I use Waterlox on all the interior woodwork in my own house. It is unaffected by the incidental water splashing in a kitchen or bathroom. It outperforms all regular lacquers and many lower-end conversion finishes.

The pros:
1. easy to apply- I brush or spray a seal coat of 2# cut dewaxed shellac as a sanding sealer, followed by 2 coats of waterlox. Waterlox may be wiped, brushed, or sprayed w/an airless. Use a brush on the drips if you spray.
2. Outperforms most interior finishes for water, UV, and scratch resistance
3. Easy to touch up if it is scratched. Varnishes like Waterlox will stick to a previous coat and feather out very well if you need to restore the finish years later.

The cons:
1. slow drying, and has a foul odor that lingers for weeks, but can be reduced by running a fan over the surfaces for several days after the initial dry time.
2. expensive, costs about $25 a quart
3. Once the container gets about half empty, the rest of the product starts to react with the air and will turn to gel. Only buy quarts unless you know you are going to use gallons on one job. Buy some spare quart cans to save the leftover from the gallon. Keep the containers with as little air as possible.

I understand your desire to do the finish yourself so you know it's quality and know how to repair it if it gets scratched. There are some newer water based finishes, really outstanding products. For what you are doing, I would recommend "Sierra" manufactured by rust-oleum. I get it from Kelly-Moore paint store. Sierra is a water based paint available in any color. For clear coating wood, just get the clear tint base with no pigment added. There is gloss and satin available. Cost is about $30 a gallon

Use the shellac 2# cut as a sanding sealer, then 2 coats of Sierra will give you a bullet-proof finish. It will stick to just about anything, many painters I know use it as a clear coat over painted cabinets. It will refinish just fine, can be brushed or sprayed. I recommend spraying. The finish is dry in an hour. It has no odor. I sprayed a bunch of bar stools in the other end of the room while people were open for business, no complaints. The stools were in use the next day.

Thanks for taking time to write all of this valuable information. Especially about the quart cans. I also appreciate learning about Sierra. It sounds like a good product.

Waterlox told me their product has to be applied to bare wood. I love the idea of using shellac as a sanding sealer/basecoat. I've done it on other woodwork in my house. But I've got oak treads I originally finished with Tired and True Original (combo of BLO and beeswax). Bad idea, but I was looking for nontoxic and easy to touchup, hadn't heard of Waterlox 3 yrs ago.

So, can I just apply a thinned coat or 2 of Sealcoat to the treads (prefer to apply a couple thin coats, it's easier, dries faster, less likely to glob), then apply Waterlox over it? I've been using poly over Sealcoat on my pine doors, but I'd rather use Waterlox on the treads so I can touch them up more easily. I can't afford enough Waterlox to do the whole house (and most of the trim/doors are finished with poly or shellac/poly already).

Thanks, sorry for the hijack but still asking about Waterlox over shellac since it's supposed to be a penetrating oil finish. Or it it really more of a wiping varnish?

Waterlox is not a penetrating oil, It is a wiping varnish. The reason they say it must be applied to bare wood is to sell more product. I've used linseed oil or dewaxed shellac as a seal coat before Waterlox, and I've used Waterlox as the seal coat (as per the mfg. directions) If you put Waterlox on bare wood, it soaks up about 4 times more product than the next coats (and takes forever to dry.) At that rate I could not afford to use it on my whole house, either! But if you use it only as topcoats, the product really goes pretty far.

Waterlox will not adhere properly to lacquer, wax, or water-based undercoats. For your refinishing project, I think you are on the right track. Sand the existing finish to promote adhesion, brush on one good coating of the Zinsser seal coat shellac straight out of the can. let it dry a day before sanding it and giving it a coat of Waterlox. One final coat of Waterlox the following day is all you need. Perform a test on one area before you do the whole stairs. Let the stairs dry 2-3 days with fans running to speed cure time. Do not walk on the stairs until they are cured properly.

I've got some scrap oak, should I put some T&T on that (though can't simulate the aging, I'm not sure how much wax is left on the stairs), then shellac and Waterlox that as a test? Or just do the top piece (that meets the hallway carpet) on the stairs?

So no thinning of the Sealcoat?

I was going to do this while the kids were at camp next week (DH and I can sleep on sofabed), but if I can get a coat (or 2) of shellac on one morning and walk on it at night, sand it next morning and Waterlox it, I can do it just before we go on vacation in August and give the Waterlox an entire week to dry, no need for sofabed.

Thanks

Test on the actual stairs. Do not thin the seal coat. Make sure you get seal coat; regular Zinsser shellac (in the yellow can) contains wax. The time in August sounds ideal, right before your vacation. Leave a fan running while you're away. It will help with odors.

Thanks - I was going to do a test coat of Waterlox on the scrap anyway to decide on gloss (my cousin has some he used on his floors, I forget what gloss level, I think Original). I have Sealcoat (though I probably need to buy more to have enough), that's what I've been using as a washcoat on the pine doors. Also used it on the railing and newel posts last year.

Wow! Only problem is, how do I get the 3-yr old BLO/beeswax mix off the treads b4 Waterloxing?

Remove the wax with mineral spirits. I would also clean with TSP, then vinegar/water to neutralize. You don't have to remove cured BLO as long as you sand for adhesion.

Thanks - this is cured, after 3 yrs! Never did the treads this month since I sprained my ankle right b4 vacation and couldn't go upstairs for 3 days, much less refinish them. It'll have to wait for next summer.