Hello all,
I am getting ready to build a coffee table for my family room. I am planning on building it out of Walnut to match our entertainment center. However, my family and I would like a very strong and durable finish on it. The current “cheap” coffee table we have now “clouds” and leaves white rings from hot plates being set on it or from a wet glass.
I am asking for suggestions on a finish that will take the abuse from a busy family. I have heard that Water-Based Polyurethane will cloud, is this true?
Cheers!
darkmagneto
Replies
In my experience, no polyurethane, water based or solvent based will cloud. The traditional solvent based ones are stronger, although improvements have been made in the durability of water based ones in the last few years.Either way,they're durable. Two part clear epoxy is the only other more durable finish if you take the DIY approach.
Water based polyurethane is cloudy (milky) when it is in the can, but clears shortly after it is applied.
My preference for coffee tables (and most furniture) is lacquer, if you can spray it on. Polyurethane is a little harder, so cannot be rubbed out as well. A film finish (where each layer dries) is far more difficult to repair than a solvent finish (lacquer or shellac) where each layer "melts" into the previous.
Lacquer provides easy application, fast drying, durable, repairable, and rubbable (to perfect the surface and determine the degree of gloss).
________________________
Charlie Plesums Austin, Texas
http://www.plesums.com/wood
DM,
"Bar Top" varnish is what you want. As its name implies, it is made for applications like yours.
Bar Top is an alkyd based varnish, so you avoid the plastic look and greenish cast of poly. (I don't like poly. I don't doubt it's better now than it was when I acquired my dislike of it; but IMHO it still looks too plastic-like and still has a greenish tinge to it.) Four or five coats, properly rubbed out to whatever final sheen you want, and you'll have a stunning looking finish that enhances the color of walnut, and provides excellent protection.
Alan
My favorite table finish is Minwax Helmsman polyurethane, satin finish. About 3 or 4 coats would be good. Thin the first and last coats a little bit. Polyurethane is about the most scratch resistant finish you can choose.
I've never seen polyurethane turn green.
Waynel5,
No one said it turns green. What I said was that it has a greenish cast, or tinge to it. In other words, if you put a coat of poly on a piece of white paper, the paper would have a slight greenish tinge.
A couple of points about semi-gloss or satin varnishes-=poly or alkyd. Back in the olden days it was explained to me that the flattening agent in varnish, the substance that makes it satin or semi-gloss, makes the resulting finish a bit softer. I'm told that's no longer the case. The current additive is a substance that, in effect, "clouds" the varnish a bit, makes it more opaque, so it doesn't reflect as much light (I'm repeating as best I can remember the explanation given by someone else). The point is that the effect is additive; that is, each succeeding coat adds to the opaque effect, and further obscures the grain and texture of the wood. The fix given by the one who explained this is to use gloss for the first coats and use satin for only the last coat.
Second, is that varnish needs to be rubbed out. Both varieties of varnish attract nits and bits and motes like Tokyo attracts monsters. (Again I'm told that poly reduces this a bit; I can't remember the reason.) Add to that, it is very difficult to brush on a surface that's perfectly flat. All this means that varnish--alkyd or poly--needs to be rubbed out.
To rub out a finish you begin with wet sanding and then move up to ever finer abrasives. You stop when you get to the gloss you desire. So putting on a coat of satin is unnecessary. Begin and end with gloss varnish--it's harder and has none of the agents that obscure the wood.
Alan
Thanks for the information. I've used as many as six coats on a zebrawood veneer and oak bar top and it didn't cloud or darken excessively, nor diminish the chatoyancy of the zebrawood. But I'm always looking to learn more about finishing and make the finish come out better. Your information is helpful.
Waynel5,
I'm happy you found my post useful--even though I can't remember most of what I was told about poly varnishes. If you care to get a fuller and more cogent explanation you might want to search the archives; I'm sure I was enlightened on this site.
About not seeing the difference in your zebrawood and oak, I think you would not unless you're specifically looking for it. A little like the frog in the pot of water, each succeeding coat will add just a bit more of the opaque stuff. I think it would be difficult to see the difference between coats. A better test would be to finish one piece of zebrawood, or whatever wood you have around, with one coat of gloss, and finish another piece with your usual number of coats of satin, and then see if a difference is apparent. If you try this please post your results. I'm always anxious to learn.
I should have mentioned that I tried a poly varnish four or five or so years ago. As I remember it was Heirloom brand--if there is such a brand (more senior moments). As I recall, I put three coats on a piece of white foam-core. To my eye it still had a greenish tinge (this was before all my current eye troubles). Try this too. It would be interesting to find out whether I was, in fact, seeing what I expected to see.
Alan (again going on too long)
Alan,
I have a TON of Walnut scraps that I was going to practice on. I will put ALL the scraps through the "heat" and "glass full of condensation" test.
One quick question about using the Poly. You would "rub it out" after several coats? So wet sanding and then move up to steel wool? I am not too familiar with rubbing out a finish. Can you help me with that?
Cheers!darkmagneto
I am using the Helmsman oil based poly spar varnish on a coffee table now.
I wiped each coat 50% varnish / 50% mineral spirits on with a paper towel and wet sanded 400 grit / mineral spirits every second or third coat. My 6th coat went on today. That should finish it. I will rub out any rough spots with 1000 grit / mineral spirits and then pumice and rottenstone.
Dark M,
Rubbing out is very simple to do, but requires some patience.
First you flatten the surface. I use wet and dry paper on one of those rubber sanding blocks, that's lubricated with water that has a drop or two of soap in it. I begin with 400 grit paper, and repeat the same steps with 600 grit. I usually rub in little circles, around the edges and then in the middle. Easy does it; it's too easy to sand through on the edges.
I next use 0000 steel wool, or the plastic equivalent, lubricated with wool lube. Some use water and soap as a lubricant, but IME wool lube is more viscous, and hence lubricates better. IMHO it's worth the trouble to find wool lube. First time around I use the same pattern as with the sand paper. Second time with the wool I use long strokes with the grain. I also lighten up on the second go-round, telling myself that I'm now polishing the wood.
I often stop after rubbing out with the steel wool. That generally leaves a finish that's close to a "satin" varnish. To bump the finish up to semi-gloss I use my own concoction of wax.
To go to a higher gloss I use pumice and then rottenstone lubricated with paraffin oil (it's worth it to find paraffin oil too). With the pumice I again rub with the grain, but with rottenstone I go in little circles. Properly done, a finish rubbed out with rottenstone will have a high gloss, but without the plastic look and feel of gloss varnish out of the can.
IMHO a rubbed out finish is much more attractive than one which has not. It looks more like the finish is in the wood rather than on it. It will have none of the plastic look or feel to it; the surface has that silky-smooth surface that feels so nice to touch.
One warning. Don't try this with spar varnish. Because it's meant to be used on exterior wood, spar varnish is formulated so it remains soft--so the wood beneath it can move with humidity changes without cracking the varnish (it also has UV filters which are of no concern). Even after it's completely cured you can peel up spar varnish with a fingernail. Because it is so soft it's more difficult to rub out than a good interior varnish. I know some people swear by spar varnish; but I wonder if they would use it if it was instead labeled "exterior" varnish.
Alan
Good explanations, Alan. The flatting agents you were curious about are actually powdered glass (fumed silica). Some are wax treated to aid in surface cure and feel which adds to the opacity you reference (I'm a former finish chemist). In thin coats, you won't notice the opacity, but you've given good advice on clear build coats, then top coat satin.
Ditto also on exterior poly - too soft. Spar even softer. Remember - this is a coffee table here.
If you ever rub out to gloss, I suggest automotive systems - easier, faster. Wet sand starting at 800 then 1200, then rubbing compound, then final glaze (swirl mark remover) for insane gloss. I often start at 1000 grit, cuz anything coarser actually creates deep scratches. If you have a sag or big nerd, I cross-scrape with a razor, then hit with 1200, then buff.
Real important to let the finish dry for as long as you can bear to wait - the more you wait (months), the better a rubbed finish will retain its glass-flatness. Over time, additional crosslinking and off-gassing of entrapped, unreacted monomers will continue to make the film shrink and this will telegragh the pores of the wood if you rub-out as soon as the film dries. Best to leave the finish in the sun or in a heated room for a few days, or weeks before buffing final.
"The furniture designer is an architect." - Maurice DuFrenes (French Art Deco furniture designer, contemporary of Ruhlmann)
http://www.pbase.com/dr_dichro http://www.johnblazydesigns.com
"Real important to let the finish dry for as long as you can bear to wait "
In my opinion, even more important to let the filler dry for as long as you can stand it. Often much thicker in the pores than the actual finish. Wait before final sanding or the pores will telegraph no matter what you do with the finish. Unless you fill with a reactive filler like epoxy or polyester. Some fillers will also expand a bit after you apply sealer or first coat of finish, depending. Likewise, wait until it shrinks back.
Excellent point Bob. This is why I like to use epoxy as a filler for porous wood that I intend to rub out. Epoxy shrinks a little less than polyester, but PE is certainly better than solvent based fillers. FYI - The swell you experience with some fillers is due to solvents in the sealer. PE and epoxy won't accept solvent penetration.
"The furniture designer is an architect." - Maurice DuFrenes (French Art Deco furniture designer, contemporary of Ruhlmann)
http://www.pbase.com/dr_dichro http://www.johnblazydesigns.com
I've gone to epoxy for some things myself. French polish is one of the worst offenders. People say you can fill and polish in 2 days. Sure, if you want to see grain in a month. If you want a true mirror finish that stays smooth, you have to use a modern filler or wait a long time. I have yet to find one I really like. Epoxy isn't too bad except for the smell and it doesn't sand real well. I do worry about long-term effects with it though. Has not been around long enough to really know what it will do in 50 years. The actual finish is not a big problem. Even if a .010 film shrinks down by half its not a problem if the surface stays flat. But, if you have .010 or .020 in the grain and that shrinks a little after the finish is on top, its highly visible.
Hey Bob, here's some info you might like from my many years and gallons of epoxy use:
"Epoxy isn't too bad except for the smell (what smell?- not near like PE) and it doesn't sand real well (I have never had trouble sanding it - gotta be well cured though). I do worry about long-term effects with it though (epoxy is one of the safest polymers ever due to the fact that it is so thoroughly cured to be near inert. Some can be sensitized to the hardeners, but just don't bathe in it. No fumes or solvents. Big Box polyurethane is more dangerous - trust me, I'm a chemist with patents in polymer science). Has not been around long enough to really know what it will do in 50 years" West System has been making boats in epoxy since the sixties. No health problems that I ever heard. The biggest health problem is sanding through the epoxy into the fiberglass (if you build boats).
Click on my links below and see the mahogony boat I built in epoxy. The foredeck is ribbon stripe mahogony with West System sealer/filler, then a spar urethane topcoat wet sanded and buffed like glass. Long lasting gloss too. The epoxy really keeps the grain from telegraphing too.
"The furniture designer is an architect." - Maurice DuFrenes (French Art Deco furniture designer, contemporary of Ruhlmann)
http://www.pbase.com/dr_dichro http://www.johnblazydesigns.com
I use 30 minute or 3-hour cure stuff that comes in 8-ounce squeeze bottles. 1:1 mix. It does not smell great and only sands tolerably well if wet sanded with odorless thinner, but poorly otherwise. I'd rather not be soaking in thinner quite so much. I'm sensitized to the hardeners and rosewood and about 300 other things. Is West any better?
DrDichroic,
I'm glad you and others filled in information I intentionally omitted. I was trying to go easy on someone so early in his wood working experience. I didn't want to scare him away.
I have a question. If I properly understood your post, wax is still being used as a flattening agent in some kinds of varnish. Wax is the ingredient I was told--many years ago--was the flattening agent that made varnish a bit softer. Lately someone here (I've forgotten who) wrote that present-day varnishes do not have that agent; silica is used instead of wax; and that silica doesn't soften cured varnish. Is wax still added to some varnishes? If so, which ones?
As to auto polishes, rubbing compound and polishing compound: I've tried them, but I've always gone back to pumice and rottenstone. When I tried auto polishes It took much longer to approach the gloss left by 4f pumice and rottenstone. Why, I wonder. Is this just me? or the process I use? I don't use nearly as fine sandpaper as you; I start with 400, and step up to about 600, and then use abrasive wool. Could it be that 600 or so paper leaves a surface several steps too coarse to go directly to rubbing compound? What advantages are there in using the automotive products instead of the traditional products?
TIA,
Alan
Alan,
I've been using the auto products since the early 80s, so I pretty much view them as a (very) long-established improvement. I find them much more predictable, much faster working and capable of much better results than pumice and rottenstone.
I never could get a very good final finish with rottenstone. Maybe it was my technique, but the modern polishes have worked beautifully.
VL
Wow Bob, you certainly make a good case for bad epoxy. There are fast cure epoxies that have high amine content in their hardeners, which account for the fishy smell, the clogging of sandpaper (from amine blush, or "sweat" of amines to the surface leaving a waxy film on the surface), and the sensitizing to skin. I guess I was spoiled by West System. Much lower amine content, making better smell, less blush (207 special coatings hardener has no blush), and less irritation. You'd like it better, but will take longer to cure.
Good point Alan, about being a little less technical to keep this on the lower shelf. As far as waxed flatting agents, I do not know its use in varnish. I just used them in 100% UV cured coatings as "wax treated" silica. We had a choice of many suppliers and the waxed silica gave better surface cure, but the non waxed silica was indeed "clearer" in the clear coatings. Powdered glass will disappear in clear finishes when wet out. As a matter of fact, Cab-O-Sil (fumed silica) is a thixotropic (thickener) used in all kinds of "clear" stuff like silicone sealants, all the way to shampoo (I think).
Its been so long since I used Pumice and rottenstone, that I can't remember if it really is better or not than auto compounds. One reason I thought it was better, is that they use aluminum oxide as the abrasive in the compounds, and that is known as one of the longest lasting (staying sharp) abrasives available.
You mentioned that you use abrasive wool, so are you doing mostly satin finishes? If so, then I agree with you using 400 to 600. But when I used to use 600, then 800, (much experience here) I found that I spent more time with the 1000 grit trying to get the 600 grit scratches out than I was spending time leveling the orange peel. If I used fresh 1000 grit paper, I could take down the orange peel fast enough for me, and then lightly hit it with 1200 and the compound could gloss that up well. I suppose its just personal preference, and your method could very well be as good or better.
I know one thing for sure - no matter what grit your using, even 1500, if you don't clean and irrigate well, you will easily pick up crap and put scratches into the finish (been there, screwed that). I've even created little balls of finish slurry that scratched the film. Thats part of the reason that I like to add more elbow grease in the rubbing compound stage. It removes material (power buffer) almost as fast as hand sanding 1500. This is sometimes proven in the most disappointing ways (edges).
Cheers - JB
"The furniture designer is an architect." - Maurice DuFrenes (French Art Deco furniture designer, contemporary of Ruhlmann)
http://www.pbase.com/dr_dichro http://www.johnblazydesigns.com
DrDichroic,
I don't think I do mostly satin finishes. With 0000 steel wool, or its plastic equivalent, careful rubbing out with wool lube and then waxing, I would say produces a semi-gloss surface--or possibly a tad shinier than semi-gloss.
I may be getting a higher gloss for reasons other than the abrasive I use. For example, I find using wool lube instead of soap and water bumps up the sheen quite a bit. (Why? Because it is so viscous it's a better lubricant? I really don't know.) I've also used wool lube with wet & dry paper and that seems to produce a higher sheen than the same grit paper lubricated with water and soap.
Also, I concoct my own mixture of wax from carnuba, bees wax and turpentine (and for some finishes I'll add paraffin). It is much harder than anything I've found already mixed. It also buffs out to a higher shine than any other wax I've seen. Just using my secret formula wax with energetic buffing will bump up the sheen a notch or two.
When it gets to pumice and rottenstone I usually lubricate with paraffin oil. I've tried using lemon oil--or orange oil--water and soap, wool lube and my Lilac Vegitol after shave lotion, but none of them do as well as paraffin oil (read "produced as high sheen"). And, as you pointed out, I'm not stingy with paraffin oil--or any other lubricant--so I am less troubled by contamination or more gritty slurry.
Does any of this make sense? Or am I just so old and set in my ways I'm defending the unlikely? I'm always eager to learn--and to take advantage of other's generosity in sharing what they know.
Alan
Good info Alan. I'll have to try your wax concoction - heard of it before, but never obtained one of those round things called a "tuit". Someday I'll get a round tuit.
Possibly your higher sheen experienced with the wool lube is due to some burnishing effect. Simply rubbing a surface without compound will burnish a little gloss. Good results are all you need, so more power to ya!
When you described using parrafin oil with the pumice/rottenstone mix, I realized that you were almost creating the basic formula for automotive rubbing compounds. They are fine abrasive (alum ox) in a hydrolized wax (don't know what kind). This way you can re-charge a dry pad with just a water sprits, yet still get good water beading from the wax. That is one advantage I really like about auto compounds - water soluble. Then I can simply wash down the surface with a damp cloth to remove all traces of compound, then I apply a german poly/acrylic (?) glaze called "Klasse" that all the pro car finishers swear by. I never tried to recoat it yet (yikes).
I learn from you and vise versa I guess - Cheers - JB
"The furniture designer is an architect." - Maurice DuFrenes (French Art Deco furniture designer, contemporary of Ruhlmann)
http://www.pbase.com/dr_dichro http://www.johnblazydesigns.com
3M makes a "show car" finishing wax. No silicones. The highest gloss I've found. Only needs a drop. Makes a mirror gloss if the surface is halfway decent. I also like their rubbing compounds. Go through 3 grades from rubbing compound to hand glazing. Takes over from where pumice stops. Not that I use pumice anymore. Too many larger particles. Pumice can have pieces as big as a couple thousandths before they start to break down. Had too many deep scratches. The automotive compounds are better graded. I like the squeeze bottles. Less chance of getting a stray piece of grit which can happen if you dip a pad into a tub of rubbing compound.
DrDichroic and all others,
I come here to learn. It's great to have people who are immersed in a subject, and give away the knowledge and know-how it's taken them years to acquire. I'm grateful.
Bob,
I've not heard of the 3M products you mentioned, but I am going to try them (on experimental samples, of course). Where might I find them?
Where do you stop with more traditional abrasives? I.e., what grade sandpaper or wool or pumice or...do you use before switching to the 3M stuff?
What do you use for the final treatment? Surely my wax recipe probably couldn't be buffed out to the ultra-high gloss you get. Is the final product a glaze like they use on fiberglass? or a wax that will hold a high-gloss? or...?
TIA
Alan
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