Home |
Search |
Today's Posts |
|
#1
|
|||
|
|||
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) |
#2
|
|||
|
|||
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 |
#3
|
|||
|
|||
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. |
#4
|
|||
|
|||
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. |
#6
|
|||
|
|||
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? |
#7
|
|||
|
|||
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? |
#8
|
|||
|
|||
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. |
#9
|
|||
|
|||
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. |
#10
|
|||
|
|||
In article ,
says... 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. In my not inconsiderable experience with wood finishes I have to note that varnish is one pain in the butt finish to apply when compared to many other finishes. Unfortunately, with bright work, the options I have open to me for other applications aren't viable. First, gloss varnish doesn't need to be mixed. Semi and satin does. Never shake the can, stir gently to avoid suspending air bubbles in the finish before you even start applying it. Thin your first coat or two by 50% and apply it with a rag. If you use a brush be sure it is a natural hair brush, badger, and do not tap off the excess into the can. Gently move the brush across the mouth of the can to get excess finish off. Thin the varnish to around 15% for follow up coats. The less viscous coat allows air bubbles to escape faster. Start you brush stroke with the brush tip and held almost vertically to the surface being coated. Draw the brush slowly across the surface lowering the angle of the brush as the varnish flows out. Tip off the coat. That is, once you have the stroke finished very gently and with just the tip of the brush touching the finish at 90 degrees move it across the finish to knock out any bubbles you do get. DO NOT over work the finish. It is almost impossible to not get some air bubbles in the finish. As you have found, overworking the finish just makes matters worse. That is what they make sandpaper for. DO NOT try to sand off drips and sags. Use a sharp chisel or razor to shave them off. If at all possible DO NOT varnish in full sun. This causes the finish to skin over much too fast to allow any air trapped in the grain of the wood or laid down by the brush to escape. DO NOT apply thick coats. Thin coats are best! Thick coats also slow the rising air bubbles to the point where they become trapped in the curing varnish. DO Not bury bubbles and dust bumps under another coat. Sand them out before the next coat. Waiting, of course till the coat is cured at least eight hours. If I am using an oil based varnish steel wool is my preferred medium for doing that job. If you are using water based varnish steel wool is ok for the last coat but you have to use sandpaper for the in between coats. Decant the varnish to another container for application. Do not put your brush into your main supply or dump anything left in the second container back into your main supply. Doing either will contaminate your main supply with anything your brush picks up. Pour slowly to avoid introducing bubbles into the varnish. Thin coats means you have to apply more of them which takes more time but they avoid a lot of the problems inherent in applying varnish. My preferred method of applying varnish is to head down to Lowe's or Home Depot and pick up a large box of Scott's "Rags in a Box" wipe on the above mentioned fifty percent thinned coats then thin the varnish somewhere between fifteen to twenty percent, the figure isn't critical, and wipe on the rest of the coats. While the above method, what with thin coats and drying time between coats, takes more time to get a good build then brushing on a few heavy coats it avoids most of the problems brushing on heavy coats introduces, air bubbles, drips and sags, dust collection, and can, if one is looking for a really good finish, actually reduce the time it takes to get one since you aren't trying to fix those problems. The use of thin coats makes no difference in the durability of the final finish. I may have forgotten a few things there but it's somewhere to start. Hope it helps Mike G. -- Mike G. Heirloom Woods www.heirloom-woods.net |
Reply |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Teak - Varnish, Oil, Or leave it go blond? | Cruising | |||
new can for Z-Spar Captains 1015 varnish? | Boat Building | |||
Hippo Oil varnish | Boat Building | |||
user of varnish remover on teak | Cruising | |||
The mythology of varnish | General |