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clear finishes

Jeff Jilg

Jeff Jilg

Joined
Apr 9, 2004
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Location
Austin, TX
Website
www.woodturner.org
The current Fine Woodworking (June 2006) has an article on pp 42-45 about clear finishes. Many finishes have a slightly bluish or yellowish cast. The article discusses 3 types of "very clear" finishes:
- water based finishes including acrylic, polyurethane, varnish, and shellac
- clear shellac
- CAB lacquers

I am interested in the 3rd type. CAB = cellulose acetate butyrate. Most brushing laquers are nitrocellulose based. The article states that CAB lacquers must be sprayed. Has anyone tried these lacquers? Are they noticeably clearer than nitrocellulose lacquers?

In the intro of the article they state that many people like the slight yellowish hue which comes with most finishes. However, as the article states, sometimes people want to get a water-clear finish on their piece.

One of the CAB lacquers pictured in the article is a spray can of "Plasti-Kote Super Lacquer".
 
I prefer using a catalyzed conversion varnish. It is clear, handles and sprays just like laquer and is ready to sand in about 15 min. Has a working pot life of 6-8 hrs. It dries hard as a rock and completely cures in a couple days. It thins and cleans with laquer thinner. It can also be tinted if you wish. DO NOT try to spray without a cartridge filter type mask and a long shirt w/ a spray sock is not a bad idea. I love the stuff. Used it on kitchen and bath cabinets for years. A retarder can be used. I usually do.
Jim
 
It is not really the lacquer finish that has an amber cast, but rather the effect that it has on the wood, essentially the same effect that you see if the wood is wetted with lacquer thinner, naptha, or mineral spirits to enhance the grain and color of the wood. Although when lacquer is exposed to UV radiation, it will gradually turn slightly amber over a period of many years. CAB lacquer is less susceptible to the effects of UV and therefore has less yellowing. In the case of water based finishes, the color of the wood is not affected which also means that the color and grain are not enhanced because the water based finish basically sits on top of the wood rather than soaking into it. As the water in the emulsion evaporates, the tiny particles of finish in the water based emulsion blend together and settle on top of the wood, being too thick to soak into the wood. But, I would not necessarily equate this characteristic with being clear. For instance, if you applied regular clear polyurethane finish and water based polyurethane onto a non-wood white surface, the difference in color would not be noticeable. Over a period of years, the water based poly would yellow as much, if not more than the VOC based poly.

Bill
 
The eye loves the familiar. How often do people comment on the "warm glow" of wood? That glow is yellow or amber, because that's what they're accustomed to see. So's a romantic fire, which is why we don't have the low blue flame in our gas fireplaces.

Have a friend who builds and sells boxes finished with "environmentally benign" water-based finishes. He wouldn't have it any other way. When I was next to him at a booth a couple years back, people commented continually on how the wood lacked character, where the bowls I was selling had it. Even the ones some call "plastic" with full-gloss urethane. They had the wood look. The boxes didn't.

Blue means white to the eye, of course, (remember laundry "bluing?") and those finishes that are initially a touch blue will probably seem more white as they age. My advice - try it, give it some sun, give it some knocks to test it, but don't bet the farm on it. You could end up with a lot of pallid boxes at the end of the show that nobody bought.
 
Jeff,
I am not an expert on all lacquers but do use one brand and have used it for quite some time. Mohawk Finishing Products . Since I do not use large quantities, I use aerosol products (finishing turned pieces, very little flat work) which serves me well. I use Pre-Catalyzed Clears and C.A.B Production Topcoat Clears as well as various sealers. I love these products and find them very easy to work with and they give me the results I want. The following link is for aerosols Clears and Sealers

If you navigate back you will find all sorts of products that should be of interest.

Hope you find this info helpful.

Ed
 
Thanks guys. I read thru the responses a couple of times.

Bill - the article somewhat stated that water based poly's are clearer. But your statement makes sense that both types of poly's will yellow over time.

Michael - that is an interesting comment, that people like yellowish wood. I guess you're right, it's what we're used to. I like it too. The finishes that soak in seem to highlight the grain as well.

Jim - I have a cartidge mask that is for organics. I use it for all finishing.

Ed - thanks for the link, just what I was looking for.

Overall I am happy with the current finish I'm using - Formby's Tung Oil Finish. It's easy to work with and give good results. But the long drying time soaks up a lot of dust from the shop. That means I do a lot of sanding to remove the dust nibs between coats. Plus those dust particles probably don't add a lot of clarity to the final finish. So that's why I'd like to find some alternative.
 
How many coats?

Jeff:
Just as a matter of interest, how many coats of the tung oil finish do you normally apply. I have just tried Behr Scandanavian tung oil finish (Home Depot Canada). After 4 coats I'm not really pleased with the results. Am I skimping and hoping for too much too soon?

Thanks
Michael
 
Usually 4 coats. First one soaks in and never becomes glossy. Second sometimes soaks in and sometimes doesn't appear to, depending on the wood. The 3rd and 4th coats always stay on top. I usually put on sufficient coats to provide some protection, but there is usually some grain pores evident which did not get covered. To me, this leaves the piece looking finished, yet you can tell there is wood underneath. To put more coats on would completely cover it and that's not the effect I'm looking for - but that is just an opinion.
 
Jeff Jilg said:
Bill - the article somewhat stated that water based poly's are clearer. But your statement makes sense that both types of poly's will yellow over time.............
Click to expand...
I suppose that one could draw a conclusion from the article that water based lacquer is clearer than solvent based lacquer because the article's "broad brush" treatment lacked some "clarity" and "glossed" over some of the information.

Bill
 
Jeff Jilg said:
Usually 4 coats. First one soaks in and never becomes glossy. Second sometimes soaks in and sometimes doesn't appear to, depending on the wood. The 3rd and 4th coats always stay on top. I usually put on sufficient coats to provide some protection, but there is usually some grain pores evident which did not get covered. To me, this leaves the piece looking finished, yet you can tell there is wood underneath. To put more coats on would completely cover it and that's not the effect I'm looking for - but that is just an opinion.
Click to expand...

Do you buff it afterwards or just leave it?

Michael
 
Each coat gets lightly sanded with 600 grit and wiped off before the next coat. Last coat gets 600 grit, lightly sanded and buffed with rouge, white, then wax using 3 different buffing wheels.

It would be nice if the last coat was smooth, but like I said the dust nibs are in there.
 
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