Replies

1. 
   forestgirl | Nov 26, 2003 07:11am | #1

   You can tell whether it's oil-based or water-based by what they indicate for clean-up.  Paint thinner or mineral spirits for oil-based, water for water-based.  The solvent for shellac is denatured alcohol.  Lacquer=lacquer thinner.

   What to use depends mostly on what type of use the piece is going to see (e.g., a table-top vs. a mirror frame) and what type of look is desired.  An oil-based varnish will give more depth to the wood than water-based, for instance.  Shellac is a poor protector against many spills, but works fine for things like mirrors.  Personally, I don't go near Varathane for anything.  Get yourself a good finishing book (example:  Jeff Jewitt's "Great Wood Finishes" or Bob Flexner's book). 

   forestgirl Another proud member of the  "I Rocked With ToolDoc Club" .... :>) -- you can take the girl out of the forest, but you can't take the forest out of the girl   ;-)

1. 
   user-134407 | Nov 26, 2003 05:22pm | #2

   My frustration is that I have Flexners book, and I have trouble applying what he says because I can't select finishes based on what's in them.

1. 
   Tao | Nov 26, 2003 05:42pm | #3

   First, read Flexner's book again.   And again.  The information you need is in there.  It took me nearly twenty years of to gain all the knowledge he has put in there.  There are tell-tales in the description on the can, and in the product literature, which Flexner explains.  Look on a gallon can; sometimes there is information on the larger cans that isn't on the smaller cans.

   If all else fails, ask for a Material Safety Data Sheet, either from the vendor, or from the maker.  They are required by law to be made available to any purchaser.  They will list the solvents and resins in the finish. 

   But really, there are so few choices:

   Lacquer (cellulose nirate of nitrocellulose) hint: clean up with lacquer thinner.

   Alkyd - Hint: cleans up/ thins with mineral spirits.  Most pigmented stains and varnishes that are not polyurethane.

   Polyurethane - Says so on the can

   Drying oils:  Almost never Tung, even though it may say so in the name. -- either linseed oil with driers, or an oil-varnish blend.  Usually a blend.

   Waterbornes:  Coalescing finish with acrylic or urethane resins and a binder.  usually indicates on the can.

   Acrylics:  Usually says so on the label.

   That's about all you'll find in a big box store, if that much.  In the professional stores, you'll find catalyzed vinyls, acrylics, and urethanes, phenolics sometimes,  amino-alkyd resin systems, and some other stuff, but I doubt you'll be wanting any of those products yet.

   HTH

   Michael R

2. 
   Gretchen | Nov 26, 2003 08:05pm | #5

   You can make your own.  Don't buy pre-made wiping varnishes, etc.Gretchen

1. 
   BG | Nov 27, 2003 12:54am | #6

   Gretchen,

   Your right !  Like Jim, I am so tired of walking into Woodcraft or Rockler and feel like I'm brain dead.  I stand there looking at the Tried and true, Behlens Rock Hard, Watco, Arm-a-Seal, Waterlox and various schellacs.  If you ask the staff...their knowldegable...however, they are anxious to share a new technique they just learned over at NBSS....or, with that can of stuff you'll want this other $40 worth of products...and a $30 badger brush...again.

   It just seems to me the smarter approach is to get back to basics and make your own....document your process...and then you own it.  I started reading an old book on finishing last night...gonna give it a shot....so how do I make wiping lacquer?

2. 
   TomMGTC | Nov 26, 2003 06:41pm | #4

   I have been to one of Flexner's seminars and this is a huge pet peeve of his. It is difficult to know what is in the finishes and the finish you bought last year under the same name may or may not be the same.

   Tom

   Douglasville, GA

3. 
   RW | Nov 27, 2003 07:55am | #7

   If you really want to know what's in a finish, ask for the MSDS sheet, or often if you're buying from the manufacturer (like Sherwin, rather than Home Depot) they'll have gee whiz sheets on all their stuff. Ask and they'll print you out pages of stuff you didn't know to ask about. Those can be valuable gouge when deciding on application techniques with a new product or trying to decide if A+B=headache.

   Last thought, often the paint stores have reps who (supposedly) know the ins and outs of the product line. The better of these reps got that knowlege not from a class but from using the stuff for years until their backs gave out and they sought a simpler life. I have to give props to Bob, my Sherwin rep. Darn if he isn't just a walking encylopedia of hands on knowlege. Getting to know those types opens up worlds of other ideas. I can't count the times he's saved me aggravation. I used to think I knew finishing, when I knew how to finish furniture. Then I started doing my own work in remodels. Man, there is a whole other world out there. A lot of it is just downright fun.

   "The child is grown / The dream is gone / And I have become / Comfortably numb "      lyrics by Roger Waters

1. 
   JBD | Dec 05, 2003 06:08am | #8

   I agree with the fun RW.  Thats why I became a hi-build coatings chemist for 100% solids UV curable coatings.  Imagine laying down 10 mils on fiddleback Makore, running it under the flatline UV curing chamber, and less than ten seconds later you are sanding it to powder at almost the full 10 mils thick, just to lay on another ten mils, sand, then flood 20 mils as a topcoat that submerges all trash, then it flows out like glass, and you "freeze" it with the final cure that looks like four days of coating and a whole day fo buffing in only a half hour.

   We had access to the best raw materials from BASF, Henkel, UCB Radcure, Sartomer and scores of others for additives and such, but it comes down to cost.  The best raw urethanes will never make it into even the best hi cost 2K urethanes.  You and me would never pay 100 bucks a gallon. 

   Listen to the reps.  If you're serious, they'll steer you into good coatings if your willing to pay for it.

1. 
   RW | Dec 05, 2003 06:19am | #9

   Now THAT sounds cool.

   Had a bud I worked with while in the AF. I asked him when we were new arrivals where he came from and what he did. He said he was a coatings chemist. Huh? I said, "what, like paint?" Yup. Paint was his specialty. I was a little confused, thinking for a moment that some general had a Captain as his interior decorator. But no, he explained in his Michigan UP vocab- "well, ya know them planes get up there and go mach whatever and you get the friction, see, and them nose cones and other parts heat up and most paints don't hold up so well when you make them 2600 F. "

   Oh. Man did I plug his brain the whole time we worked together. Good combo. He didnt have the foggiest how to use a brush or a sprayer, but if you wanted to know what makes urethane or anything else do what it does, he was the man. We learned from each other."The child is grown / The dream is gone / And I have become / Comfortably numb "      lyrics by Roger Waters

1. 
   JBD | Dec 05, 2003 07:29am | #10

   Well, RW and all others who want a definition of COOL:

   Imagine a $12,000 UV lamp that produces 600 watts per INCH on a ten inch bulb of iron/gallium doped sealed quartz envelope.  Thats 6000 watts of radiation focussed onto your coating that cures by its radiation wherein if you simply passed your hand under the light, you'd feel no heat because Fusion¯ UV lamps have a patented system of twin magnetos that actually microwave the mercury/iron/gallium metals in the electrodeless bulb into a plasma state to emit intense UV radiation without the heat of infrared, and require 5 lbs of air pressure to blast past the bulb to keep the quartz from melting beyond 900° CELSIUS, thus scrubbing off the heat, keeping a cool surface temp. 

   But your hand would turn red and the skin would peel off within hours as if you were in Nagasaki at the end of WWII.

   Now imagine a chamber with 30 of these lamps, each requiring 480 volts for ignition. 

   That was my workplace.

   That doesn't even compare to the molecular storm that occurs when the UV triggers the catalytic reaction within a few mils of coatings.  You ever add too much hardener to bondo or epoxy and let it sit too long in the heat?  It'll burn the cup its in and smoke like a chimney.  And that occurs over a period of time during the reaction.

   Imagine polymerization that radical occuring within milliseconds.  I've sent 40 mil film builds in the UV laminating adhesive I formulated for laminating glass, and sent the sheet through the lights at 5 fpm and the glass was too hot to touch immediately afterward due to this very reaction. 

   We had a blast formulating super reactive impossible formulas with pentafunctional monomers (higher functionality=higher crosslinking=higher exotherm) loaded with intentionally high photoinitiator levels just to see the poured film explode after going through the lights. 

   Another cool aspect of UV coatings is that a typical coating, once cured, is completely insoluble - i.e., acids won't touch it, MEK won't dull it, acetone won't melt it.

   Needless to say, UV chemistry isn't making its way to home depot any time soon - even if cost were lower than shellac, its processing window too narrow and the lights prohibit use.

   See http://www.johnblazydesigns.com for what I did with my polymer science patents