polyurethane woes..

[John Newell]

One other thought-lette: I've had terrible luck with aerosol poly of several kinds, including recently Minwax Polycrylic. YMMV...

[David Duke]

Another option would be either the Bartley or General Finishes gel varnish.

[Mike Henderson]

Unfortunately, spraying an oil-based finish such as polyurethane varnish is a very yucky task...the over-spray will turn your shop or booth into a big fly trap since it takes Soooooooooo Looooooooonnnnnnnnngggggggg to dry. If you can spray, there are better finishes including water bornes that contain polyurethane resins if the customer insists. And there are also finishes that will have greater clarity with no real loss in "durability".

If you must use oil-based poly, brushing or wiping is how I'd do it, but only after good surface preparation including sealing/flattening with de-waxed shellac. And then a good brush and appropriate thinning is necessary to get a good flow-out. Wiping is easier, but will take many more applications to get to the same film thickness.

If you're not comfortable with those ideas, I agree that you should consider subcontracting the finish work.

In no way was I suggesting using an oil based poly. I use almost all water based finishes now including poly. I don't even think of oil based finishes any more so I didn't specify water based.

The water based poly dries very quickly - not as quickly as solvent based lacquer but a LOT faster than old time oil based varnish.

Here in California the VOC rules are essentially forcing everyone to water based. I was surprised the first time I made the switch - the water based works very well - I really don't miss the oil based.

In spraying a dining room table with poly - or lacquer - it'll take about three coats to get a good finish. The first one will disappear into the wood (unless you prep the sruface with something like dewaxed shellac), the second will give coverage but will have thin areas, and the third coat will give you a good long lasting finish. I'll repeat again - for a dining room table you need a finish that will stand up to water, heat, things being dropped on it, and other abuses. Water based poly is a good finish for a non-professional to use but will not take a high gloss like lacquer will. If your customer wants a satin finish, poly will work very well.

Mike

[Jim Becker]

Sorry I misunderstood you on the the oil-based / water borne thing, Mike. But the only real "extra" property that polyurethane adds is abrasion resistance--it was primarily designed for floors. (That abrasion resistance is why it will not rub out as nicely as other alternatives) It will ding the same as anything else, has no additional water resistance than most other finishes and since poly doesn't like to stick to itself without "help" in the form of, believe it or not...abrasion...between coats, may not even be as durable as other finishes if it's not applied absolutely correctly.

There are some wonderful water bornes that give terrific performance as well as "good looks". I primarily use Target Coatings products. The USL is really easy to work with, "burns in" like NC lacquer and dries fast. (It can be brushed, too, although I'd always prefer spraying) They have a hybrid alkyd varnish product that I really like now that I've used it, a conversion varnish product and some other things. (even a water borne polyurethane for when that's the right thing) There are a bunch of other vendors with equally diverse product lines.

Yea, I know...I'm ranting. Sorry. I'm just sad that the retail shelves are stocked to the top with poly and all the other good stuff is often missed out on because of marketing.

[Matt Droll]

Mark,

Now that you've specified water borne poly, it screws up my method, but for anyone else who may be interested, here's what has always given me glass smooth finishes with poly.

Put a base coat of shellac down to seal the wood... dries fast, then sand it out (I know every poly manufacturer will tell you not to use shellac as a base coat, but I not so humbly disagree). My prefered poly is Zar, but take your pick, and thin it with 2-3 oz Mineral spirits per quart. An air temp of 70 or so is good for actual application. Load up the brush, slop it on the piece, and work it up into a lather making somewhat of a foam, then give it a couple of brush strokes to smooth it out and leave it be (yes there will be tiny bubbles left, but they will break and self level). Continue working along until you've finished the piece. Rub down with 0000 steel wool before a second coat. After the last coat, a light rub down with 0000 steel wool and some minel oil will make it like glass, although will dull the gloss if that's what you're after. Everyone I've mentioned this to looks at me like I have six heads (when I mention the "lather" part, but I'm telling you it works.

My .02. It's more time consuming to be sure, but I've always prefered poly to lacquer... probably not something to experiment with in this situation though!

-Matt

[Mike Henderson]

I haven't used the Target lacquer but the problem I have with lacquer for a dining room table is that heat melts lacquer (at least the lacquer I've used). If you put a hot dish on a lacquer finish it'll leave a mark. This won't happen with catalyzed lacquer but there's a bunch of problems in applying that stuff. A few companies make pre-calalyzed lacquer but it's not as good as real catalyzed lacquer and will mark from hot dishes.

Anyway, that's the main reason I recommend poly for a dining room table - it will not mark from a hot dish (unless the dish is extremely hot, I suppose).

I'm not a finishing expert so if there are other recommendations for a finish that will stand up to heat, water, and other abuse, please post. I'd appreciate the info.

Mike

[Jim Becker]

Mike, you'll be refreshed to know that Target USL, while having some desirable properties similar to lacquer, is an acrylic product...just like almost every other water borne. The word "lacquer" in the name signifies those properties (burn-in, etc) but it's not "lacquer", per se...

[Joe Chritz]

First is to talk the client out of a sub premium finsih.

Second is to hire it out.

For a table top I would go with a wipe on like Waterlox or Arm-r-seal or spray a conversion varnish.

There are better finishes than poly, especially for a table top. The soft nature of the poly isn't a bonus for a table.

If they insist then multiple coats and have them sign off on the finish.

As already mentioned spraying poly isn't really a pleasant experience, especially for everything in the immediate area. All that overspray that settles as dust when spraying lacquer or USL settles as wet poly when spraying it.

Joe