Finishing Question...

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Hi All,
Having a problem with Spar Varnish and dust motes or very small bubbles. After multiple coats of varnish, I sanded smooth, and applied a coat of just opened Marine Spar Varnish with a new brush. I stirred the varnish in the original can, didn't shake! The wood was wiped down with new cheese cloth dampened with mineral spirits to remove any sanding dust.
This morning the finish was dry and there were minute small dust mites, and very small bubbles. I noticed these bubbles or specks when I applied the finish yesterday. There were there with just barely brushing out the finish, and also when I made more very light passes with the brush to try and smooth the finish.
I'm at a loss as to how to fix this, so any help will be greatly appreciated!
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On 4/5/2010 1:02 PM, rich wrote:

A _possibility_...
What is the temperature doing?
I've had that same thing happen when working on cold stuff that warms up while drying
But not when the material is warm, and cooling while drying.
--

Richard Lamb
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Temp has been steady between 60 and 70F, somewhat lower humidity. BTW, these wood trim pieces go back on my boat when done, so they will see sunlight and fresh water. That's why the spar varnish, for durability, and that deep gloss finish.
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On 4/5/2010 1:13 PM, rich wrote:

WOOD temperature, Rich.
Is the material warming (bad) or cooling (better)?
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Richard Lamb
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I guess it would be cooling. The shop is 68f when I'm working, then turned down to approx 60f overnight.
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"rich" wrote:
I guess it would be cooling. The shop is 68f when I'm working, then turned down to approx 60f overnight. ----------------------------------------------- As cavelamb has suggested, wood temperature is probably the culprit.
Keep the heater running for 24 hours prior to application of finish and at least 8 hours afterwards.
If that is a problem, wait for warmer weather.
Lew
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rich wrote:

If you have a boat you really should research what "spar" varnish is and what to put it on. Answers, soft and spars. It is no more durable or glossy than non-spar varnish.
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dadiOH
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On 4/6/2010 6:20 AM dadiOH spake thus:

>

i disagree. It's *very* durable; that's why it's used. More resistant to UV, too. Yes, it's softer, but that's a good thing, too; less likely to crack from temperature changes (think elastomeric paints).
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On Tue, 06 Apr 2010 10:32:35 -0700, David Nebenzahl

Spar varnish is soft, and especially useful for spars, which flex. If you have items that will not be flexing, then there are better and more durable choices, even on a boat. You should especially avoid using it anywhere that abrasion might be a problem. You don't want people walking on it.
There is nothing about spar varnish that makes it inherently more UV resistant, unless it has more or better UV resistance added to it. Read the label to determine if it has any UV additives at all. There is nothing in particular about spar varnish itself that makes it more UV resistant.
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David Nebenzahl wrote:

I disagree with your disagreement :)
*ANY* good marine varnish is durable. And any can have UV inhibitors. The reason for spar varnish being soft *is* to make it more flexible because it is meant to be used on spars - only lubbers paint wood spars - and spars bend. That's not to say it can't be used elsewhere if one is willing to sacrifice abrasion resistance for flexibility.
I speak from 20 years experience owning a 42' ketch with main and mizzen masts, main and mizzen booms, gaff and yard together with trunk cabin, dog house, hand rails, skylight, hatch trim, cockpit and transom finished bright; spar varnish on the spars, regular elsewhere. This was in the tropics, nothing ever cracked from temperature changes (max range maybe 50 degrees).
--

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Hmmmmmmm... I'll try a thinned coat and see what happens. Maybe then the 0000 steel wool and paste wax as a final coat. Apply the wax with the steel wool.
I think after that, the trim will go back on the boat. It's good enough to impress my relatives and kids right now.
Thanks to all for the suggestions. As always, lots of good ideas here!
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"rich" wrote:
.

-------------------------------------- Steel wool on a boat?
Ye Gads.
Lew
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On Tue, 6 Apr 2010 17:13:48 -0700, the infamous "Lew Hodgett"

[Rich, your new name is "Rusty". Do you understand why? ;) ]
-- In order that people may be happy in their work, these three things are needed: They must be fit for it. They must not do too much of it. And they must have a sense of success in it. -- John Ruskin, Pre-Raphaelitism, 1850
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On 4/6/2010 7:49 PM, rich wrote:

Bronze wool laddie. Or one of the synthetic abrasive pads. Not steel.
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Well dust is just dust and the finish is actually a liitle bit charged so it will attract dust from the air regardless.
Air bubbles are likely introduced by the brush. Thinning the material can help so bubbles will be able to surface and pop before the finish films over. Can also try soaking brush in spirits first to minimize air in brush. Can try foam brushes. Can try thinner coats. It is just a technique thing.
Can fix current situation with sand paper and elbow grease, then start over.
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On 4/5/2010 11:02 AM rich spake thus:

So far as fixing it goes, dunno what you could do short of stripping off the finish and starting from scratch. (Yuck!)
As others have implied, dust is just a fact of life. The only way to *reduce* (not eliminate) it is meticulous prep and care in your workspace. Tack cloths are your friend. Working in a clean place that's been vacuumed free of dust helps. If you have to work outdoors, all bets are off. You might just have to live with those dust specks. How bad are they, anyhow? Might not look so bad once you get the pieces installed where they go.
Regarding bubbles, it pays to go over the piece after you've applied varnish and try to pop what bubbles you can see. A needle of some kind works well here. Since the varnish takes a good deal of time to set and will still be flowing, any bubbles you pop will end up invisible.
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I'll look at it again tomorrow. Since it's not house furniture, maybe I can tolerate a lesser standard. I also have to learn when good is good enough. Glad the whole boat is not varnished mahogany! We have two of those on Flathead Lake, but I try and stay away, to keep my drool from staining their decks.
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"rich" wrote:
I'll look at it again tomorrow. Since it's not house furniture, maybe I can tolerate a lesser standard. <snip> -------------------------------------- Surely you jest sire.
When furniture grows up, it dreams of being good enough to become boat joinery.
Lew
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Oh yes... the pinnical of my sawdust making career will result in a copy of this http://www.classicboat.com/id-26triplecockpit1929.htm ... someday
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"SonomaProducts.com" wrote:
Oh yes... the pinnical of my sawdust making career will result in a copy of this http://www.classicboat.com/id-26triplecockpit1929.htm ... someday ------------------------------------------ Understand there is quite a collection at Tahoe.
Otherwise, there is a real hotbed for restoration on L Huron near the western inlet to the North Channel.
Starts getting nippy there along about mid Sept.
Lew
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