Replies

1. 
   Westchester | Jan 31, 2010 09:13am | #1

   yes - allow thorough drying - sand + recoat with a rubbing varnish -

   SA

2. 
   WillGeorge | Jan 31, 2010 11:26am | #2

   I 'think' SPAR is felixabe?
   I 'think' SPAR is felixabe? Not sure a 'Hard' varnish will work over it. BUT then again just MY thought...

3. 
   forestgirl | Jan 31, 2010 12:25pm | #3

   Although I have little experience with varnish, the first thought that occurred to me is along the lines of what Will said. Spar varnish is formulated to "move". I'd wait for some more opinions -- Steve? Howard?

1. 
   Westchester | Jan 31, 2010 12:48pm | #4

   WG & FG
   Good points regarding
   WG & FG

   Good points regarding flexibility. However I don't want to see our friend start from scratch again. Rubbing varnish may not last as long on top of a spar varnish as if he just used rubbing varnish from the beginning - so maybe it only lasts 10 years instead of 15 years - I don't think it's worth the trouble to start again.

   Also you see companies add oil stain to color and tone Alkyd varnishes - it's not all bad.

   SA

4. 
   user-64052 | Jan 31, 2010 01:05pm | #5

   what do you mean by decent finish? what sheen do you want?

   ron

5. 
   Rich14 | Jan 31, 2010 01:31pm | #6

   Scott,

   Yes you can make the change to a "shorter" oil (harder) varnish.

   You will need to give the new varnish a "tooth" to hold on the old varnish. Which means you need to abrade the old surface. Use 180 grit and level it as well as possible after it has hardened enough to sand reasonably well. This may take weeks and the sandpaper will clog a lot. But sandpaper is cheap enough . . .

   Spar varnish is made to never completely harden. This allows it to be used in marine environemnts where extremes of humidity and temperature exceed those of normal "furniture" use. The spar film is thus able to move with the wood to a degree, avoiding cracking and other breakdown.

   But the spar varnish doesn't move on its own. It doesn't make an unstable base for a harder varnish any more than the wood itself. It can't move unless the wood moves. If the harder varnish were the only varnish on wood that moved it would be subjected to the same stresses that it world over a layer of spar. Actually, the spar, if it did any thing at all, might minimize the stress above it.

   At any rate you'll be removing quite a bit by abrading/leveling it for the final coats. You should be fine.

   Rich

6. 
   HowardAcheson | Jan 31, 2010 03:07pm | #7

   Let me make a couple of points and ask a couple of questions.

   Why did you start out with the "spar" varnish?

   What is the item you are finishing?

   No poly varnish easily rubs out. Poly is added to varnish to make it more resistant to scratching. Rubbing out is abrading with some type of abrasive. If your objective is to end up with a high gloss, poly is not the finish to work with. Even standard interior poly varnish is relatively soft. The softness and the poly combine to resist attempts to work the poly to a higher sheen. You will not be able to rub out any poly to a higher sheen than you get right off the brush.

   That said, you want to use a hard non-poly varnish to rub out to a high gloss. The hardest short oil varnishes are Waterlox Original or Behlen Rockhard. Both will rub out to a high sheen. But, both need to cure for 3 to 4 weeks before you begin the rubbing process.

   Finally, many finishes do not adhere well to poly. To have the best chance, you should let the "spar" varnish fully cure for four weeks and then thoroughly scuff sand it with 220 paper. Then apply 3-4 coats of a non-poly varnish so you have enough film thickness to work.

1. 
   Westchester | Jan 31, 2010 03:16pm | #8

   Howard -

   Should he go to the hardest short oil varnish he can find - or something in the middle - I don't think he is looking for that pro high gloss flawless rubbed finish -

   Maybe one level up toward hardness is enough so compatability is closer ?

   Enjoy your comments always-

   SA

2. 
   smajor | Jan 31, 2010 06:34pm | #9

   "Why spar varnish?" -- I was looking for an oil based finish, since oil seems to bring out the colors better. Being rather inexperienced, I grabbed what I found at Home Depot that seemed appropriate. Apparently I need better sources for my finishing products.

   "What am I finishing?" -- Its a large corner desk. The top is a large slab (66" in length, 1 1/2" thick) veneered with mahogany. I've had the slab for ages, and it came veneered, so it's stable. I stained it with various coats of dye and gel stains.

   Being a newbie, maybe rubbing out the finish isn't what I want. My issue is that after 2 coats of varnish, the finish has 'slight' brush marks and some bumps from dust (nibs?). My actual goal is a finish with no brush marks, runs or dust issues. The varnish is semi-gloss, which actually came out a bit more glossy than I had intended.

   Thanks everyone for the input. I am learning!

1. 
   user-64052 | Jan 31, 2010 09:28pm | #10

   just try sanding it out with 240 then 400 paper to level it out. if you are getting white dust in the paper your fine, just as long as it is not gumming up on you. you can add urethane to the spar 50-50 if you want and apply it you can go 100 % urethane if you want

   there is also an art to applying with a brush, good brush and keep the film wet as you apply it. there is even a knack as how to hold the brush

   if you can clean it(level it up) up with paper why not try to apply it with a rag and wiping it fairly dry. it will take more coats but will give a respectable finish. use a mixture of spar and urethane as the spar will give you some slip to work with. straight urethane will dry to fast for you wiping it and will give you problems

   don't be afraid to put enough material on to keep it wet as you wipe it dry progressively into the wet. straight lines on the wiping. if it does dry you can put more on to keep it wet. don't daly and don't stop half way through for anything. I use paper towels (commercial) for wiping off and I try and avoid the ones with bumps and ribbing in them.

   for that final little wipe of each coat I use cheeese cloth

   ron

2. 
   Rich14 | Feb 01, 2010 06:49am | #11

   SMajor,

   Two points:

   1. The fact that varnish is an "oil-based finish" and "oil seems to bring out the colors better" are not really related. It may seem that they are.

   When an oil such as Boiled Linseed is applied to many woods, it "develops" and darkens the color and grain in a way that makes it more prominent. (Then it undergoes a polymerization process, hardening to form a kind of "finish" that is the only finish for many projects.)

   One of the ingredients in many varnishes is the same kind of oil. But after the varnish mixture is "cooked" the individual components no longer exist. An oil-based varnish darkens wood simply because it adds its own hue, wets the fibers and cuts down on light scatter on the surface. It is not the oil that was part of the initial components of the varnish that is doing that. Other, non-oil based varnishes can have exactly the same effect.

   2. You are making an amateur's mistake in your finishing expectations. I mean nothing derogatory in that statement at all. We learn as we gain experience. Simply brushing varnish onto a surface will result in the least attractive final finish. Very experienced finishers can get very smooth flow-out but dust is always a problem with varnish because it is slow drying.

   I completely level sand each coat and after 4-6 weeks of its hardening, level the final coat to remove any last brush marks, dust nibs, etc then begin a rubbing out process starting with 400 grit wet-or-dry sand paper and go up through rubbing compound and polishing compound.

   Here's a "trick" that works very well and often looks as though you've spent weeks rubbing out the final coat. Let your varnish film (I suggest 3 coats) harden for a few weeks. Then level it with 220 grit lightly to remove dust nibs and whatever brush marks you can see. Then apply a final coat of varnish, diluted 50% with mineral spirits (half varnish/half mineral spirits). The dilute varnish will flow like water and level itself without a single brush mark. It should also dry fairly rapidly, and if your finishing environment is reasonably clean, without dust nibs.

   Rich

3. 
   Westchester | Feb 01, 2010 07:21am | #12

   SMajor -

   As others have mentioned - allow thorough drying. Sanding with the different grits - decide whether the desk needs additional coats. After final coat - dry time again - sand up to 600 - followed by a rubbing with fine steel wool to de-gloss the shine then apply paste wax -

   I think that's what you're trying to get to -

   SA