mellow63

which is better to put on a table top? Is poly harder than lacquer?
Thank you!

skymaster

Yes poly is harder than lac. Go with water based poly if you can.

PK.

If you just want tougher, then good poly. I'm partial to Target's 9000. If you want toughness without a thick build, then use conversion varnish. If you want something with a high gloss and high build but is easy to fix, then use lacquer.

As to what's best, you first have to decide the usage of the table and what sort of look you're after. For instance I build occasional tables quite often. They're primarily designed to display the wood used and maybe a small piece of art or something. The finish used on these is primarily shellac and wax. This is a simple finish that really displays fine wood well and is very warm. I don't expect them to be used heavily but if they get marked up, it's easy to fix.

My shop primarily turned out kitchen and bath cabinets until very recently. On these I used either poly or conversion varnish for the most part because they do a good job of showing off the wood and they do an excellent job at protecting that wood. When I do a kitchen table, I use the same for the same reason. If it's a dining table, then it's likely I'd use lacquer because it's easier to build and level than poly or cv.

JCCLARK

Pre-catalyzed lacquer is more durable than all of them.
And conversion varnish is even one step higher than that.

Go here, the pro's usually don't use regular lacquer or poly.

http://www.woodweb.com/cgi-bin/forums/finishing.pl

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Jim

edp

you establish the performance requirements of your projects finish. For dresser tops and dining tables, I find that lacquer, pre-catalyzed or not, will not stand up to the use these items will see. A typical problem with dresser tops finished with lacquer is damage caused by the alcohol in cologns, after shaves and perfumes. It causes cloudy spots in the finish that can be repaired but seldom are. Dining tables finished with lacquer will not fare well with hot serving dishes. The heat, even buffered by a mat, will soften the finish causing areas of diminished gloss. Again, the damage is easy enough to fix but seldom is. In my experience, these two surfaces require the protection provided by polyurethane. Clearly, the balance of the unit can be coated with lacquer without any compromise in the overall appearance. At least, that's how it is done in my shop.

Ed

edp

I can't speak with any experience concerning conversion varnish as I have never used it but I will readily argue that pre-catalyzed lacquer IS NOT a more durable finish coat than polyurethane. My intuition leads me to believe the same about varnish.
Pre-catalyzed lacquer is a great benefit to the woodworking community in that it causes the lacquer to achieve it's full cure characteristics much sooner than standard lacquer. However, it is only achieving them quicker, they are not being improved or increased.

Ed

Corndog

I use pre-cat lacquer as a clear coat on my guitars but I wouldn't consider it for furniture. Too many variables....

cabinetman

Gee whiz Ed, holy macrimony, calm down, you don't have to shout. I will agree with your take on lacquer. But first we must look at exactly what we're talking about. I've tried just about every type of finish, both spray, wipe on, brush on, and I can only speak from my own experience.

For a simple explanation of lacquer, the pre-catalyzed is considered catalyzed at the factory, so the can you buy doesn't have to have any catalyst added. Catalyzed, or post-catalyzed is the lacquer that needs the catalyst to be added. Basically the major differences lie in the use time and shelf life.

So, now that we have distinguished the terminology, many on the forum get those two mixed up. The durability factor of a finish depends on many factors. Of the choices, not in any particular order:

Lacquer (both pre-cat & post-cat)
Polyester Lacquer
Varnish
Conversion varnish
Oil base polyurethane
Water based polyurethane
Shellac
Oils
Wax

I may have left out something, so I apologize. Each has its own properties and whichever one is selected, should be tested or used with compatible surface preparations, such as stains, dyes, tints, fillers, and sealers. Testing for durability will not give a standard answer because the applications may differ in many ways as to use. But generally speaking the order of durability for conversion varnish is higher than lacquer. On a general scale of use, oil base polyurethane exceeds conversion varnish. For some uses, waterbased polyurethane ranks as high as oil base polyurethane for some uses.

Lacquer isn't a preference for floor finishes, whereas for a long time oil base polyurethane was the choice. Nitrocellulose lacquer is an easy durable finish in a lot of circumstances. Polyester lacquer exceeds the realm of either nitrocellulose or acrylic lacquer for hardness and durability. The advances in crosslinked waterbased polyurethane has produced an extremely durable finish. It is becoming a very popular finish for flooring and furniture. Shellac, although one of the oldest used of finishes provides a good surface, is easy to use, but not as durable as oil based polyurethane.

Considerations for the choice of finish may include the steps in application, ease of use, dry time, touch up/restore capabilities, type of chemical resistance, shelf life, and compatibility to whatever may be undercoated.

Other factors on choosing a finish may include the extended life of the build of the finish and how well it will fare in its thickness. There are other factors in choosing a finish for durability, as the furniture/wood industry has its priorities for finishes, and uses electrostatic processes, whereas, the woodworking shop/cabinet shop/ DIY'er/hobbyist will have changing demands for use. Fortunately we have many choices, and that's what makes the world go 'round.

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Corndog

Just curious...I use rattle cans 'cause my parts are so small.
Do you spray or brush??? What about the environmental issues??? Safety issues???

TexasTimbers

Nice explanantion cab'man.

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edp

No shouting going on here. It just always catches my attention when people (myself included) speak with authority on subjects they are obviously still learning. When that takes place, we all have a responsibility to speak out.

As to the sequence for choosing the correct finish for the specific application. I make the first cut based on the type of use or abuse the item will normally see. Second is the ease of application for the qualified finish systems. I paint commercially 40 hours a week applying solvent based and water based catalyzed wet sprays using HVLP equipment as well as electrostatic powder coating so I have learned to identify the important attributes expected from a finish in the above order. In that way, I satisfy the client long term without working any harder than is required.

Ed

cusingeorge

Precat lacquers dry mostly by solvent evaporation, yet some cross-linking occurs to aid in moisture resistance. Polyurethane dries in much the same way but the nature of the resin system is more like a two component coating; it needs something to make it dry, and in this case, air movement makes the resins oxidize but for the faster-drying systems, they use a metal drier like cobalt to force the resin to oxidize (dry).

I would never use precat on a horizontal surface under any circumstances. Polyurethane is far more flexible and resilient to impact and heat. There are better coatings than polyurethane out there, but as performance increases, so does the difficulty in use.

TexasTimbers

cg,

What would be your choice/s for a wide plank walnut floor in a residential application that was going to be installed in a kitchen and the heavy traffic area that leads into the great room? It will have a throw rug in one small area but most all of it will get plenty of traffic.

We are considering not putting it in the kitchen but with the finishes available today we figured there would be something durable and resistant enough to the occassional spill it would be okay. What are your thoughts on this.

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daryl in nanoose

This thread has been a very good read.
So could someone please explain exactly how to apply poly. Every time I do I get a rough surface
Oh and how many coats are recommended on furniture pieces ( dressers, and so on)

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Corndog

This is pretty informative...

http://www.woodworkingonline.com/category/podcast/

edp

I spray it. Believe me when I tell you that, once you try spraying, you will never go back to brushing.

As to the rough surface with your poly, you are not shaking the can are you? This introduces bits of moisture to the poly resin and causes little cured nuggets to form. Likewise with fast stirring with a drill, only worse. If that is not it, perhaps you are experiencing a grain raise which can happen with any wet finish applied to wood. The fix is to lighly sand until smooth and then reapply the finish. The wood will be sealed so it should stay smooth for you.

As to how many coats, I always use two coats for polyurethane and 3 to 6 coats for lacquer (my favorite finish) depending on how much I have thinned it to accomodate the temperature.

Ed

daryl in nanoose

I know not to shake or stir fast, I have even let stand in the can after light stirring for about 10-20 min. Sometimes I have used a prestain and sometimes not. I am starting to think maybe I have to clean them better than I have in the past but I still get it after even the second coat. I do know how to spray so I might try that next.
This is the one cabinet I had problems with. It took four coats to make it smooth.

Attached Images

 

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JCCLARK

http://www.thewoodworksinc.com/HTM_F...ishes_Poly.htm

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Jim

cusingeorge

I hope you were asking me that question (cg=cusingeorge?).

Since it's walnut, I would want the product that resists UV radiation and is pretty clear.

In any case, there are plenty of great polyurethanes available for flooring, I would probably look at the waterbase, the technology has progressed quite a bit in the last 10 years (and they don't smell bad).

I don't make one (waterborne poly) myself, but if you "google" floor finish, you will find a host of sites dedicated to the product.

There are those who say that conversion varnish can be used, never had the opportunity to try this, but if clairity and fast dry is important, this is probably the way to go.

TexasTimbers

Yes cg = cusinegeorge, and thanks for the reply. I hadn't considered a water based poly because I have a cedar chest i finished with it around 92 that did not protect against UV over the years. But that was 15 years ago and as you say big strides have been made after that.

I also read on a forum somewhere, and I know you can read anything, but I read where a pro floor finisher had written that poly was usually the first choice but that there was something much better in every category. I bookmarked that thread but had a hard drive crash since then. I doubt there is any way oi could find it.

Anyhow that's why i ask because I keep thinking if I hear it again it will ring a bell. He said it was hands down superior to poly and that poly was a distant second in a flooring application for durability, ease of application, and something else I thing he said looks too. I wish I could remember what he said. I will llook into the new waterbased polys though.

Thanks for the reply.

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When our outgo exceeds our income, then our upkeep becomes our downfall.
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