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help! my varnish has pimples,..
"bilgeworthy" wrote in message ... Hi, new varnisher here. When I brush it on carefully, I can see tiny gas bubbles forming in the wake of the brushstroke. snip.. Just a thought...do you stir the can of varnish slowly and carefully before applying? (not like paint can shaking) |
Varnishing can often be more "art" than "science". I don't consider myself
a "pro" by any means, but have spent enough time around the pros to pick up some of their tricks. Sounds like you're using all the main ingredients to a successful varnish job: * using a good brush, "China Bristle" or better, although foam brushes have worked for me, * never shake the can, stir -and- strain the varnish to a separate container, * Schooner Varnish is the preferred varnish of the pros I know, A couple things you didn't mention though, and I'd add: * surface prep: make sure you thoroughly clean and tack rag the surface before each coat (contaniments can cause what appear like bubbles). * air temp / humidity: calm, cool and dry mornings are often the best time to work, gives the varnish more time to settle before drying. * lots of coats: 8 coats as a minimum, most pros I know go with 12 or more. * brushing technique: sounds like you may be moving the brush too quickly, thus generating bubbles. Also brush in one direction, not back and forth. Try to "flow" the varnish on rather than "brush" it on. Of course, there are days when the varnish just doesn't want to cooperate. The "cheat" I've seen the pro's use is using very heavy coats, and "flowing" the varnish on, then if it still won't level properly, they'll wet sand and polish as a final touch. Some folks love doing brightwork, others (like myself) see it as a necessary evil. Trust me, you aren't the first to be frustrated with a varnish job that just doesn't want to work. Good luck! Paul |
The bubbles that form during curing are usually caused from varnishing
during rising temperature. . As cold wood warms the air in the pores expands. I try to lay the first couple of coats late in the afternoon while the wood is warm. As it cools the air contracts and sucks a bit more varnish into the pores. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "bilgeworthy" wrote in message ... Hi, new varnisher here. When I brush it on carefully, I can see tiny gas bubbles forming in the wake of the brushstroke. Most of them pop but some do not and others seem to form during the drying process. The more I try and brush it out the worse it gets. The unhappy result is a beautiful piece of wood with assorted pimples strewn about the finish. I have tried expensive brushes and foam brushes with the same result. I have tried straight varnish, thinner, cheap and dear and 216 (xylene) as brushing agents. I follow the routine from the Brightwork Companion as well as I can. Not shaking or redipping from the can. I'm working indoors with everything at room temp. I have used brand new Schooner Varnish, some old junk in a can and a custom artists mixture of Danar (Damar?) and magic emollients etc. They all act the same. It's less noticeable on 25 year old teak than on newly made woodwork but it's the same result even after 8 coats. I sand out the flaws between coats. I am definitely open to suggestion at this point. Gosh, the old teak just takes your breath away. If I can just take care of this complexion problem. Thank you. |
Glen probably has the answer to your problem.
Porosity in the wood, even with several prior coats of varnish, will sometimes make bubbles as the temperature changes. The use of a 'spit coat' as the *first coat* usually solves the problem. A spit coat is usually mixed as 40%-50% varnish and 60%-50% thinner appied heavy and 'worked-into the grain' with a brush. The extra solvent will greatly 'thin' the mix so that it will penetrate into the intersticies of the wood cells. An alternative is to use a 'sealer' - usually a clear penetrating acrylic that you apply, let cure, then lightly flat sand. Sealers are not really a good idea as they are not UV stable and enhance 'lifting' when the sealer eventually degrades in UV ---- better to use a very thinned-out 'spit-coat(s)'. When I was a 'varnish-addict' I'd wait for the hottest time of the day to apply the spit-coat : let wood get warm, then put up a shade so that the wood begins to cool and apply the spit-coat on the 'cooling' wood. If the spit-coat is warmed a bit, the better the 'penetration'. Also, watch the barometer as a falling barometer will aid in 'off-gassing' during varnish application. I used to prefer(ed) to lay down the first few (4-5) coats with tung oil based varnish for 'penetration' , let fully cure; then a few coats of urethane based varnish for UV protection, let cure a month or two then apply a 2-part clear (Interthane, etc) on top of that for durability ..... and 3-4 years later remove it all when the first coat lost 'adhesion'. I gave up using brushes and found that using a small airbrush is vastly superior ..... and then I discovered the modern 2-part acrylic/urethane co-polymers with heavy UV protection that last 5-6 years; and, havent opend a can of 'exterior' varnish since. |
Subject: help! my varnish has pimples,..
From: bilgeworthy Hi, new varnisher here. When I brush it on carefully, I can see tiny gas bubbles forming in the wake of the brushstroke. Most of them pop but some do not and others seem to form during the drying process. The more I try and brush it out the worse it gets. The unhappy result is a beautiful piece of wood with assorted pimples strewn about the finish. I have tried expensive brushes and foam brushes with the same result. I have tried straight varnish, thinner, cheap and dear and 216 (xylene) as brushing agents. I follow the routine from the Brightwork Companion as well as I can. Not shaking or redipping from the can. I'm working indoors with everything at room temp. I have used brand new Schooner Varnish, some old junk in a can and a custom artists mixture of Danar (Damar?) and magic emollients etc. They all act the same. It's less noticeable on 25 year old teak than on newly made woodwork but it's the same result even after 8 coats. I sand out the flaws between coats. I am definitely open to suggestion at this point. Gosh, the old teak just takes your breath away. If I can just take care of this complexion problem. After 8 coats the bubbles would not be coming out of the wood. So are your sure that they are not small bits of contamination? I've had people tell me that the bubbles they see while applying varnish don't seem to fully pop and go away. And after looking closely at them I've found them to not be dried bubbles but particles of contamination or dust. Are you filtering the varnish? Tacking off well? Applying it outside? Or in a dust free room/area? If they truly are bubbles perhaps you should add a bit more thinner (if your adding any now) to give the bubbles less viscosity to fight and more time to pop. Capt. Bill |
In article ,
says... I used to prefer(ed) to lay down the first few (4-5) coats with tung oil based varnish for 'penetration' , let fully cure; then a few coats of urethane based varnish for UV protection, let cure a month or two then apply a 2-part clear (Interthane, etc) on top of that for durability ..... and 3-4 years later remove it all when the first coat lost 'adhesion'. Just an observation. There are two based types of Varnish. Water or oil based. The difference is that water based is thinned with water and the oil based with mineral spirits, paint thinner. Even if not stated you can tell the difference by looking at what is called for in the clean up instructions on the can. All oil based varnishes contain tung oil or some other type of curing oil. These days it can be a modified soy oil of some sort. The resins in a varnish, without the curing oil, would form an extremely brittle and easily damged surface. The oil modifies and softens the final results making it less brittle. Penetration into the wood is dependant on the viscosity of the varnish not the type of resin used. I agree completely on sealing the wood with a coat or two of varnish thinned fifty percent. However, once that has been done and the coats cure, there is no further "penetration by a finish no matter how much it is thinned. The wood cells are already sealed. Urethane and polyurethane are simply the types of resins used in the varnish deliniating them from non urethane varnishes Non urethane varnish can use natural resins, rosin, amber, or man made resins that form a weaker chemical link then the urethane resins. Spar or marine varnish, in addition to UV inhibitors not found in other varnishes, is what is termed long oil varnishes. They contain a higher ratio of curing oil to resins so they are more flexible and better able to accomodate, without cracking, the higher level of movement that wood experiences in an outdoor enviroment. The use of a non spar/marine varnish under coats of spar varnish can actually defeat the purpose of using a long oil varnish by failing and cracking long before the a spar varnish would have if it was used without the undercoat of the short oil varnish. NOTE; I am just giving some observations of spar and non spar varnish. I am unfamiliar with the acrylic finish you refer too and am not making any observations in regards to an acrylic finish Vs the spar/marine varnish one finds off the shelf. Take care -- Mike G. Heirloom Woods www.heirloom-woods.net |
In article , labomba182
@aol.com says... after looking closely at them I've found them to not be dried bubbles but particles of contamination or dust. An excellent observation. I've found that in the hour or so it takes varnish to dry out of tack it makes a better dust collector then any HEPA filter and is capable of attracting dust from whole neighborhoods. -- Mike G. Heirloom Woods www.heirloom-woods.net |
On Fri, 28 Jan 2005 14:31:48 GMT, Rich Hampel
wrote: then I discovered the modern 2-part acrylic/urethane co-polymers with heavy UV protection that last 5-6 years; and, havent opend a can of 'exterior' varnish since. ======================== Can you recommend a brand that you like? |
I prefer "Honey Teak" by Signaturefinish.com ... starting to be
fairly common on the east coast. The wescoasters seem to prefer "5 Year Clear" by Smith & Co. ... which has a bit of an epoxy base. The stuff is expensive, takes a bit of a learning curve .... in overall cost and overall labor is much cheaper. Once the base coats are applied a very simply scrub with a scotchbite pad and quick coat of 2-part clear yearly is all that it takes .... I double the clear thickness every two years and simply power buff the clear coat . The stuff is very easy to lay down and since it is a catalyzed coating system, you can usually do the WHOLE job on a cool weekend. Initially when applied they have an amber 'hue' but rapidly fade to a light 'honey' -clear color with UV exposure. Both can be hand-rubbed with rotten stone and water (as one can do with varnish) for an 'ultra-gloss' finish. In article , Wayne.B wrote: On Fri, 28 Jan 2005 14:31:48 GMT, Rich Hampel wrote: then I discovered the modern 2-part acrylic/urethane co-polymers with heavy UV protection that last 5-6 years; and, havent opend a can of 'exterior' varnish since. ======================== Can you recommend a brand that you like? |
On Fri, 28 Jan 2005 23:15:29 GMT, Rich Hampel
wrote: I prefer "Honey Teak" by Signaturefinish.com ... starting to be fairly common on the east coast. The wescoasters seem to prefer "5 Year Clear" by Smith & Co. =============================== Thanks. I've heard of both but not yet tried them on anything. |
Subject: help! my varnish has pimples,..
From: Mike G In article , labomba182 says... after looking closely at them I've found them to not be dried bubbles but particles of contamination or dust. An excellent observation. I've found that in the hour or so it takes varnish to dry out of tack it makes a better dust collector then any HEPA filter and is capable of attracting dust from whole neighborhoods. Ain't that the truth. :-) And here in FL we have "love bugs" during the summer that just LOVE that fresh varnish smell. Capt. Bill |
I notice the use of "rotten stone". What is it.
Great articles. Will try some of the tips. Tony S/V Ambrosia |
In article .com,
says... I notice the use of "rotten stone". What is it. Great articles. Will try some of the tips. Tony S/V Ambrosia Rottenstone is a very fine volcanic powder used in rubbing out a finish. It's usually used as the step after rubbing out with pumice. Ace hardware carries it and I believe you can get at home stores. It and mineral oil, acting as a lubricant, on a felt pad of wadded cotton rag are rubbed on the wood to remove very light scratches and further refine the surface. Auto rubbing compound and polishing compound can be used rather then, in order, pumice and rottenstone. They're not quite as aggressive as pumice and rotten stone so you have to rub a bit harder but it does make a suitable substitute. -- Mike G. Heirloom Woods www.heirloom-woods.net |
Rotten stone is a natural mineral used for polishing.
Its finer in texture than pumice or diatomaceous earth. Rotten stone has been used for fine polishing of brass and varnished surfaces for ages. Its usually available in paint stores (right next to the packages of various grades of pumice) and if its a really good paint/hardware store you might find "tripoli" compound for polishing stainless steel, etc.. To use: Flat sand the surface with increasingly finer and finer grades of wet and dry sandpaper (ending with 2000 grit); then for a satin finish use a very clean felt pad with a little bit of oil and sprinkled with rotten stone and rub lightly along the direction of the grain until the surface becomes warm. The heat of friction will also develop an irridescent glowing 'patina' in the wood cells. For an ultra gloss surface as above but using water instead of oil. Best is to simply use a clean bare hand with a few drops of water and rotten stone. If you ever have seen the ultra gloss finishes found on mega yachts, private jets or museums .... this is how they get such finishes. Obviously the varnish must be completely cured before hand-rubbing/polishing. For varnish application just build up many thin layers of varnish and allow to cure throughly before polishing. The frictional heat from the hand polishing will make the varnish look like glass and the wood cells underneath the varnish will absolutely GLOW. There are other surface finishes that are more brilliant (french polishing using shellac, etc.) but are vulnerable to water. Do a websearch for "rotten stone" polish. This is essentially the same technique used for finalizing lacquer finishes on the most expensive automobiles and pianos, etc. . In article .com, Lyn & Tony wrote: I notice the use of "rotten stone". What is it. Great articles. Will try some of the tips. Tony S/V Ambrosia |
These work ONLY on teak and not teak substitutes.
Ive tried them on Iroko and afromosa only to have HT quickly lift (like varnish does). The most impressive thing is the 'adhesion' of Honey Teak with Teak wood. For Honey Teak apply THREE coats of base rather than the recommended two coats. The base coat contains ferrous oxide which is the UV blocker and thus prevents destruction of the surface wood cells immediately under the coating. When you first coat with this stuff the color will look like thinend 'butter scotch' but will soon fade in sunlight to almost clear. Its the closest thing Ive found to varnish but it LASTS, easily repairable. I have a "teakey" and the original application is now going into its 6th season with only one major repair. You can apply with just a soft artist brush and leave it ; or. if you want a 'museum grade' finish you can add extra clear cloats, flat sand, hand rub with rotten stone or POWER BUFF with a highspeed auto body shop polisher and ultrafine (3M) rubbing compound or rottenstone (and water). Interestingly and as with most finishes it seems the flatter and more glossy the final surface the longer lasting the finish. I only get two years out of the clear top-coat. But like I stated previously all it takes to apply a new clear coat is to scrub with a 3M purple pad and flow on more clear with a very soft artist brush .... recoating is very fast. The best temperature for flow application is about 50 - 60 degrees. I've just begun to apply the yearly clear maintenance coat with an airbrush ... looks great but dont know how long it will last. I dont use making tape but just use a large flat piece of sheet metal and shift it along the edges to take the overspray. In article , Wayne.B wrote: On Fri, 28 Jan 2005 23:15:29 GMT, Rich Hampel wrote: I prefer "Honey Teak" by Signaturefinish.com ... starting to be fairly common on the east coast. The wescoasters seem to prefer "5 Year Clear" by Smith & Co. =============================== Thanks. I've heard of both but not yet tried them on anything. |
Forgot to mention ........
For ultra-quality varnish and other coating work and before the actual coating I sometimes take ultrafine pumice and rub it dry on the surface of the wood **** to fill the pores**** of the wood. The result is a smoother top surface of the wood and the pores fill up with the pumice fragments .... which results in less 'out-gassing' bubbles during the first coats. You do have to be careful if the particular piece of wood has many large pores as the accumulated pumice will 'show' through under the varnish. It works for tight grained wood surfaces where there arent many surface 'tear-outs' and 'pores' that need filling. Works better than an acrylic surface sealer, which sometimes yield a 'milky' hue to the wood surface. Surface filling is a trade-off as you get a flatter surface, less out-gassing from the 'pores', etc.;but, lose a bit of the adhesion of the coating to the wood. If your 'prep' is just flat sanding and you dont fill the pores by either using a sealer such as acrylic or pushing in pumice, etc. , you can always get 'bubbles' in the first few coats. If youre in a hurry to varnish, employ the 'six foot rule'.... if you see a defect in the finish develop, step back 6 feets from the surface and if the defect disappears due to the distance just continue on. In reality noone looks closer than 6 foot to a super finish. Hope this helps. In article , Rich Hampel wrote: Glen probably has the answer to your problem. Porosity in the wood, even with several prior coats of varnish, will sometimes make bubbles as the temperature changes. The use of a 'spit coat' as the *first coat* usually solves the problem. A spit coat is usually mixed as 40%-50% varnish and 60%-50% thinner appied heavy and 'worked-into the grain' with a brush. The extra solvent will greatly 'thin' the mix so that it will penetrate into the intersticies of the wood cells. An alternative is to use a 'sealer' - usually a clear penetrating acrylic that you apply, let cure, then lightly flat sand. Sealers are not really a good idea as they are not UV stable and enhance 'lifting' when the sealer eventually degrades in UV ---- better to use a very thinned-out 'spit-coat(s)'. When I was a 'varnish-addict' I'd wait for the hottest time of the day to apply the spit-coat : let wood get warm, then put up a shade so that the wood begins to cool and apply the spit-coat on the 'cooling' wood. If the spit-coat is warmed a bit, the better the 'penetration'. Also, watch the barometer as a falling barometer will aid in 'off-gassing' during varnish application. I used to prefer(ed) to lay down the first few (4-5) coats with tung oil based varnish for 'penetration' , let fully cure; then a few coats of urethane based varnish for UV protection, let cure a month or two then apply a 2-part clear (Interthane, etc) on top of that for durability ..... and 3-4 years later remove it all when the first coat lost 'adhesion'. I gave up using brushes and found that using a small airbrush is vastly superior ..... and then I discovered the modern 2-part acrylic/urethane co-polymers with heavy UV protection that last 5-6 years; and, havent opend a can of 'exterior' varnish since. |
bilgeworthy wrote:
Hi, new varnisher here. When I brush it on carefully, I can see tiny gas bubbles forming in the wake of the brushstroke. Most of them pop but some do not and others seem to form during the drying process. The more I try and brush it out the worse it gets. The unhappy result is a beautiful piece of wood with assorted pimples strewn about the finish. I have tried expensive brushes and foam brushes with the same result. I have tried straight varnish, thinner, cheap and dear and 216 (xylene) as brushing agents. I follow the routine from the Brightwork Companion as well as I can. Not shaking or redipping from the can. I'm working indoors with everything at room temp. I have used brand new Schooner Varnish, some old junk in a can and a custom artists mixture of Danar (Damar?) and magic emollients etc. They all act the same. It's less noticeable on 25 year old teak than on newly made woodwork but it's the same result even after 8 coats. I sand out the flaws between coats. I am definitely open to suggestion at this point. Gosh, the old teak just takes your breath away. If I can just take care of this complexion problem. Thank you. I'm sure you've seen by now that any question about varnish on this group will bring out enough responses from the "varnish is evil" crowd to make you want to hang up your brush. ;-) Of course if you've read Rebecca Wittman, you know to pour from the can through a filter into a container and then thin and brush from that. Keep everything clean. Tack rag and wipe with mineral spirits. Yadda, yadda. If you've done all that you may still be experiencing any one of several problems. First, as has been mentioned, be sure to start with one or two very thin coats to seal the wood. Second, make sure your varnish is properly thinned. This depends a lot on temperature and humidity. Knowing what's best comes with practice. I usually try to get a consistency between whole milk and half & half. See how it drools off your stir stick. Err on the side of too thin. Lastly (and I think this may be where your problem is), there's a technique to brushing. Don't overload or underload your brush. Brush with the grain of the wood and try to brush away from your "wet edge". Start brushing for coverage and then go back several times, each time with less pressure, finishing with strokes so light that you're barely touching the surface. Once an area is done, don't touch it again until it's dry. You can get good results with foam brushes, but I think bristle brushes produce fewer bubbles. After saying all that, you should know that it will never be perfect and there's no such thing as a final coat. If all else fails, you can always invoke the "4 foot rule". Think of varnish as a "zen" exercise and don't let anyone ruin it for you. Cindy -- The email address above is a spam trap. Don't expect a response. Reach me using firstname at lastname dot net |
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