Sanding sealer or not? Refinishing oak floor. Also: Fabulon opinions?

[Meffy]

I'm about two-thirds done sanding our 1971-vintage oak floor, or so I hope. Here's the question: Should I use sanding sealer before applying polyurethane or not?

I've got two gallons of Fabulon polyurethane and will probably get two or three more, enough to put down at least three coats on about 600 square feet of flooring. The old polyurethane has (at last!) been completely removed and now I'm using medium-grit (80) belts to remove any scalloping or rough places left by the 40- to 60-grit cut. What looked loathsome and scabby is starting to reveal a bit of glow, and all but a few bits of staining and surface damage are gone.

I run into a difference of opinion from books, online sources, and such on what to do after completing the medium cut.

Should I put down a coat of sanding sealer, let it dry, then sand it with fine paper? Or just proceed to a final cut with 120-grit? I have some 220-grit sanding screens intended for use with big stand-up floor buffers. From each I can cut two discs of suitable size for my small car-type buffer -- slow but it ought to do the job. But do I need this step at all?

What say ye, flooring mavens? Should I take back my gallon of sealer and use the money when I buy more polyurethane?

And while on the subject, I'd appreciate any opinions on Fabulon polyurethane. If it's overpriced junk I'd like to return it for credit before opening the first can. What I asked for was a heavy-duty polyurethane that would be highly resistant to moisture (water, cat accidents, et cetera), a real liquid-proof seal.

[Meffy]

All those views but no advice? Guess I'll go ahead and apply the sealer and hope for the best. Today is mineral spirits wipe-down day, and maybe there'll be time to put down sanding sealer in a room or two. I've just a brief spell of weather warm enough to open windows and doors and turn on exhaust fans, so I'll have to make the most of it. With luck my mate and I can move into the place within the week.

Righty, time to get going. I'll post to tell how things went.

[HayZee518]

for vintage oak I would use a sealer. because it is close grained it would help knock down those grainy high spots. fabulon is a great hard floor finish. I have used it for tabletop shuffleboard finishes and I just didn't paint it on, I flowed it on. At $42 a gallon it is the same stuff my dad used on the oak floors where we lived in buffalo ny.

[Meffy]

Great, glad to hear it! I did the mineral spirits wipe-down of all the floors today and got sealer on one room. It's tough because the weather's barely warm enough to open the house up and turn on fans for a few hours a day. I don't dare run the electric baseboard heaters while the vapors are still hanging around, so it'll be pretty cold when I get there tomorrow morning.

Ah well, the results ought to be worth the effort. We have pet cats, so a liquid-impervious finish was mandatory. And for that and toughness both, oil-based polyurethane seems to be the only real choice. So I'll wear my stuffy VOC respirator and keep on brushin'. Good thing there are yard chores to do while coats dry. Whew, it's a busy time for mid-winter.

Thanks,

Meffy Ellis

[Joseph]

Never use a rotary sander on wood

Not sure about the sanding sealer, but I would guess that the most important part of the equation would be whether or not the two (sanding sealer and polyurethane) are compatible from a base standpoint, i.e., oil, spirit or water.
I would guess that Poly is spirit based. The way to tell would be to check the recommended thinning/cleanup solvent.

The main reason I replied is because I'd never use any type of rotary sander and would recommend always using a belt sander and then only sand with the grain. Going across the grain of wood creates noticeable scratches that are then hard to remove. Also keep in mind that with belt sanders you have to watch the courser grit papers and ALWAYS keep it moving.



Joseph

[Meffy]

Yup, as narrated in Catch All I did the belt sanding thing. And did it, and did it, and did some more. =@.o= And learned the DeWalt DW433 really prefers high-quality belts; "bargain" belts nearly always self-destructed even with the most careful adjustment of the tracking control.

I've used the ROS on intermediate/alternate steps, for getting into places where the belt won't, and for smoothing with the finer grits. Once all the sealer's applied and dried (I did one room yesterday as the sun westered and the scant supply of warmth seeped out of the world) I'll use a linear-action finish sander for one or two final cuts. [edit: Think I'll pick up a few DeWalt or 3M 120-grit belts too, in case the little finish sander is too slow for this big job.] I've even used hand sanding blocks for the really tough bits. I was surprised how much faster manual work removed excess wood putty from the patched bits.

Fabulon polyurethane is oil-based, as is the sealer. I made certain of that before buying. The toxic solvents are unpleasant to deal with but all the sources I've consulted said the oil-based poly is significantly more durable than water-based equivalents. I don't want to have to do this again for a LONG time! =^_^= (Though there are three more rooms still with the old, awfully beat-up finish still on... the master bedroom we'll carpet, the hobby room and workshop will probably have to stay as they are for the time being.)

Thanks for the reply,

Meffy Ellis

[Joseph]

One more thing...

I was sure that you understood what sanding sealer was used for so I never commented. But to make sure I'll say that to use or not to use is personal preference.

Although with its use I would imagine that the finish would be slightly more rugged from the standpoint of less catch edges and greater thickness.

The point of sanding sealer is to remove ALL low spots of grain. Oak is a really good example. No matter how much you sand it there is always those little narrow grooves about as wide as a horse hair, their length depends on how the stock was milled. Anyway, it always takes several coats with fine sanding between each to gain the desired effect of sanding sealer, which is to fill up those grooves (see graphic below).

http://home.fuse.net/SpheresOfBalanc...g%20Sealer.jpg

So if you want to do a lot more work to achieve a perfectly flat surface then use the sanding sealer. If you like a more rugged look where you can see the grain pattern has a sort of 3D effect then omit the sanding sealer.

When I was quite young my father taught me this while helping me with my Cub Scout pinewood derby car and a rockets balsa nose cone. Believe it or not it appeared to be made of plastic with no visible mold seams when he was finished. And that’s not a fish story!

Good Luck!

Joseph

[Meffy]

Right, same idea as the opaque whitish sanding sealer I used on wooden models when young. I want a finish that's very easy to keep clean so the fewer grooves and indentations the better.

The way I'm going about this is to sand the sealer about halfway off, so that the high areas of wood are exposed again but the sealer remains in the low spots -- particularly those long, wide-open oak grain pores. They sure do soak stuff up.

I'm still going to use multiple coats of poly, but hope that using sanding sealer will mean there'll be an unopened gallon left over to take back for a refund (got four gallons to cover about 550-600 square feet). That'd be forty simoleons we could spend on a hot water recirculating pump instead.

[edit] Update: I've tried sanding the room I sealed Sunday afternoon and havce run into a problem, presumably temporary. Whether I use 120-grit 3M regular grade belts or 180-grit wet or dry sheets on a 1/3-sheet hand sanding block, the abrasive clogs immediately. Beads of material build up on the paper, raising it above the surface so most of the abrasive doesn't engage. Makes the belt sander skip a little too, even at its lowest speed. I'm guessing that with weather in the 50s F max, the sealer hasn't completely hardened yet... and that I'll have to heat things up to get it right. Now that the fumes are cleared I can turn the baseboards on and get things toasty in here. Hope that does the trick. I've got to get us moved in pretty soon.

[Joseph]

I think you're right about the hardening bit. The baseboards should do the trick. I guess you had them off because of the fire hazard and the dust factor, good call! If only you lived in the southern hemisphere.

I always read the directions when it comes to cold weather. They usually let you know the minimum temperature for application.

Good Luck!


Joseph

[Meffy]

The temperature at best has been around the minimum temperature for decent drying time. I left several baseboards running at higher temperature than I'd normally set them to as I went 'round to pick up a few supplies and will head back over later this evening to turn them back to the usual 60-degree overnight level.

I hope once it's quite dry that the belt sander will cut smoothly without skipping/scalloping as it did on my first try. I'd rather use it with 120-grit belts than the small, slow finishing sander with 100-, 120-, and/or 180-grit paper. But whichever does the job I'm now supplied to get started on this step. Is there any reason I ought not to use the belt sander on sanding sealer? It's a DeWalt 3x18 variable speed, pretty heavy but works great when fed decent abrasives.

*whew* So many steps, each taking longer than my guesstimates. I'm notoriously bad at estimating time and resources. Live and learn, hm?

[Joseph]

I'd start with the finest paper you have. Remember that you're only removing the high spots of sanding sealer and not wood. I'd test in a hidden location (closet). As far as which sander to use, again I'd test in a hidden area.

It's important to keep belt sanders constantly moving. No pressure is required because of its weight; just continuously glide it over the area. A speedy glide will also lessen heat from friction thus reducing buildup on the paper. I'd watch how many passes you make, it may only require one (one pass by you will equal many, depending upon RPM). Use your hand often to check for the desired smoothness.

If you're not comfortable with the belt sander use whatever sander you're comfortable with, keeping in mind that "with the grain" sanding always yields the best job. A lot of orbital sanders have the capability of going back and forth with the flip of a switch.

To extend its life, you can use a file card to remove any build up on the sandpaper.

I hope you've been using a quality respirator for the job, preferably one of those rubber models that have the replaceable cartridges that specify "dust." Of course during sealer and polyurethane application you should use a cartridge for "organic vapor.”


Have you thought about moving in and doing one room at a time? Not trying to be a wet blanket, but I’ve been in your position before and found it extremely stressful.

Good Luck!



Joseph

[Meffy]

I'm using an organic vapor respirator while putting down volatile liquids (or doing indoor chores while waiting for it to dry), and a dust mask when sanding without the vacuum attachment. When the shop vac is attached there's practically no flying dust so I leave that off and wear hearing protection alone. I wanted the cartridge-type dust respirator but couldn't find one so I got a package of twenty disposable dust masks... after which (of course) I found the better ones. *grumble* The aluminum clips on the disposables maim my poor nose, no matter how I shape them. Won't buy the fancier one until I've used all these up, and that will probably take years of small projects. Such is life.

I know about keeping sanders moving. Even the little finish sander "wants" to stick in one place. The previous refinisher used a drum sander, which would be great if she or he hadn't let it stand in one place when reaching walls. I had to deal with shallow (but deep enough) scooped-out trenches allllll around the place. Much of what I've learned on this job has been through observing the existing defects and avoiding to do the same things.

To remove the blebs of build-up on the paper I've been using a small steel scraping knife's flat end, with the pointed end serving to pick off the tough bits, but a file card would probably do the job faster. I'll see if there's enough money to grab one later today.

Can't do the moving one room at a time, gotta get the floors sealed up good so our cats won't ruin the wood. Once that's done, all the other repairs and refurbishings can be done at leisure. In the meantime we've moved most of our boxed stuff and some furniture.

In an hour or two I'll head back over and see how well baking overnight has hardened the sealer. With luck I'll be able to do the whole sand-down today. After that I'll have to decide whether it needs another coat of sealer or it's ready for the first coat of poly.

[Meffy]

Update on the project

I've been putting down poly, and made a mistake using for the second coat the "pour and slop" method recommended in directions from (IIRC) the Consumer Reports website. Could be my incompetence, could be the wrong conditions, could be it's just an ill-advised technique. But I put the poly on too thickly and it formed some thick places where even after days at moderate temperatures I can easily press a nail [edit: my claw, that is, not a metal fastener] into the surface and leave a mark. I've left the electric baseboard heat in these rooms set near maximum overnight in hopes of driving out the remaining solvent perforce.

I'm having a heck of a time getting a clean coat. Even after vacuuming, wiping with towels, then carefully using microfiber tack rags (and wiping down walls and such too), bits of crud always make their way into each coat. The lambswool "mop head" applicator I used for the pour-and-slop coat left more debris than the white china brush. I rinsed it in mineral spirits before starting but that didn't remove all the crud, apparently.

Sooooo... guess I'll stick with brushing -- once the stuff's dried enough so I can get back to sanding and applying again. Wish the weather were warmer, but them's the breaks.

[Joseph]

The cleanest method of applying any coating is via a sprayer.

Any heat source will circulate dust and dander no matter if it's accompanied with mechanical motion or not, it’s all about heat rising (convection).

To experiment: at night with lights out, turn on a powerful flashlight aimed at the ceiling and remain motionless. You’ll actually see the dust particles rise into the air above the beam as if by magic (molecular motion at play).

Let's face it Meffy, on site, we're not going to get anything that even closely resembles the finish that the manufacturer gets in a controlled paint booth equipped with HEPA filters.


Joseph

[Meffy]

To experiment: at night with lights out, turn on a powerful flashlight aimed at the ceiling and remain motionless. You’ll actually see the dust particles rise into the air above the beam as if by magic (molecular motion at play).

Yuppers, this is related to a technique I've used in my medical/dental/forensics work.

Let's face it Meffy, on site, we're not going to get anything that even closely resembles the finish that the manufacturer gets in a controlled paint booth equipped with HEPA filters.

Therein lies the crux of the biscuit. I'll do my best and hope it comes out at least reasonably smooth. Now it's time to head over and see whether the overnight heat has done its job.