I realized after I posted that I just added more issues to think about; but you are correct there are tons of info and misinfo out there about floors in general. Nail polish remover is acetone, and what you removed was probably old-fashioned varnish which I think is soluble in acetone. I'm not sure acetone dissolves shellac - alcohol does that. It's not un common to have multiple different types of old finishes, for various reasons, (You might try some denatured alcohol, or vodka. I use grain alcohol which is the nuts, though sometimes hard to obtain because of laws trying to prevent people from misusing it. I actually have to leave NY and buy mine in VT, by preorder from a State source.) The cracks you see in August (and still now) are likely the narrow ones! Wait until late March rolls around after a full winter of heating. I can lose Bic pens in some of mine. That's when they are easiest to clean out, though. I wouldn't try anything other than emergency washing until the cracks are clean as there is no point moistening that junk in there. It's important that at the end of the season that the gaps are clean as they begin to swell back up. Dirt and debris trapped in the cracks as they close can compress the edges of the floor board, causing increasing gaps the next season. Of course old houses weren't built when there were effective vacuum cleaners so there's a lot of debris down there. As to washing: Murphy's has long been a standby, but has also acquired some (perhaps innaccurate) reputation as being hard to fully remove from floors prior to using poly urethane finishes. I will say this: about a decade ago I was visiting Montpelier, Pres. James Madison's plantation, (he was comtemporary pal of Thos. Jefferson) in VA. I happened to be visiting in the off season and got to wander around a bit more than most visitors. I climbed a staircase and encountered the curatorial staff working on an as-yet-unopened-to-the-public room. They were busily at work washing the floor of the room, with you guessed it: Murphy's and water. So if it's good enough for such an important and professionally cared-for house, it's probably good enough for mine. Otherwise I use Organic Linseed Oil Soap - imported from Sweden, doncha know. I got it from the site that sells the Silent Paint Remover. I find it's an excellent cleaner, smells nice and wasn't particularly expensive since I only use a little at a time. In olden days the floors were sometimes washed with lye, leached out of wood ashes, so I imagine a little Murphy's or Method won't hurt. Floors were also strewn with sand which was then swept up. (That's why you'll likely encounter sand in the cracks even if you're far from the beach.) Don't try washing unless you have a huge pile of rags on had to handdry the floor off at once. Yes, hand sanding or scraping is a one-room-at-a-time type project. More so than renting a drum sander. The only catch is how to meld the meeting point of applied finishes at the threshold when the adjacent rooms are not done all at once, if you don't have a raised threshold. One of the beauties of shellac is that it can be patched up or touched up, or joined together seamlessly anywhere, even in the middle of board in the middle of a room. It's not without its detractions however, the primary one being that it is not bulletproof the way modern poly is. OTOH, should trouble ensue you just clean the surface where the problem is of any wax and dirt and get out a brush and touch it up. It redissolves the old shellac, mixing it with the newly applied stuff and dries so the patch is invisible. Can't say that about any poly finish. You can get it completely off with rags and alcohol and start the whole thing anew if you want. The fix-ability and the reverse-ability have much to recommend it. It is also pretty easily DIY-ish, and cheap. You can search for more info using Google and here on thsi site. But be forewarned there is a LOT of anti-shellac prejudice out there by floor pros, and some people who are just repeating what someone else said. There are also some excellent reports by people who took the chance on it and are very happy. It is relatively slower to apply and more hands and kness sort of work. Don't try it unless you are in a warm-ish, but mostly unhumid time of year. You need to ventilate the room. It is not the worst stuff for breathing, but not benign either. Shellac itself (though not the carrier) is an organic product made from exudations of a beetle in India. I'm imagining you might be interested in seeing what can be learned from your floors. Here are two things to look for (get down on your knees with a good flashlight.) Look for little rows of holes running along the floor. The holes will probably close be together but the rows separated by about 21-27 inches apart. This is evidence of an early floor covering called ingrain carpet held down by tacks. Another thing to look for is evidence how the floor was finished originally (and to know if it has ever been sanded by modern methods). Drum and orbital sanders didn't exist, even sand paper as we know it didn't, so very sharp broadknives were used to scrape the floor flat and ready for finishing. If you hold a light at a raking angle in a place where the wouldn't have been much foot traffic, you may be able to see shallow 1/16th to 3/16 ths inch wide grooves on the surface. This are the still-remaining toolmarks of the original floor's finishing, you are looking at the hand-made work of the floor installer. If you can see the undersides of the boads, say y looking up at the first floor from the cellar, you may be able to see the saw pattern, which can tell you if it was made from logs using a hand-powered pit saw, circular saw, etc. This helps nail down the age of the building because of technology of locally available materials is often known pretty accurately. Have you sorted out which floors are the splintery-est? I have some fir and it has narrow, sharp, fierce splinters. The flat-sawn wide-board pine pretty mellow. Quarter-sawn oak strip is rarely that way. It's not uncommon to find many types of wood in a single house. It's worth learning the correct indentifications of both species and board type (flat, quarter, radial, T&G, butted, lapped, etc.) as sometimes choices of floor finishing techniques are limited by type of wood. Oh, I forgot to add: the reason I use old credit cards (and similar plastic things) to clean out cracks is that the edges and rounded corners are less damaging to the board sides within the groove than metal implements. Plus all the credit cards that are expired get another round of use if recycled into my floor tool box. Card companies used to send out plastic versions of fake ones they use to try and get you to apply for them. I was in plastic tool heaven, but, alas now the facsimiles are just cardboard. Another solvent to try is Soygel. It is particularly, though slowly, useful on floors. Leave it covered with plastic wrap for days, if necessary. Let time do the work, rather scraping it yourself. It also cleans up nicely which is something you can't say about most chemical strippers. All these solvents and the rags used to apply and clean off have the potential for spontaneous combustion. Either air them out on a line for days or dispose of them in a metal, closed container filled with water, and kept outside away from the house. HTH(elps) more than just adding to the overload. L. Here is a link that might be useful: source of Excellent Technical on Info on Care of Old Buildings (NPS Preserv. Briefs)

Wood vs. Engineered Wood? No contest in this case. If the home was built in 1905, put real hardwood in. This preserves the integrity of the home's building materials. Plus, as you can see from the age of these floors, higher grades (i.e. thicker) hardwood can be sanded several times; you usually don't get even one chance to sand engineered wood. The hardwood layer at the top of this multilayered product is simply too thin. Level Floors and Subfloors There are ways to level a subfloor, ranging from replacing parts of the subfloor with thicker or thinner sheets of plywood (or planks, see below), to pour-on leveling compounds that harden to make the entire floor level. What you use to level uneven areas depends on what the subflooring is. If it is plywood or concrete, the compound works. But more likely with this home, on floors at or above grade, there will be wood planks laid at a diagonal across the floor joists. So in your home, the layers were probably joists first, then subfloor planks of wood, then hardwood with tongue & groove joints. You cannot effectively use a pour-on leveling compound on a plank subfloor, as there are cracks between the planks. However, you can lay a new hardwood floor directly on a wood plank subfloor as long as those planks are sound and relatively level. Replace individual planks that have been damaged by water or insects, are otherwise compromised, or even missing (it happens!), with either new planks of lumber, or with plywood of the same thickness as the planks. Any lumber you install, for either the subfloor or finished flooring, should be brought in to your home several days prior to installation, so the materials acclimatize to your typical interior temperature and humidity. Unlike for ceramic or porcelain tile, the subfloor does not have to be perfectly level. And unlike vinyl sheeting, planks or tiles, the hardwood won't "telegraph" minor differences in height, and minor surface irregularities, so the subfloor doesn't have to be absolutely perfect; it should be sound, strong, uniform and essentially level. Your flooring contractor can give you specifics on what upgrades your subfloor may need once the original hardwood is removed. Joists If the floor is significantly not level in parts, or if certain areas feel spongy when you walk on them, I recommend you have your flooring contractor, a home inspector, or structural engineer inspect the subflooring and especially the floor joists. You don't want to invest in a new floor, only to have it become damaged because some joists weren't attended to. Transitions Transitions (a.k.a. thresholds or molding) between existing rooms and the new floor ought to be made of the same wood and same finish (stain, polyurethane, etc.) as the new flooring you are putting down. As wood ages, the finish becomes darker, so trying to make the transitions match the finishes of existing floors is very difficult and not recommended (what will match those floors right now won't match later after your transitions age up a bit). Eventually, the transitions wouldn't match either the new or the old floors! Transitions come in four types: reducer (when the two floors being joined are of different heights), seam binder (when the floors are the same height, and the boards from each are very close to one another), T-mold (when the two floors are the same height, but there is a crack between the two rooms' flooring) and stair nose or stair edger (when the flooring needs to curve around the front of a stair's "tread"--the flat part of a stair upon which you tread!). The transitions for your particular project can be ordered when you order the hardwood, so make sure to include measurements for those doorways/entrances. The contractor can tell you if he/she anticipates there will be a height difference or gap between the floorings, which would require those particular transitions. Dry Air Concerns Consult a local lumber supplier or flooring contractor familiar with your local climate conditions to discuss finishes or other tips for keeping your wood floors healthy in the dry winters. Sounds wonderful! Have fun!

You can use cork (either as a glue down tile or as a click together floor) to work nicely with the wood without competing with it. Cork is technically wood so it works well with other wood products but it is often "non-directional" in pattern so you don't have to worry about a clash of wood grain, etc. Cork can be the fast, cheap way to get a nice warm floor without paying thousands of dollars for in-floor radiant heat. Just a thought.

Laying the new floor in the same direction as the old floor is not the normal way to go about this. In the building industry, it is more common to see layers that are staggered or "bricked". In other words if layer #1 is laid in a North-South direction, then layer #2 (the top layer) is laid perpendicular to it in an East-West presentation. If you want to run the new flooring in the same direction as the old, you will want to use some underlayment (plywood) over top of the old floor so that you can maintain the "staggered" or "bricked" layering system. That is one way to maintain the North-South presentation. Please work with hardwood flooring professionals who have some experience renovating these old gems. They will have seen what worked....and what didn't. Their experience will be invaluable on a project like yours.