Still having grain filler problems

[Randall Frey]

Hey guys, a follow up to my previous posts. I worked a bit more with the grain filler on the (table leafs only). After a few coats and alot of rubbing I thought I was there. Holding a light at an angle to the piece I could still see the grain was not 100 percent filled but thought maybe this is as good as it gets and the finish coat will do the rest.
I gave it 2 coats of wipe on poly sanding between coats and the grain still shows. I am looking for a mirror finish, I don't want to move to the table top until I get this right. So, now that I have poly on the leaves, am I scr...d? can I use more filler over the poly? Had I not applied the poly how many coats of filler should it take to get all of the grain filled?
One other thing, after applying the filler, and working to get the residue off I could see tiny scratch marks from the burlap so I switched to a terry cloth which offered enough abrasive to get the haze off but in the finished product I could see overlap lines from each application. The poly top coat has almost made them go away but I can still see them. I hope you all can help me!
Randy

[Dennis Peacock]

Randy,

If you want a true mirror finish, then poly isn't the finish of choice as when rubbing out the finish as you could get "witness lines" when you sand or rub through one of the film layers. The best finishes for rubbing out are lacquer and shellac (chemical curing finishes). The longer the dry time the better and easier the rub out will be.

To get over where you are now? I would sand the clearcoat off or down to where the entire top is dead flat and all grain filled. If not, apply more finish, sand it down again and recheck. I don't believe that filler will stick to poly, I could be wrong, but I learned the hard way....put on finish, sand it off, put on more finish, sand it off, put on more finish......well, you get the idea. :)

[Carl Eyman]

I had very good success using a water based filler and a water based varnish over mahogany. As you know it is a very open grained wood. My other successes have been over walnut. There I just put enough shellac on to fill the pores (12 - 15 coats) and finished with Behlen's rockhard varnish. I'm not sure what you can do to salvage the work in process. When you attack the rest of the table you might make a practice run or two to see if a thinned filler would get down into the pores better. Perhaps you need to work the filler into the pores better with a plastic spatula better. I used the plastic tools you can buy in the auto parts store for body putty. Once you get the practice piece the way you want it you have to decide on the finish coat. I would doubt you'd find poly as good as shellac, lacquer, Behlen' Rockhard or Fuhr's #355. By the way, FWW in a recent article tested a number of water based products. Fuhr's 355 rated very high on the list - better than their "best buy", not as good as their winner, but much cheaper. It is not good for brushing, though. It sprays like a dream and being water based does not require a spray booth.

I'm afraid the leaves may require a bunch of sanding. Keep a stiff upper lip. (varnish in your mustache helps)

[Steve Schoene]

You can fill with a finish, though poly doesn't sand very well. With a wipe on varnish you can expect 6-8 coats, or even more, not two or three, It takes about three coats of wipe-on to equal one brushed on finish. And, brushed on varnish gives you much more leeway before cutting through the final coat and getting witness lines.

Another important point is that you must wait for everything to be fully cured before sanding the final coat smooth and rubbing it out. With oil based finishes this takes roughly a month. If you sand it off too soon, the finish will continue to shrink, revealing the grain again.

[Doug Shepard]

The few times I've used filler (oil-based) was on red oak and I just put it on the bare wood then resanded afterwards. I saw the earlier thread about putting it on over sealer and got curious. At little reading says I probably did it wrong? But the results came out great and I didn't have issues with sanding through finish layers. What's the verdict on bare wood use before any finish?

[Steve Jenkins]

The few times I've used filler (oil-based) was on red oak and I just put it on the bare wood then resanded afterwards. I saw the earlier thread about putting it on over sealer and got curious. At little reading says I probably did it wrong? But the results came out great and I didn't have issues with sanding through finish layers. What's the verdict on bare wood use before any finish?

There is nothing wrong with putting filler on bare wood. It can be used as a combo stain/filler when you do that. If you don't want it to stain the wood then you use a wash coat of sealer first. This is a sealer or finish that is thinned down about 3 thinner to 1 finish. It just prevents the stain in the filler from penetrating the wood so the only place it ends up is in the pores.
the reason for thining the seal coat is to keep the edges of the pores sharp. If you put a heavy coat of sealer on before filling, the pores are somewhat smoothed out and the filler won't stick as well.
It isn't unusual to need two or three applications of filler. Be sure to let it dry well between applications.
I gave up on burlap because of the scratching problem and now use cheesecloth to remove it, then a paper towel or soft rag to wipe with the grain to remove any haze. When removing the filler with the cheesecloth or burlap turn the material frequently. When you get a build up of filler in the material it will start to pull it out of the grain instead of packing it in.

[Randall Frey]

Thank you all for your help. I have the book "Great Wood Finishes" by Jeff Jewitt and in reading up on grain fillers, he states that an oil base filler can be applied over any sealer, this, I believe, answers my question if filler can be applied over poly. Not dicounting the theory of too much sealer rounding the edges of the pours. In addition, he says that when you apply the filler, to scrape the excess off (in the direction of the grain). The can says scrape across the grain which I did. I wonder if this is why it doesn't seem to fill so good even after a few coats? Jeff also suggests if after the burlap treatment you still see some filler to lightly moisten a cloth with naptha or mineral spirits to get the rest off. I really think the burlap is too abraisive as it did leave small scratches. Maybe if it was washed first it might be softer, I am bagging the burlap for cheesecloth for now. Anyway, I would like to scuff sand the poly on the leaves and try to apply another coat of filler scraping with the grain. What do you all think about this? Thanks once again. Randy

[Steve Schoene]

Scraping with the grain is mostly for gross amounts of excess. If you scrape very much in that direction you will be pulling the filler out of the pores. So, the initial wiping or scraping of the filler, when it first hazes up, should be cross grain. Then it should be let to dry. Only after it is dry or mostly dry should any with grain sanding or scraping be done. By the way, I doubt that the burlap was leaving scratches except in the remaining filler. If you could see those scratches you are leaving too much filler on the surface.

The particular wood wasn't mentioned. Oak (or ash) are difficult to fill, and almost certainly require more than one coat of filler. Mahogany or walnut ought to be able to be filled with one coat of filler.

If y ou are seeking a true mirror finish, you should use lacquer (or shellac) as your top coat. Varnish is very difficult to achieve a high gloss finish. And, poly is more than just very difficult, it is extremely, extremely difficult to achieve a truely high gloss finish. Wiping varnishes are also very difficult to rub to a gloss finish. The coats are not thick enough to do more than a very light rubbing out. If you want a high gloss finish with varnish you should go to a traditional resin varnish such as Behlen Rock Hard, and thin it only to brushing consistency0--about 10% thinner.

[Tim Sproul]

In addition, he says that when you apply the filler, to scrape the excess off (in the direction of the grain). The can says scrape across the grain which I did. I wonder if this is why it doesn't seem to fill so good even after a few coats?

When you do it the way Jeff details, you need to consider 2 things, IME. The scraper is a flexible rubber squeegee, not a hard piece of wood or plastic or metal. Second, I've had best results tilting the squeegee pretty far forward....tilting it so that you're pulling the squeegee edge helps to keep the filler in place. Experiment with how much pressure you apply and the angle you hold the squeegee/scraper. You can also try going more diagonal to the grain.

You also shouldn't expect that the level surfaces will have no coloring due to the filler (I'm assuming the filler is colored). Filler is essentially thick stain. Sealing the wood gives you more contrast between the pores and the level surfaces compared to applying filler to bare wood and can help make removal of excess filler easier. The effects of sealer depend on how much sealer you applied....wiping on a thin coat of 1/2 pound shellac won't do as much as brushing on a 2 pound coat of shellac.

If you are striving for a piano finish, I'd suggest you use a clear coat that burns in or at least a clear coat that you can apply successfully in thicker layers than what is normally achieved by wiping on. For me, I've done some smaller pieces and I've had to spray on 2-3 coats....level sand, spray another 2-3 coats and level sand. At this point, the entire surfaces gets to be level....and appears like a piano finish. Add a few more coats before polishing so that polishing doesn't cut through to these 'base' layers of finish.

[Randall Frey]

Ok, so if I change horses now which I am not oppose to and use a sealer that can be rubbed out I have a few questions. I chose wipe on poly because I have read that it is tough and also ease of application, no spraying ( I have a new spray rig but haven't mastered it nor have a place to spray) Is there another sealer that I can wipe or brush on that will resist all normal spills and bumps a Dining table might recieve. And now with my given situation which is all Sapele, (Mahogany) top pieces have 2 coats of stain and 2 coats 1lb cut wax free shellac, the leaves have been taken further and had grain filler and 2 coats of poly applied. What would be the best way to proceed that would accomodate all pieces to a finished mirror tough finish? I prepped another test piece with stain to try another route if needed. This rock hard finish sounds interesting hmmm. I am not usually so needy but I have spent a long time building this table and really want it to turn out. So, thanks in advance for all of your input.
Randy