Replies

1. 
   HowardAcheson | Dec 13, 2002 11:32pm | #1

   Spar varnish is a very high oil content product to make it flexible and soft. Adding more oil to it will make it even softer therefore reducing its ability to withstand abuse. In addition, good spar varnishes are made with phenolic resin and loads of UV protector additives. This gives it a very yellow color. It's softness also makes it difficult to "rub" to a finish.

   Personally, I would not use it for an indoor project that will get much wear. Interior short oil varnishes and poly varnish are a much more durable finish and their hardness makes them a better candidate for "finishing the finish."

1. 
   RickL750 | Dec 17, 2002 06:19pm | #6

   Thank you all for your input.

   Rickl

2. 
   Alan | Dec 14, 2002 04:53am | #2

   Rick,

   What Howie said!  (But be prepared for Gretchen to disagree.)

   A good furniture grade varnish (NOT poly!!) is just as easy to apply as spar varnish.  If you don't already have one, spend some dollars on a good badger-fitch brush.  It really does make a difference.  As usual, you won't regret buying the best tool.

   Also, as Howie wrote, spar varnish is just too soft to be rubbed out properly.  Not true with good furniture grade varnish.  Buy glossy varnish.  Matte and other finish varnishes have softeners added to get the less than glossy surface.  Because you have to rub out varnish anyway you can get whatever sheen you want by how far you go rubbing it out:  you can stop after 0000 steel wool with wool lube for a matte finish, or go all the way through rottenstone for a high gloss.  Using glossy varnish means you will have the hardest finish with whatever surface texture you want.

   Alan

1. 
   SgianDubh | Dec 14, 2002 05:50am | #3

   Alan, as I understand it, silica is added to oil based varnish primarily to achieve the sheen desired without further work. Apply, let dry, and there's the sheen. Silica breaks up the refractive and reflective properties of the dried film, much like light refracted and reflected by an unbroken mirror (gloss) is somewhat different to light refracted and reflected by the same mirror, but broken-- e.g., satin, matte.

   I don't think silica is generally added  to specifically act as a softener as your post seems to suggest. As to the hardness of dried varnish films with added silica compared to an unsilicated gloss, my understanding is that the difference in the hardness of the film coat is only really measurable in a laboratory--- and of course I may be incorrect here. 

   In my experience, it's not at all necessary to rub out an oil varnish to the desired sheen. I seldom do so. I try to maximise profits by omitting this tedious and time consuming process altogether. If I want gloss, I spray gloss. If I want satin, I spray satin, etc., or apply the coats by whatever other method I've chosen. However, I'd agree that if you want to be in complete control of the sheen level, I'd apply gloss because this can be rubbed out to whatever sheen is prefered.

   My comments refer specifically to oil based alkyd varnishes which I use a lot. I rarely use oil formulated polyurethane varnishes, and I don't use water based varnishes at all. Slainte.Some stuff I've made.

1. 
   Alan | Dec 14, 2002 01:32pm | #4

   Sgian,

   I will bow to your superior knowledge of how varnish is made.  I was simply repeating what I was told by a tech-help person many years ago.  As I now remember, he said they added something (the actual ingredient escapes me.  Wax?  Oil solids?  Something like that.  Or another senior moment?  Sigh.) that prevents the varnish from forming a glassy smooth surface, but also has the unfortunate consequence of making the finish a bit softer (I did not mean to imply that they wanted to make the finish softer).  Though this was fifteen or more years ago; I have no idea how they now make the stuff.  I'm sure you're correct, that they use something that doesn't compromise the product's toughness and durability.

   You're also right that you can get away with not rubbing out varnish.  And if I was finishing or refinishing for a living I would certainly look for ways to avoid what you accurately described as a long process (though I can usually rub out a piece in less than a day--so long as it's not too big or has too many nooks and corners).  But without rubbing out I'd be stuck with the little nits and nobs that seem to invariably land on my varnish while it's drying--no matter how carefully I've cleaned and dusted and sprinkled the paint room.  Drying varnish seems to attract dust particles like a mobile home park attracts tornados.  I've never yet had a horizontal surface dry without those annoying tiny bumps.  Not having to rely on finishing for a living gives me the luxury of being able to rub it out without the nagging feeling that I'm wasting time.

   There's a second reason I rub out varnish: the gloss that comes out of the can, at least to my eye and touch, has a more plastic look and feel to it than a finish that's been rubbed out to approximately the same gloss.  Sounds weird, I know.  It seems that a gloss finish should be a gloss finish.  But then I think the same thing of poly (yeech!) it looks like plastic, and feels like plastic.  (One of the reasons I never touch the stuff.  Like you, I use only oil based alkyd varnish--glossy.)

   Alan

   Edited 12/14/2002 5:51:45 AM ET by Alan

1. 
   SgianDubh | Dec 14, 2002 04:41pm | #5

   Alan, I'm not an expert on polish formulations, and no doubt your tech-help person was correct in stating that varnishes other than gloss form a somewhat weaker film than the straight gloss-- but as I mentioned earlier, the weakness, as I understand it, is really only detectable in a laboratory, and has no real significance to us as end users.

   As far as I know, silica is the (universal?) agent added to impart the sheen in all the polishes I use-- including varnishes, pre-cat lacqers, etc.. It's the off-white gunk at the bottom of the can. You can apply a matte varnish that's been sitting on a shelf undisturbed for a long time where the silica has fully settled into a hard cake at the bottom, and it will dry glossy if you make a special effort to not disturb that bottom gunk as you stir. Keep your stick off the bottom, and stir gently. But why bother, when a can of gloss freshly purchased does the same job, ha, ha.

   However, somewhere in the back of my mind there is a memory of a finisher mentioning to me that one varnish maker has a distinctly different chemical formulation for its gloss varnish to its lower sheened varnishes, and this can cause problems. I can't recall the brand, and as it's one I don't use I rather neglected to store the information securely!

   There are a couple of tricks I do get up to, which might be useful for others. If I'm applying multiple coats of varnish, I apply gloss throughout the process for its clarity, and reserve the sheen I want to use for the final coat-- or maybe two coats if I'm rag wiping the stuff on. I don't often apply more than three coats of varnish if I'm  spraying or brushing it on, but I've found that multiple coats of dulled varnishes tend to occlude the grain and look a bit 'milky'. It's hard to describe, but I suspect it's all those layers of silica that leave the look a bit dull, so to speak.

   A good looking high gloss is hard to achieve straight out the gun or off the brush, and yes it can look a bit plasticky too. One way around this, and still get a very attractive 'near' full gloss is to add 5% or 10% of a well stirred satin into a full gloss varnish. It just knocks off that shiny artificial layered look, but is still quite bright and shiny. Naturally, it's safest to stick to one manufacturers products, e.g., knock off the sheen of Pratt & Lambert's (P&L's) 38 alkyd gloss varnish by adding a bit of P&L's 38 satin varnish.

   I agree, that dust and varnish seem to be mutually attracted to each other, and it can be a problem, and this is why some people will will wipe on a final coat or two over sprayed or brushed on lower layers. Another trick is to thin out a final coat of sprayed varnish with white (US mineral) spirits for faster drying-- see attachment, or for even swifter drying use naphtha. Slainte.Some stuff I've made.