Pre finishing hard wood floor before laying down

[Bill Burkhardt]

I've been spending hours searching about finishing wood floors but all I seem to come up with is sanding and finishing after the floor has be laid down, maybe I'm not using the right terminology for my search?

I am using a Woodmaster to make the flooring, 4" running vertical through the machine and so far have had good results with my test pieces and will get down to business soon.

I was thinking to avoid making a sanding mess in the house and fumes that maybe I could just finish the boards first before putting them down, like the refinished flooring that one would buy, but I'm thinking maybe there is an obvious reason this doesn't appear to be what people do. I have put down a few pre-finished floors but this is the first time I am putting down an unfinished floor. So what would be the disadvantage if I finish the boards first?

Thanks
Bill...

[Rich Engelhardt]

So what would be the disadvantage if I finish the boards first?

Uneven floor with a whole bunch of rough places where one piece of flooring comes together with another piece of flooring.
Prefinished flooring has eased edges to minimize this effect.

Just use one of the random orbital type floor sanders you can rent that have a dust bag. The U-Sand used to be excellent, but, some ignorant goof ball that failed to comprehend instructions messed it up for the rest of the planet by leaving a full bag attached to the machine overnight. The bag caught fire and he sued & U-Sand removed the bag. Now the machines blow dust all over.
I've heard that the competition to them that still use a bag work very well. The timing was off for me to try it last time I needed a sander.

As far as fumes, two words - Bona-Kemi.
Just find a dealer that carries either the Traffic or the Mega.
It's water cleanup so the odor is low and short lived.

[Peter Quinn]

Pre-finished flooring has to have the top edges eased or chamfered so that any steps in elevation from board to board are hidden. Flooring is milled quite precisely, but not so precise that it is perfect. A step of .010" is easily felt by hand or foot, its highly likely that despite your best efforts you will achieve errors much greater than that, particularly when running 4" flooring on edge to produce the tongues and grooves. If you are milling these eases into your floor, then its a candidate for pre-finishing, if you are milling square edge flooring it is designed to be installed raw, nailed down then sanded flush. Otherwise you have little razor edges sticking up all over your floor...thats not going to work. I suppose you could hand ease them, or do it with a trim router, routing the tongue side gets interesting, hand easing any quantity of flooring is painful regardless of method. And IME those little chamfers in the pre fin flooring are perfect little dirt wells, crap catchers, scum holders....you get the idea. I vastly prefer a flat floor to one with little lines all over to were detritus may collect and conspire. So thats a down side. Some people don't mind them.

I don't mind the eased edges on wide plank flooring, and have been involved in pre-finishing and installing a wide plank floor for just the reasons you mention (dust control, stink). Honestly, with modern flooring sanders its virtually dust free if the right equipment is used, professional water based flooring finishes have reached maturity and can look beautiful if applied by a skilled person....there is a learning curve on WB products, its not a place to hire the inexperienced or a great DIY situation. So both of those problems can be solved by other than prefinishing. That said one issue with prefinishing is space....as in it takes a lot of it to finish a board, put it on saw horses....finish another.......let them dry....finish some more. It can be done but probably takes 4-5X as long as an in place application. If you have the time and space and are committed to solvent based products its an achievable option.

Third issue is warping. When you finish only one side of a board it tends to twist and warp a bit as each face experiences changes in moisture content differently. With a traditional installation you nail it down first, finish later, so the nails resist and twisting, and the bottom face isn't really exposed to air as much. But when you pre-finish floors on saw horses over weeks it can lead to a bit of twist/warp of you don't finish both sides. And if you finish both sides....it takes at least twice as long and twice as much finish. So thats a down side.

Two years ago I pre-finished about 2500sf of 1X8 ship lap siding for the barn style garage I built, did so in the garage, took months. Every day before work, every night after the kids were in bed for months. Finish 15 boards, dry, flip, finish the other side (the siding really need to be back primed). Stack it....repeat. The issue with flooring is the finish quality is higher than siding, so it has to dry longer and more completely before stacking, you have to be much more careful when handling it, the finishing space has to remain fairly dust free, you need good ventilation regardless of finish type for proper curing. Commercial pre-finished flooring by contrast is a UV cure product that goes through a tunnel system.....from finish application to cured ready to pack in under 2 minutes. Very durable, tough to do touch ups, has that plastic look.

[Tom M King]

With modern sanding equipment, there is little sanding mess in the house. Use Bona finish that suits you, and there is no smell to amount to anything.

Forget pre-finishing. No prefinished flooring can match the job done by sanding, and finishing in place.

If you finish it yourself, just getting someone to sand the floors will cost anywhere from 75 cents to a buck and a half a square foot. You can rent a buffer to sand in between coats. Get the yellow Norton Sand Dollar disk to sand in between coats with. Find out what the diameter of the buffer you can rent is, and order a couple of the sand dollar disks online to fit it.

Buy an 18" t-bar applicator to apply the finish with, and get a replacement cover for each coat. Don't bother to try to wash them out for reuse.

[Nathan Callender]

I dont see much advantage to prefinishing hardwood flooring. Thecommercially prefinished stuff can be really excellent and the finish is very very hard, nuch harder than anything you can apply at home safely. Plus the eased edges scream prefinished and arent nearly as desireable for resale imo. So, i wouldnt spend all the time milling my own flooring just to end up with that look. If i were to mill my own it woudl have to be pretty unique, random widths, unique wood species, etc.

[Malcolm Schweizer]

I would not prefinish for reasons already said above. You get a much better look by sanding the floors and finishing. I redid the 178 year old floors in my house and it was not that huge of a mess. The sander has a built-in vac. I recommend only using the belt or drum sander for the initial two passes, stepping the grit down for the second pass, then go to a vibrating sander for the rest of the sanding. I also used the vibrating sander to sand between coats.

I also also used sanding sealer before varnish, and Minwax floor varnish, only because I could not get Varathane locally. I like Varathane because it has served me well on boats for many years, but the Minwax came out great.

DO NOT use water based. Use the smelly stuff. It lasts longer and the water based will sometimes turn white if it gets standing water on it, like a ring from a sweating glass. That said, there is a reason I call the oil based the smelly stuff. Plan on a few days of open windows.

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[Tom M King]

I looked online for a comparison of floor finishes. This was the best I found without reading a lot of the different ones. http://napervillehardwood.com/Choosing_Finish.pdf

It's only slightly behind the times. I used Moisture Cure Urethanes for thirty years before I got brave enough to try one of the newer waterbournes about ten years ago. Floors I did in the seventies with MCU are still in use, and look good. It's a very durable finish. No regular oil-based can come close. It takes skill and speed to apply, and smells to high heaven as it outgasses the massive amounts of things like Xylene and Tolulene. I still use MCU once in a while. For instance, we painted a small airplane hanger with White S-W Rexthane. The owner wanted a flawless finish, so....don't try this at home....I sprayed it with airless. If I was going to put a coating on a concrete shop floor, that's what I would use as opposed to epoxy.

Having had several decades of experience with MCU floor finishes, I'd never again use it in a house. Oil based coatings would not even make the list that I would consider using. Bona Traffic HD is harder, more durable, easier to apply, and in comparison to MCU, has no smell. Oil based coatings would not even make the list that I would consider using.

I would go as far as saying that to me, it's foolish to use anything else in a house. If you have some wood that you want to keep as natural looking as possible, the Bona Naturale changes the bare color of the wood less than anything else. It almost looks like nothing is on the wood after the first coat.

I owned a big Clarke drum sander, and used it for maybe 25 years, but the first time I saw someone using a German belt sander, I found someone that wanted the drum sander, and sold it. Every since, I pay someone to come do the initial sanding, and do everything beyond that myself. I own a buffer that still works like a new one after 25 or so years, but if I didn't, I'd rent one.

[Rich Engelhardt]

Having had several decades of experience with MCU floor finishes, I'd never again use it in a house. Oil based coatings would not even make the list that I would consider using. Bona Traffic HD is harder, more durable, easier to apply, and in comparison to MCU, has no smell. Oil based coatings would not even make the list that I would consider using.

I have to agree. Cut me and I bleed a solvent of some kind! LOL!
That's how dedicated I was to all things oil and solvent based.
The only single shortcoming to using Bona is - - it's hard to find a place that stocks it.

Well, that and the funky recoat times....

The last floor I did was two years ago this past August.
I had to use oil based Varathane on it. (it was in a rental and the previous tenant had dogs - the oil based sealed out any lingering pet odors)
I was reminded how nasty the solvent based stuff was to work with.
never again...

[Tom M King]

The place I buy Bona, and all sorts of other flooring stuff is a supply chain that will only sell to "flooring contractors". I do all sorts of other stuff, including floors, but I've been on their client list through the past couple of buyouts by other people, so they know me as a flooring contractor. You can order Bona products, and anything else you need for flooring work, online.

[Rich Engelhardt]

I get mine through a place called Pro Source.
They too only cater to the trades.
They don't stock it though - they have to order it.

I see though a place just showed up on the were to buy it. I'll have to check them out.

[Jamie Buxton]

Bona Traffic is a 2-part urethane. The catalyst contains isocyanates. Reading up on them is worrisome. In the short term they can cause allergic reactions. In the long term they can destroy lung function, to cause asthma and emphysema.

[Mark Bolton]

On top of all the issues already mentioned it would be nearly impossible (and even more brutally time consuming) to have your pre-finish not foul up your molding profile which would make assembly a nightmare. The material would run/drip down into the profile while your applying it creating and interference nightmare. Even if you sprayed it would thicken all of your profiles.

The real issue here is other than finish hardness, pre-finishing flooring is a downgrade, not an upgrade. Pre-finishing results in a looser floor, which will have inevitable gaps. You are going to all the painstaking work of milling your own flooring I would be shooting for a floor like a bowling alley. Tight, sanded flat, little to no gaps, screened with a buffer, and a flawless flooded finish. That WAS the norm (and still is for me) and now the homecenters have con'd people into thinking pre-finished is the bee's knee's. I know it has its place and is the predominant system out there now but other than the durability of a factory finish pre-finished hardwood is a downgrade in every other area.

[Tom M King]

In comparison to MCU's, Traffic VOC's "ain't nothing". At least, I don't think it's an illegal finish in some places like MCU's are. If VOC's are a concern, it would be worth looking at Mega. It's a nice looking finish too, and I expect still way more durable than regular oil based, but since Traffic is rated much more durable than Mega, that's the one I go with. We only do one or two floors a year on average, and I wouldn't even worry about the MCU VOC's if I were just doing one floor for myself.

MCU is in fact the finish we have on the floors we have in the house we have lived in that I built in 1980. The Heart Pine floors have never had anything done to them since I built the house, and still look good.

I do know floor finishers that died early deaths. I would never do it for a living full time. Total time I spend in finishing floors in a year might be a couple of hours at most. Putting on the finish goes really fast.

[Tom M King]

Horizon Forest Products keeps it all in stock right on the shelves. I can walk in, grab what I want, and carry it to the counter. Their prices are comparable or better than online. They also carry absolutely anything the professional floor finisher needs, from new machines, to any kind of sandpaper or disk. It used to be called Long Floor Supply, before Horizon bought them out. I bought my buffer from Long Floor Supply something like 25 years ago.

[Phil Thien]

Uneven floor with a whole bunch of rough places where one piece of flooring comes together with another piece of flooring.
Prefinished flooring has eased edges to minimize this effect.

Just use one of the random orbital type floor sanders you can rent that have a dust bag. The U-Sand used to be excellent, but, some ignorant goof ball that failed to comprehend instructions messed it up for the rest of the planet by leaving a full bag attached to the machine overnight. The bag caught fire and he sued & U-Sand removed the bag. Now the machines blow dust all over.
I've heard that the competition to them that still use a bag work very well. The timing was off for me to try it last time I needed a sander.

As far as fumes, two words - Bona-Kemi.
Just find a dealer that carries either the Traffic or the Mega.
It's water cleanup so the odor is low and short lived.

Why did the bag catch fire? How is that contents in the bag substantially different from what we keep in our DC bags?