fast, so not only does it speed up production, it keeps the dust nibs down.

Some other thoughts.
Don't use a wipe on poly, because the coats are not thick enough to give you much water protection.
If the pores on the wood are very large, you might want to fill the pores first to get a smooth surface. You can do this with the finish, but you would have to apply, then cut back quite a few times before the pores are filled. You can also use a grain filler (not the stuff you fill nail holes with) which is easy to use and will fill the pores with one application.
If I am still not making any sense, check out woodmagazine.com finishing forum. Those guys are GOOD

 

[BigRob777]

Gary,
If you're not making sense, it's only because of my lack of knowledge. I have 3 years of Wood magazine to look at, while I'm laid up in my recliner and I do remember an article or two on finishing. Since I started turning, I haven't read my mags, so I'm going to take some time and do that. I do remember watching Norm Abrams use a filler. Do they come in varying colors? I will do some sanding first, up to 320 grit. I'll hand sand some to 1,200 too. Neither grain is open, escept for the mahogany sides, which I'm not as worried about. Thanks for the crash course. You're making a lot of sense. I'll get the water based poly, to go over my sanding sealer. I guess they're compatible?
Thanks,
Rob

 

[GBusardo]

Hi Rob, Yep the fillers come in different shades, but you probably won't have to deal with that if the grain is tight. I have used the filler on quarter sawn oak and it came out like a sheet of glass. I have never had a problem with a sealer or filler having compatibility problems with water based poly, but make sure its dry, just in case. I tried to scan some pages of a finishing book to send you in email, but after scanning, I could not read the text. Sorry about that. I can copy and send in snail mail if you would like. Just send me an email with your address. Oh by the way, If you go to www.woodmagazine.com, there is a searchable index in there somewhere. There are articles in the Sept 2005, Sept 2006 and Oct 2004 that might help you out.

 

[BigRob777]

Gary,
Thank you so much for all of your effort. I will most certainly check out that site and see what they have to say. I think your advise may be enough for me though, but I'll still check. Can you e-mail me with your shipping address? I want to send something your way, that I think you'll appreciate.
Thanks again,
Rob

 

[leehljp]

I have used two to three coats of tung oil followed by three to four coats of poly on several occasions over the years and they are still holding up to water without the slightest hint of water spots or stains. I have a small walnut coffee/drink platter next to my den chair, having made it nearly 20 years ago. It is still hard, shows the grain beautifully, and no water spots. I have never used a coaster either, even though LOML has chastised me for it for most of the twenty years.

The way that I do it is coat the item liberally with pure tung oil and wait 24 hours; wipe off, wait 24 hours, repeat 2nd time and sometimes a 3rd time. (3 times for larger pored woods). Wait a couple of days then polyurethane it - two to three coats, sanding with fine sandpaper (or fine steel wool) between coats; wipe down before succeeding coats of urethane. . Does super in waterproofing while providing a beautiful finish.

 

[ctEaglesc]

The issue no one has addressed is your method of construction.
One question I have is are these going to be turned?
You said a "tray" but they can be round or square so I am not sure I understand how you are going to make these.
I am not sure contact cement is the way to go if they are going to be turned and Yellow glue TBII may never fully cure depending on the size of the tray.
The issue of adhesive choice should be addressed before you worry about the finish.
BB plywood is extremely stable more so than the choice of woods that you will be using for the balance of the piece.
A little more information is needed about the construction before the finish is addressed.

 

[BigRob777]

Lee,
Thanks. I'm down to either a tung oil, or sanding sealer base. I was thinking of either tung oil, or Danish oil yesterday, as it would seem to seep into the wood pretty well. It sounds like it worked well for you. The sanding sealer that I have is really thick too, so that may not be my best option. I've heard that other sealers are thinned out poly, but I may still try it on one of them. I hope to do more of these in the future, as I have several hundred square feet of veneer.

Eagle,
The manner of adhesion has long been decided and was completed several days ago. I wouldn't dream of turning veneer on ply, as I'm sure I'd mess it up. The only question I had, was finish. I tried the yellow glue before and it left too many bubbles, even with 50 pounds of somewhat equalized pressure.

I learned how to veneer from watching Norm Abrams and his method worked great for laminating counter-tops. The veneer is much more flexible and sometimes wrinkly. Thanks for thinking of me and have a merry Christmas.
Rob