Replies

1. 
   Quickstep | Jul 05, 2004 03:55am | #1

   It does sound like witness lines, as if you've sanded through to the previous coat. For that reason, I'd be reluctant to go with two thin coats. If they're thin and you try to rub them out, you might just go through the top coat again. One of the tricks I like to use is to sand the second to last coat dead flat and smooth  (600-800 grit) then apply a final coat of varnish heavily thinned 50/50 with naphtha. The thin finish flows out rapidly and the naphtha makes it dry before dust has a chance to accumulate. After that I apply a coat of wax with a super fine scotch brite pad and call it a day. 

   You need to brush quickly because the naptha makes the varnish dry fast; also, be aware that naptha is more flammable than regular thinner. You may want to experiment with the ratio depending on the varnish you use. I use McCloskey's heirloom varnish and the 50/50 ratio makes it just right for me. You do need to brush it out thin, because the thinned varnish has a tendency to sag.

2. 
   Alan | Jul 06, 2004 01:36am | #2

   Kelsey,

   You don't say what kind of varnish you're using, whether it's oil ("traditional") or poly or water or what ?

   I've seen similar troubles where either the wood wasn't flat beneath the finish, or the finish wasn't quite flattened before the last coat.  That said, it doesn't make sense to me that the steel wool didn't produce an even scratch pattern.

   I've also seen similar problems with poly varnishes.  I don't know exactly why (I never use the stuff myself) but poly has always been known for its difficulty to rub out; it seems to matter quite a bit that coats go on very evenly.  Not being familiar with poly, I really don't know what to do if this is the problem.

   Your description is a little like there are some areas that are softer than others.  Did you hurried the time between coats?  That can lead to troubles like yours.  Small differences in the thickness of a coat can mean one area has sufficiently cured, while another has not.  Putting another coat on top extends the time the under-layer needs to cure, which exacerbates the problem.

   Without really knowing what went wrong:  if you used a traditional varnish, I would let the piece sit for as long as as I could stand it.  A week would be good, a month would be better, two months would be great, longer would be best.  I would let it sit long enough for the varnish to harden completely.  I would then go back over it with a 400 grit wet and dry paper lubricated with some water with a drop or two of soap in it, and level the surface again.

   After that, depending on what you wind up with, you could put on a couple more coats of varnish.  I would not put on a thin coat.  I would use my top-notch badger-fitch brushes and flow on a good, full-strength coat.  Then I'd rub it out once more--again after letting it sit long enough for the varnish to cure.

   I'm stopping now.  I'm tired and my fingers are numb.  Not much help, I know.  A little more information might be helpful.

   Alan

1. 
   Scooter456 | Jul 06, 2004 05:00am | #3

   Behlen Rockhard Table Top Varnish over White Oak.

   Like I said, first few coats were thinned at least 50-50 and mixed with some Tung Oil and Japan Dryer.  Last few coats were Varnish thinned about 80-20 with a tad of Japan dryer, too.  Applied with a Brush.  All coats were left to cure and were not recoated for at least 24 hours.  Final Rub Out was a week after last top coat.  Its been another week after the Rub Out.  So final coats have had now two weeks to cure.

   Must be witness lines or flashing.  I have never seen flashing, but thats my best guess.

1. 
   OneofmanyBobs | Jul 06, 2004 02:49pm | #4

   I don't like Rockhard.  Tried it a couple times with less than great results.  You need to use their special reducer if you thin it.  I certainly would not add tung oil or anything else to it.  You can't simply mix stuff together as many people on the forum are so fond of doing.  The people who put it in the can are chemists.  I'm not.  I've gotten very low success with fixing bad finishes.  Strip and redo with something else.  Waterlox is good.  Just like it comes from the can.

1. 
   aguita | Jul 06, 2004 03:38pm | #5

   Edited 7/6/2004 8:49 am ET by aguita

2. 
   Bobo | Jul 06, 2004 05:59pm | #7

   I had the exact same problem as you using rockhard on a walnut table top. I thinned mine about50% with mineral spirits and when I flattened and rubbed it out after about 5 coats I had the same shinney spots mixed in with rubbed areas.

   I let it sit for about a month and put a final coat of thinned oil poly on top and that hid all the imperfections. I probably son't use Rockhard again. Not that it is a bad product...I just couldn't get it to work for me.

2. 
   HowardAcheson | Jul 06, 2004 05:36pm | #6

   >>I don't know exactly why (I never use the stuff myself) but poly has always been known for its difficulty to rub out;

   Alan, the reason poly is difficult to rub to a high gloss is that polyurethane is added to varnish to make it more scratch resistant. "Rubbin" is scratching so if the finish is scratch resistant, it will not like to be rubbed.

   You can generally rub poly to a satin finish as long as it is fully cured. Full cure takes 3-4 weeks and sometimes more. The more it is cured, the better it will rub out.

   Standard interior varnishes are able to be rubbed out the a high gloss.Howie.........

3. 
   Alan | Jul 07, 2004 01:25am | #8

   Kelsey,

   I think we're on to something--or maybe some things.

   As I said, I never use poly so others know and I don't.  That poly takes a couple weeks to cure sufficiently, and that it doesn't like to be rubbed out sounds good--but you didn't use poly.

   Off the bat I think you didn't wait nearly long enough to begin rubbing out.  It's also possible that one coat a day is too quick.  Either or both can lead to the kind of troubles you're having.  As I said in my first post, it sounds very much like the bottom layers are still too soft.  I've had that exact same thing happen for exactly that reason.  I've too soon tried to fix drips or sags and gotten the same sort of surface you describe.

   I'm told Behlen's bar top is a good product, but I have no experience with it.  It's possible that Behlens merely want to sell their fancy-dancy thinner* but it may be that the usual thinners and solvents just don't work right.  Also, as someone else pointed out, it might cause troubles if you add things like tung oil or BLO or the like.  But again, I don't know.

   Once again I get to cite my one inviolable finishing rule:  there should be no surprises. I always have lots of scraps and cut-offs (read "mistakes") so I always go through my entire finishing process on scrap before I put all my hard work at peril.  (I save all of these.  On the back I write exactly what I did.  They make a great reference for what things will look like.)

   I'm sorry I wasn't more helpful.  I hope you don't need to strip it all off.

   Alan

   *If you look on the instructions on the cans of various makers varnish, lacquer or the like, you'll get the admonition that under no circumstances should you use shellac as a sealer or base coat.  They, of course, want us to buy their product to use as a sealer or base.  What kind of idiots do they take us for?

4. 
   JBD | Jul 09, 2004 12:03am | #9

   Unless I read too fast, no one here mentioned the obvious.  You said that you applied the final rubbing compound with steel wool.  Well, there's your answer.  No matter how fine the steel wool, it is loads coarser than rubbing compound.  And the reason that it is glossy in some areas and not in others?  Thats because of the hydroplaning principle.  The non-glossy areas that are befuddling you are the areas where the steel wool cut through the thin layer of compound in your hand, and the smoother, glossier areas are where the compound was really clogging the wool pad. 

   I was a professional finisher, and coatings chemist for a few years, and I never found a finish that I could not rub out to a decent gloss.  I was able to wet sand and buff the cheap marine spar varnish ("Helmsman" @ Lowe's) on my mahogony boat after only a day in the sun due to careful technique, so a hard varnish like you speak of should be able to be buffed after a week, like you did. 

   Another possibility of the problem could be the introduction of grit to the rubbing stage or creating "polymer balls" unawares.  If your final wet sand stage is not with super clean, or well irrigated 1500 or 2000 grit paper, or too used, it may soften some of the finishing slurry and coagulate it into little balls of goo that will rub dull areas into the finish.  Fine sanding dust accidently blown into the finish will do this too.

   This can all be alleviated by doing the final compounding with a foam pad on a drill. 

   My 3M "Perfect It¯" brand compound will buff even 1000 grit scratches to a gloss.  I use 1200 almost exclusively, then compound, then final glaze (swirl mark remover - insane gloss).

    

   "The furniture designer is an architect." - Maurice DuFrenes (French Art Deco furniture designer, contemporary of Ruhlmann)

   http://www.pbase.com/dr_dichro   http://www.johnblazydesigns.com

5. 
   Scooter456 | Jul 14, 2004 07:45am | #10

   Thought I would give you folks an update.  I stripped the finish down to almost the stain, flattened it, and tried to apply another coat of Rockhard Finish, letting it cure for over 10 days, and then trying to rub it out. 

   This stuff will not rub out.  I spent 4 hours going from grit to grit, and then 4 grades of pumice and finally rottenstone, rubbing compound and wax.  The stuff is dull as talk radio.  Talk about rub out, the whole stone dust thing was over 2 hours of rubbing and I couldn't get a sheen.

   I am convinced that this particular varnish just is so hard that it won't rub out.

   I gave up today, and slapped some poly on it, cutting down the sheen with some wax. 

   This is the last time I use this product.

   Kelsey

1. 
   OneofmanyBobs | Jul 15, 2004 02:52pm | #11

   Harder finishes are easier to rub out.  Soft ones are the difficult ones.  What did you use for a pad?  It makes a difference.  I use a rubber eraser wrapped with felt or a felt block.  If you rubbed for 2 hours, I'm surprised you didn't go all the way through to the other side, let alone just through the varnish.  On a table top, takes me an hour to level and polish.

   If you just use the finest hand glazing compound it wiill give plenty of gloss, but you'll have polished scratches and lumps.  Once you level with 400 and 600 so there are no shiny spots, then you remove scratches and polish.  I go to 2500 wet/dry.  600 - 800 - 1000 - 1500 - 2500.  Always with a backup block. If the finish is hard and easy to sand, sometimes I go to 800 dry with 3M gold paper.  Otherwise, wet from 400 on up.  Odorless spirits usually as a lubricant.  Doesn't raise the grain if you cut through and doesn't need to be cleaned off afterwards.  Absolutely meticulous cleaning between grits with a new clean cloth and more thinner.   Wait a couple days in case the thinner has softened the finish.  Then rubbing, polishing and glazing compounds.  No wax necessary unless you like wax.  Have never found anything that would not polish like that.  Even re-polished a pair of my glasses (but started at 1500 not 600).  Worked just fine and I'm wearing them now. But, you do need a good solid .005 to .010 film to do this.  Any thinner and you will cut through.  If you cut through or see witness marks, stop and apply another coat or two.

   I don't use pumice except for filling.  Too coarse and too inconsistent unless you float it yourself.  4F pumice is only about as fine as 400 grit paper.  Rottenstone is too fine.  I don't use the non-woven pads except on bare wood.  Seems to me they scratch too much.  Just sandpaper and autobody compounds.  I don't like Rockhard, but it can be polished same as anything else.  You just have shiny witness marks and pits.  Level it to 800, apply one coat of very thin varnish, do polishing and glazing compounds only.