What is the difference between shellac, lacquer, polyurethane, and spar urethane?

Shellac is as has been said made from the larvae of an insect dissolved in alcohol. It is used both as a furniture finish (and a very good one) and sealer (both for furniture and covering spots that you think might bleed through paint). It comes in three varieties, white, orange, and pigmented. White is what most people use and unless the can says it is ready to put on, you may want to thin it to a watery consistency. It dried fast and thus avoids gathering all of the dust and bugs that are close by.

You can use clear, white or orange, shellac as a sealer depending upon the final color you are looking for. The white pigmented shellac is use for sealing like on walls where there are spots or even on bleeding knots.

It is thinned with alcohol which can be listed as Shellac Thinner or Denatured Alcohol.

Don't buy more shellac than you have to use in a short time. It will spoil in the can and if you open a can of spoiled shellac, it will smell to high heaven and because of the gasses formed inside of the can, it can actually explode on you - not a fiery explosion, but certainly something you don't want.

Shellac only comes in a gloss. If you want it flattened, or satin finish, use 0000 steel wool and rub it out.

Lacquer is a nitrocellulose product and is thinned with lacquer thinner. It is used for furniture finishes as well as some metals. It used to be used on automobiles. Like Shellac, it is hard. It dried rapidly. It is available in a brushing lacquer and a spraying lacquer. Lacquer can "blush" when brushed or sprayed. That means that it will take on a whitish appearance, but that can be stopped two ways:

Spray some more clear lacquer thinner on top of it, preferably having some retarder in it, or use retarder in the lacquer when you spray it. Lacquer dries very fast and the blushing is caused by the outer surface drying faster than the rest of the finish.

There are non-polyurethane finishes in Varnish but you seldom see them any more. You will be selling Min-Wax, but I would not use that on the inside of my garbage can. I simply don't like it. That is me, however, and the housewife who is refinishing an old piece of furniture will ask for Min-Wax. Make her happy and sell it to her.

Polyurethanes came onto the market in the late 1950s or early 1960s. It is an incredibly hard finish and is available, like lacquer, in flat, satin and gloss finishes. There are water soluble polys that I would now sell over the regular ones because they dry faster. Regular polys take at least 8 hours to dry, thus gathering all of the bugs and dust that will be available during that time. For someone who does not know how to use lacquer, either brushing or spray, sell them water based poly. Spar varnish is supposed to be use when a heavier duty varnish is required. It gets its name from varnishing the spars on a boat or ship. I doubt if you have a non poly spar urethane, but I would not use the Min Wax product outside at all. It does not weather well.

Actually Varnish is a collective term and includes shellac, varnishes as we know them today, paints, and lacquers.

Frankly, I buy shakey old furniture and rebuild it. You can't get good furniture today, so I get stuff made in the late 19th century up to about 1930 or so. To finish, I almost always spray a gloss lacquer and de-gloss it to my liking with 0000 steel wool. I have only been doing this for about 50 years and my finishes last since I am still using most of what I did 40-50 years ago. I could be enticed to use a water based poly and may well use it on something I am doing right now, but that is mainly because my shop is in the drive way now and it takes too long to get the compressor out.

Shellac Vs Polyurethane

Spar Urethane Vs Polyurethane

Shellac is a resin secreted by the Lac Bug from South South Asia. The resin is mixed with Alcohol.

Lacquer is Shellac using a solvent rather then alcohol and should have a higher flash point.

Spar urethane & Polyurethane are similar plastic resins carried in water or solvent. Spar is made so it can be use outdoors and won't yellow as much. Poly is an interior product that usually has better wear tendencies.

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Simple, a sparring partner is someone that trains with you for the mutual benefit and improvement of both of you. Should a sparring partner be less skilled, of equal skill, or of greater skill. I think that you should experience all three. Working with someone that is better than you pushes you to improve in ways the others might not. But if you always get overcome by the greater skill, it may have a negative influence on your mental view of yourself. Sparring someone that is less skilled is many times a bad influence on you too. It may lead you to not train harder, to get a big head, or to think you are better than you really are. Yet it is good in that you do see the difference in your skill vs. someone that is much less skilled. And it allows the sparring partner to test and improve his skills. An opponent is very different from a sparring partner. An opponent is someone that is out to best you. He may be someone that does not care if he injures you. He is out only to win. He may be trying to show off. In no way is an opponent trying to help you better yourself. Sparring without supervision is something that only mature Adults that are highly skilled should do. Those with less skill and self control are asking for trouble. Many students of martial arts tend to spar with their friends a lot. Many times this ends up with one or two thinking that they are better than they are. Their lack of more and more skilled sparring partners/opponents keeps them in a small limited environment. It often leads to the individual having a very distorted self image of their abilities. ...

I'm not surprised the company has not attempted to train their sales staff . I run into that problem all the time at Home Depot.

I can not easily answer your question. I once needed to learn the same thing and spent a lot of time using my search engine to collect and print off that data. It is a complex question to answer and my best advice is to grab your Yahoo or Google and start.

The answer is not possible in just a few paragraphs.

shellac is alcohol base,lacquer is lacquer thinner base.poly and ureth,is paint thinner base.(turpentine)base.