Aargh Polyurethane or Lacquer or Shellac or Varnish -- I'm confused

Please help,
I promised to make a table for my wife. All went well until I realized my partial gallon of High Gloss polyurethane by Deft had thickened (I assume repeated use allowed some ingredient to evaporate, guessing the metal lid is no longer properly sealed after repeated opening and pounding shut). Initially I thinned part of the can with paint thinner and this worked fine on another project (baseboard trim). On the large table surface however, I was able to see small hardened particles in the poly. Additionally the thickness made it difficult to work with and I made the mistake of allowing it to dry rather thick on one portion of the table. The result, wavy distortions of the woodgrain. So I sanded, intending to start over. When I arrived at the store, the clerk no longer sold the same product. They said I have my choice between Minwax brand CLEAR polyurethane or LACQUER or SHELLAC or VARNISH. They recommended Deft brand clear lacquer. Another store recommended CLEAR polyurethane by Minwax. I went back to the 1st store and bought clear lacquer (maybe a mistake?). After spot sanding, and applying LACQUER, the table top is again smooth. The wavy distortions are gone, but some areas of the table are shiny and some are dull. What are my options? When dry, what are the appearance and performance/endurance differneces between Lacquer, Shellac, Varnish and Polyurethane? Also what should I know about working with each? Will clear polyurethane, give me the shiny finish I wanted and previously got with the "High Gloss" polyurethane? If not can I buy Deft "High Gloss" poly through the internet?
Thanks in advance, Novice woodworker
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Just to clarify, all poylurethanes are varnish, but not all varnish is polyurethane.
Shellac is a wonderful finish that has been around hundreds of years. It is not alcohol resistant though and will dissolve in its presence. Don't spill a drink on the table if you use it. Shellac is used to coat M & M's and many pills. It is made from a secretion of the Lac beetle.
Clean poly comes in satin, semi gloss, high gloss. One of them should suit your needs.
Lacquer is nice, durable, most often sprayed, but brushing lacquer does exist.
For better info, ask over on rec.woodworking.
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Edwin Pawlowski wrote:

I agree with all of the above and will add that while I love shellac I would not choose it for a table that will see a lot of service or is likely to receive alcohol spills. Shellac is very nice to work with.
I would not suggest lacquer. It takes some skill to do right.
--
Joseph Meehan

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Joseph Meehan wrote:

I'm no laquer expert, but I have had success hand rubbing with "rottenstone" and oil. Rottenstone is a very fine abrasive. I actually used a felt pad attached to a wood sanding block, applied a bit of a light oil as a lubricant, and used liberal amounts of elbow grease. /Kinda time consuming, but the results were great!
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1_Patriotic_Guy wrote:

Simplistically...
All clear "top coat" finishes consist of two primary components: the vehicle and the resin or solid which is dissolved in the vehicle. The ones you will encounter as a consumer dry/set by evaporation of the vehicle.
The resin for varnishes is normally either alkyd or polyurethane. The vehicle is mostly paint thinner/oil (both) or water (only poly AFAIK). The water based polys dont color the wood like the oil based ones; i.e., they don't make the wood much darker or the grain/figure more apparent. Oil based varnishes will impart a slight amber coloring as well as "pop" the grain.
Lacquer is various plastics dissolved in a fast evaporating vehicle. The "plastic" used to be nitrocelluose, nowadays it can be lots of things. They are water clear but pop the grain like oil base varnishes but less so.
Shellac is a refined secretion of a beetle dissolved in alcohol. The color is determined by how refined the resin is. It can vary from dark brown to orangeish to almost clear. It is normally bought in flakes which are then dissolved in alcohol as needed. _________________
Poly varnish = hard but "plasticky looking. Takes a long time to dry (up to a month for complete dry). Should be sanded between coats. Hard to repair.
Alkyd varnish = not as hard but better looking IMO. Takes a long time to dry too. Should be sanded between coats, sands easier than poly. Hard to repair.
Lacquer is probably the most used commercial finish. Since it dries rapidly, several coats can be applied in a day. There are varieties for both spraying and brushing. Complete drying is several days depending on how thick/many layers there are. Doesn't have to be sanded for adhesion, one coat melts into the next. Normally sands easily. Can be very hard, can be relatively soft...normally about like alkyd varnish. Very easy to repair.
Shellac is like lacquer in as much as it dries rapidly and sands easily but doesn't require sanding between coats. The coats are very thin and it takes many to build a nice finish. When done properly by someone who knows how, it gives a beautiful finish...often used on musical instruments including pianos. Very easy to repair.
It also makes a good "barrier" coat because it can be applied to any other clear finish and any other clear top finish can be applied to it. You cannot apply lacquer to varnish (vehicle eats the varnish) but you can do vice versa. ____________________
The sheen of any clear finish as it comes from the can is able to be varied. All are normally glossy. If a flatting agent (often powdered talc) has been added it diminishes the shine. Add more and it is diminished more. Same effect can be achieved with mechanical abrasion...0000 steel wool, pumice, rotten stone, rubbing compound, etc.
The best high gloss finishes aren't "out of the can"...they are worked up by rubbing out with finer and finer materials. That not only gives a glossy finish, it gives a smooth, flat one. ______________________
IMO the best/easiest clear finish for home projects is brushing lacquer...it is easy to work with and builds rapidly. It is very easy to repair too. The one I particularly like is Deft Clear. Unfortunately, the can says nothing about it *being* lacquer but it is (you can tell by the smell). Comes in glossy and semi gloss.
-- dadiOH ____________________________
dadiOH's dandies v3.06... ...a help file of info about MP3s, recording from LP/cassette and tips & tricks on this and that. Get it at http://mysite.verizon.net/xico
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The poly didnt cure before the laquer, there is a chemical reaction that is why you have gloss areas. It could take months to cure the poly but since you now have laquer wait a few weeks then try laquer again. Mixing products is never a good idea in finishing when they are new. You are lucky it could have pulled up the poly.
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Deft makes brushing lacquer that has GREAT self leveling attributes. Would work well for a tabletop as it's horizontal. Check label for material used to cleanup.
On Wed, 23 Feb 2005 23:01:32 GMT, "1_Patriotic_Guy"

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