Water Based Poly over BLO?

[Matt Meiser]

A friend of mine is building a kitchen table from maple and after seeing a sample of a piece of maple I had put BLO on, he decided to go that route. I recommended something more durable over that to protect from spills, etc. He wants to use water-based poly. Will that work? I'm thinking not. My suggestion is probably oil-based poly after letting the BLO cure for a week. Does that sound good?

[Jeff Sudmeier]

Matt,

I would have the same thinking as you. I know that water and oil don't mix, but I dont' know how that relates to finishing. As always, maybe a trail on some scrap is due...

[Cecil Arnold]

Matt, if you will apply a thin coat of shellac (1-2 lb. cut) you can put almost anything over dry BLO.

[Jim Becker]

You can put water bourne products over BLO once it is fully cured, but a barrier coat of de-waxed shellac is generally a good idea. If you don't want to materially change the color of the project, use blond or super-blond shellac for this purpose. In fact, it's an even better idea because it adds back a little of that "warmth" that is missing from many water bourne products including WB Poly.

Do understand that WB poly doesn't have anything close to the same durability/abrasion resistance that solvent-based polyurethane varnish has. There is a good article on this in the July 2005 issue of Woodshop News by Bob Flexner. He mentions this in the context that there is a regulatory move to eliminate solven-based polyurethane varnish from the marketplace, even though it's only really used by consumers in quart cans. (Personally, I don't use the stuff, but it's the most available finish for the masses on the market)

[Greg Torok]

Do understand that WB poly doesn't have anything close to the same durability/abrasion resistance that solvent-based polyurethane varnish has. There is a good article on this in the July 2005 issue of Woodshop News by Bob Flexner. He mentions this in the context that there is a regulatory move to eliminate solven-based polyurethane varnish from the marketplace, even though it's only really used by consumers in quart cans. (Personally, I don't use the stuff, but it's the most available finish for the masses on the market)

Not sure about this one... I finished our kitchen table with 6 coats of water based poly (Tripp Super Poly). My wife runs a home based daycare, we live near the ocean so all beverages leave water rings on the table, kids do the best they can at destroying stuff, and the surface finish had held up MUCH better then expected. Kids spill stuff, we never dry the water, we have even used alcohol to scrub off permanent marker. This table gets used and cleaned and abused far more then most tables.

The table is made of 'something similar to soft maple' and relatively soft.... the kids are wonderful at putting dings in the surface, but scratches to the surface finish seem to be about as durable as the oil based I've used.

While it may not be quite as durable as the oil based (based on lab tests), I think it's certainly something close. The 6 coats can also be brushed on in a single day with the water based.

[Greg Torok]

The water based poly was applied over several coats of danish oil, after letting the oil finish cure for about a month ( I was doing other things).

Shelac is probably a good idea, but I didn't have any

[Scott Parks]

Matt, I think it will work.

Target Coatings sealer can be applied over anything, I beleive, even BLO. Then you can apply any water base poly over that.

I just rubbed BLO on to a maple vanity a couple days ago. Later this week I'll be finishing it with Target sealer and poly.

My kitchen table is covered with 3 coats of Target sealer, and 2 coats of Target poly. If you "bake" it with a hair dryer after it is cured, it will be very, very durable!!! Here's my table 4 years and 2 kids of abuse later.... Looks like new! Tough as nails, and that's the truth!

[Chip Olson]

You can put water bourne products over BLO once it is fully cured, but a barrier coat of de-waxed shellac is generally a good idea.

Can you expand a bit on that? I'm looking at WB poly over BLO for my kitchen cabinets, and want to make sure it won't fall off in a year or something. :-)

[Cecil Arnold]

I'm not Jim Becker, but I will try to expand in my limited way. Shellac is a barrier coat and is compatable with everything I have run across in the way of finishes (someone will come up with something it may not work with). I think you could even use it to seal latex house paint if you decided to overpaint with enamel, the latex might let go, but the enamel would hold on to the shellac which would hold on to the latex. Another widespread use is to seal knots in SYP when you are building utility cabinets, before you put on the finish coat--thus the wide distribution of white pigmented shellac(WPS). There is a newer substitute for WPS, called Kilz, but IMHO it is not as good as the origional. Additionally, you can use some of the different refinements of shellac to give furniture a different look. For example, garnet shellac will really pop the grain on mahogany, or if you want to warm a piece up you can use orange shellac under your clear coat. I have a piece under construction that is mahogany and tiger maple that is/will be coated with BLO, followed by blond shellac, and finished with nitro cell. laquer. I do not anticipate any problems with this finish schedule and have used it or something simuliar many times in the past. BE SURE YOU USE DE WAXED shellac under your clear coat. Shellac is best bought in flakes and disolved in alcohol. You can speed up the process by using a coffee grinder. It will still take a couple of hours, but otherwise will take overnight. Mix only what you think you will need, the shelf life is only a couple of months. If this stuff will seal pine knots, then BLO is not a challenge, and some of the classic furniture that is shellac finished still looks great, even some of the not too classic stuff that has been painted over. Good luck.