Re-finishing An Old Hardwood Floor

Q: I am a little confused about some aspects of floor finishing. I have heard the expression 'raise the grain' and I assumed that meant water swelling the wood fibers. I haven't had a problem with that so far but I'm not really sure if the problem would be now or later, or what it would be, and hope you will explain. A couple years ago I did an upstairs bedroom floor in this same house....another ancient and funky old floor. I used a water-based paint remover first (Back To Nature Multi-Strip) and had to use a lot of water to scrub off the residue, I mean a bucket of water and a scrub brush and pile of rags, just like if I was washing a kitchen floor. After that, I sanded and would use a wet sponge mop to remove the sawdust in order to see what my results were and if I needed to sand some more. I always let the wood get really dry before re-sanding. When done with all the sanding and wiping and re-sanding and the floor was bone dry, I used tack cloth to remove every last bit of dust. Then used a walnut stain, then urethane. That was two years ago and I haven't had any problem with that floor yet. What is the story about water swelling the wood fibers? I used a lot of water in doing that floor and I'm sure some of the wood fibers must have swollen at some point. So will that come back to haunt me in the future? So far all is smooth and shiny.

A: Raising the grain with soft woods is very common in furniture making. The problem with water on wood is multifold:

1. It swells the wood, which can lead to buckling and twisting - especially if the wood has been laid very tight board against board.

2. In furniture, the wood is generally open to air on one side -if you look at a dresser, the outside surface is finished with a sealer but the inside surface is not sealed, this allows any moisture to find an easy exit for evaporation.

3. With flooring in newer homes, it is more than likely that the underside of the boards are laid on sheathing such as plywood or worse, particle board, which swells the instant it gets wet and does not shrink back when dry. In your case an older home, the boards are most likely the floors themselves and hence they are not "sealed" on the bottom allowing air to take care of any moisture problems that might develop. As well, when there is no airflow around the floorboards and they are damp, they will begin to rot. Water spilt on a carpet that has wood underneath, will feel dry to the touch after a period of time, but the water has penetrated the floor boards.

4. If you used water and the boards are 100% dry, then you shouldn't have a problem. Most people don't wait for the boards to dry out completely. The surface water may have evaporated, but that does not mean that all the moisture that penetrated the wood has dissipated. If you seal a board that is wet inside, and there is nowhere for the water to escape, the board will begin to rot.

5. Wood can only absorb so much water, if they are wet when you apply a water based stain it does not penetrate the boards to the depth it should.

Link

Finishing Hardwood Flooring

Q: I have a question about finishing wood. I have sanded down the wood in preparation for putting on a shiny topcoat of varathane or polyurethane. When I finish sanding I wipe off the sawdust with a wet cloth. When the floor is wet it looks much darker than it does when it's dry. Does the coloring of the floor when it is wet pretty much give you an indication of what the coloring will be when clear polyurethane or varathane goes on?

A: The floor should be wiped with a tack cloth not a damp cloth. Water swells the wood fibers. It must be 100% dry before you stain, not 99.9% but 100%. The wet darker appearance is Not a good indication of what you will get. A clear high quality urethane will not change the color of the floor.

Link

Can't Afford To Refinish My Hardwood Floors

Q: I too need to have my floors refinished but it isn't in the budget. Could I just clean the floors really well and then put a polyurethane on them to hold me over until "someday" comes when it might be in the budget?

A: Their are two problems with adding a coat of urethane over your hardwood floors. The first is that you will seal in any dirt, grime and other marks. The second is that if there is any wax or varnish on the floor the urethane will not adhere to it.

Link

Gaps In Hardwood Floors

Q: I'm trying to fill the gaps in my wood floor with wood filler. My plan is to stain and then coat with poly but the filler seems to be flaking and chipping (there's some movement in the boards when we walk on the boards nearby). Will this stop when I poly it? Also, how many coats of stain does it take to turn this yellow stuff (wood filler) brown?

A: The floor must be solid, wood fill will not strengthen the boards! It is chipping and splitting because the adjacent boards are moving - there is no flex in wood fill. The stain will not make the yellow fill look like the wood - ever!! Wood and fill take stain completely differently.

Link