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Thread: Satin Spar Varnish vs Fast-Dry Polyurethane????

  1. #16
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    (Badger?!! At first I felt sorry for the Badger but then I remembered from my childhood how a nasty Badger went after our family dog!!)
    LOL!
    The "badger" moniker refers to the style/makeup of the brush/bristles, not the actual hair of the critter.

  2. #17
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    There are actual brushes made from the hair of the Badger. But you will only find them in certain artists styles, (and shaving brushes) at SERIOUS prices. They dye China bristle to have the badger look, and these are usually fairly decent brushes. But, for varnish I much prefer china bristle with a healthy admixture of ox hair. Still reasonable. I am often so glad to be done with a varnish job that I'm not real good at brush cleaning, so the really high end brushes which might be really nice are not going to be used by me. Mostly, proper thinning will make all sorts of varnish brushes provide excellent results.

  3. #18
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    I just spent several hours refreshing my research on varnishes and all I can say is, Holy Smoke, what a witches brew of various concoctions. We think we know something about the product we are buying? Wrong, we haven't the slightest idea of what we've getting because they don't tell us beyond the advertising claims. Varnishes are made with such a large number of base materials and processes that result varying qualities from manufacturer to manufacturer. There are no standards and no consistency. Poly varnishes are simply polymerized and can be almost anything, usually not alkyds which are derived from vegetable oils, but are hybrids. By their very nature, polys have to have a higher solvent content to maintain lower viscosity, which is why they result in thinner coatings.

    Another point, we do not know whether we are getting an alkyd or resin based product unless it says so on the can and none of mine do, so what I really got there is a mystery. One brand simply says "Solvent based varnish". WTF does that mean? Not a thing. The coatings industry gets away with murder so far as product disclosure is concerned.

    Despite all that, the damn stuff performs pretty well.
    Last edited by Harvey Pascoe; 06-26-2011 at 8:12 AM.

  4. #19
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    Poly varnishes are not simply polymerized--they contain some amount of polyurethane resin, in single part varnishes almost always modifying alkyd resin. There just isn't any reason for poly varnishes to contain more thinner (not solvent). If there is a reason I'd bet it is mostly economic, thinner is cheaper than resin, and single part polyurethane varnishes typically aim for a lower price segment of the market. If a varnish doesn't state the resin you can pretty much assume it is alkyd. The other basic choice is phenolic resin, and the varnishes that contain that tell us--ie. Waterlox and Behlen Rockhard. You can also pretty much assume that the oil used as an ingredient is linseed oil, unless you are told otherwise, like Waterlox touts it's tung oil, and Pratt & Lambert it's Soya oil. Sure on the specialty fringes there are other oils and resins, but that's of little relevance to those of us who by finishes from retail sources.

  5. #20
    Quote Originally Posted by Harvey Rabbett View Post
    By their very nature, polys have to have a higher solvent content to maintain lower viscosity, which is why they result in thinner coatings
    Harvey, I'm curious where you got this information. I didn't have the same understanding. In fact, I was under the impression that for VOC and hazmat shipping reasons, retail polyurethane has actually gotten thicker in recent years.

  6. #21
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    I was going to ask the same question Prushun asked. I'm finding that most varnishes for the DIY are coming with lower and lower VOC numbers thus LESS thinner. Many are too thick to brush properly without thinning.

    In reality we are not talkng about resin and solvent here we are talking about VARNISH (made from resin and one of a few oils) there is no oil, no resin left. Just the new by-product made by cooking the ingedients it's VARNISH.

    Varnish isTHINNED with mineral spirits (MS) the thinner is this can is NOT the solvent.
    Last edited by Scott Holmes; 06-27-2011 at 1:42 PM. Reason: typo
    Scott

    Finishing is an 'Art & a Science'. Actually, it is a process. You must understand the properties and tendencies of the finish you are using. You must know the proper steps and techniques, then you must execute them properly.

  7. #22
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    Have you ever compared the viscosity of say, Miniwax poly with that of any generic alkyd? The later is double that of Minwax. Can you think of any reason why this might be so other than solvent content? I can't. I have film gauges and Minwax cures 1/3rd thinner than alkd and four times thinner than spar.

    I got my info from a PDF file found on the 'net written by a polymer chemist about three years ago. I tried to relocate that document but couldn't. Like everything else, we can either assume that what we read is correct or not. I usually judge by the qualifications of the writer, and this one had some. The writer stated that the contents of poly urethane varnish are polimerized and the molecular chains are merely similiar to that of urethane, but are NOT urethane which is a thermoset plastic whereas varnish cures by oxidation and evaporation of solvents.

    Mineral spirits most certainly is a solvent. A solvent is defined as the ability to dissolve solids so even water is a solvent. The question is, a solvent to which solids. Resins contain solids which are the sap from trees. Solvents are used to dissolve these solids including the cellulose in lacquer. Another solvent in varnishes is ethylene glycol.

    Another myth about poly is that it can't be wet sanded and polished. I've read that in at least two articles, including one in FWW. Nonsense, I do it all the time, it just takes at least 30 days to cure before polishing but I can bring it up to a mirror finish with machine buffing. However, I don't think you'd can achieve good results with hand polishing as some do with other varnishes.
    Last edited by Harvey Pascoe; 06-27-2011 at 7:35 AM.

  8. #23
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    Harvey, I don't know where you are getting your info but you seem to have misunderstood what you are reading.

    Oil based varnishes are pretty simple compounds. They consist of a resin and a drying or partial drying oil. These two components are mixed and heated together until they combine into a new compound called varnish. This varnish is then mixed with mineral spirits to make it flow out properly and be easier to brush. There are basically three resins used. One is alkyd, another is phenolic and the last is urethane. The most often used drying oil is linseed oil but some varnishes are made with tung oil and specialty varnishes like those used on violins are made with other oils.

    "Solids" in the mixture are components that do not evaporate . The thinners all evaporate and therefor are not considered "solids". Mineral spirits, naphtha and some other chemicals are thinners, not solvents as defined and used in the manufacture and application of oil based finishes. Thinners will not melt or dissolve a dried and cured oil based finish. The solvents for oil based finishes are chemicals like toluene and methylene chloride and acetone. These chemicals will soften and dissolve dried/cured oil based finishes.

    Viscosity is a function of the amount of thinners added, not the type of resin or oil. Each manufacturer will produce their product with the viscosity they think is appropriate to their product. Using urethane (poly) resin will not in itself change the viscosity of the end product. You are correct though that "poly" varnish is not truly a urethane. True urethane coatings are manufactured as two part products. These products are frequently used in marine coating applications.

    Finally, it looks like you are confusing waterborne finishes with oil based finishes. Waterborne finishes contain ethylene glycol--oil based finishes do not. Waterborne finishes are a totally different and very complex technology containing many different chemicals. It's not just substituting water for mineral spirits..
    Last edited by Howard Acheson; 06-27-2011 at 11:59 AM.
    Howie.........

  9. #24
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    No Howard, I'm not confusing with water borne but I did mispeak about ethylene glycol. It was Valspar that used just "glycols" listed on an old can that I have. But it looks to me, after doing a few hours of research, like so-called oil-base or alkyd varnishes have just about gone the way of buggy whips. I found zero manufacturers who offer a product with those terms. VOC solvent based varnishes are being phased out. The two remaining categories are spar and poly and poly can be just about poly anything. The spars lean heavily on exterior/UV properties statements and little else. Very few mfgrs provide data sheets any more and those that do neatly avoid saying much other than dire warnings. But what little they do say suggests they are all synthetics of all sorts of polymers, including polyester of all things, and vinyl, too. Minwax and Cabot/McClosky/Valspar provide zero information. Interlux provides the most by revealing only the solids content by percentage and wet/dry film millage. Epiphanes provides nothing beyond product description. Ace Hardware has one simply labeled "solvent based varnish." Gee, no kidding! There are also single part epoxies and vinylesters.

    So, unless my research on the internet is defective, that's about it, no more natural coatings, just plastics.

  10. #25
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    Harvey, I'm not totally sure what you mean by "natural coatings"...can you help us out? There are some coatings available that might apply if I'm reading you correctly...Tried and True Varnish Oil, which is manufactured from linseed oil and tree resin which is then polymerized via heat. (I don't happen to like it, although I like their oil finishes for decorative items)

    It's absolutely true that many of the familiar oil based products are either gone, going or have changed substantially because of VOC legislation. While it's understandable that we might want to lament their passing, we should also get to work embracing new finishes and methods since 1) that's what will be available to us going forward and 2) many of these alternative finishes have gotten pretty darn good if you evaluate them objectively. I rarely use an oil based varnish with my work. From close to the beginning of my woodworking avocation about 12 years ago, I moved quickly to water borne finishes, initially because they were safer to use in the environment I had available and later on because I really enjoy working with them. I still use BLO and/or shellac to add life and color to many species, but the actual film finish I spray is water borne. (Typically EM6000 from Target Coatings, but I also like their EM2000 water borne alkyd varnish product on some projects) I don't miss the long dry times and sticky mess that most oil based products have, either.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  11. #26
    Jim, does there exist a good waterborne/based finish that can be applied like an oil/varnish (wiped on/off?)

  12. #27
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    Very few mfgrs provide data sheets any more and those that do neatly avoid saying much other than dire warnings
    Product data sheets aren't and never were a "cook book" - listing the ingredients of coatings
    They are were/are, guides to the performance of the coatings & specify which standards they meet or exceed.

    Seldom, if ever, is this information needed for over the counter type products.
    OTOH, if you're bidding on a waste water facility and need to know the spread rate @ how many wet mills of a Coal Tar Epoxy that information is critical.

    If you're really hung up on "what's in the can", simply go to a regular paint store in your area and ask.
    A Pratt and Lambert dealer will have more infomation about their #38 varnish than you'll ever want.

  13. #28
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    >>>> so-called oil-base or alkyd varnishes have just about gone the way of buggy whips.

    Almost true. Pratt & Lambert #38 is an oil based alkyd/linseed oil varnish as is Sherwin Williams varnish. Cabot has taken over the McCloskey line of clear finishes and Cabot makes an alkyd oil based varnish. Waterlox Original is a phenolic resin/tung oil varnish while Behlen's Rockhard is a phenolic resin/linseed oil varnish. Any of these are excellent, clear, tough varnishes. You may have to order them and, of course, you will be limited by however strict your local VOC regulation are.

    >>>> The two remaining categories are spar and poly and poly can be just about poly anything.

    Spar varnish is just a standard varnish the is formulated with more oil to make it more flexible. The downside is that it is also less water resistant and less abrasion resistant. Spar varnishes also contain UV additives to protect the finish from sunlight for a short period of time. "Poly" is any varnish that contains an amount urethane resin. Some "poly" is wholly poly resin, most are mixtures of alkyd resin and urethane. Urethane as an additive is to make the varnish slightly more abrasion and heat resistant. But, the bottom line is that "poly" is just a form of oil based varnish.

    >>>> no more natural coatings, just plastics.

    Not quite sure what you mean. Since the 1920's at least, all oil based varnishes have been made with alkyd and phenolic resins. All these resins are petroleum based chemicals. Resins used over 100 years ago may have been more natural but, in general all non-poly varnishes have been made with petroleum based resins for almost 100 years.

    I believe that oil based, high VOC finishes will be gone in a few years. Waterbornes will be the only finishes available for consumer use.
    Howie.........

  14. #29
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    Howard

    What is your opinion on using alkyd varnish on exteriors doors?

    The lighter color of the alkyd varnsh amber makes a huge advantage if you dont want dark amber like Phenolic varnish.


    Many painters use Sikkens Cetol Door & Window on exterior windows and doors.

    http://www.sikkens.us/en/Products/Ex...oorWindow.aspx

    I guess it wouldn't matter if you use Epifanes marine varnish or this.
    It will need to be maintained every 2-3 years.

  15. #30
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    Jim, I meant just what you said, varnish made from natural products. Actually, most alkyd varnish was processed from vegetable oil, not petroleum, along with natural resins. Now its pure synthetic chemistry. Anyway, moving on . . . . how do you find the gloss for a waterborne? I just tried Cabot last night and its awful. I would gladly cease with VOCs if I could find a product that gives me the same gloss and warmth of varnish, plus water base doesn't look well on quite a few tropical hardwoods which is what I mainly use. Long dry times? Hah, I put the pieces out in the sun and they're dry in an hour. On cloudy days, well . . . .those are bad days. I spray every single day that it is not raining. I use my guns so often, I only clean them every few weeks .

    I've avoided the expensive stuff, can't afford the $30-40 qt. varnishes. If I could, I would use the Interlux high build at $43/qt. Most of my finishes are completed with wet sanding and machine buffing. You will laugh when I tell you that I use Ace store brand varnishes which I find as good as any except for marine. Behlens does not impress me at all, way too dark.

    What about waterborn lacquer, what kind of finish does that produce, does it have that blue tint that causes color shifts in redish colored woods? I've used waterborn on the likes of redwood burl and find the color shift is excessive for my taste. I use water base for the insides of all my products so I'm not unfamiliar with it. In addition to high gloss, I need a high build finish for grain filling as well, and wondered if waterborn lacquer is as poor as nitrocelulose. A dry film of 4 mils would be nice, 3 acceptible, 2 mils hopeless.
    Last edited by Harvey Pascoe; 06-28-2011 at 4:15 PM.

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