Calling all able floor technicians. I am trying to get a good finish on a red oak floor I just laid down and things have not working as I envisioned. Here is the problem: I sanded the entire floor to 120 grit with my 4×24 sander. It is very flat and uniform for the most part. However, when I applied oil based pigment stain, the color was blotchy and cloudy in many areas.
I determined that the belt sander was leaving some fuzz that absorbed the stain more heavily giving this bad appearance. The areas that I finished off with 120 grit on the hand block turned out very nice. Subsequent tests with hand sanding to 220 were even better (albiet not as dark as we want).
I am now trying the find the proper tool to handle large areas. I am in the shape necessary to give a coule of final passes by hand to the whole thing, but seeing how this is the first of many rooms to do, I would rather find a faster method.
Has anyone had experience with some of the better power machines for rent, such as the 16″+ rotating machines? Am I likely to end up with cross-grain scratches that would still need to be taken out?
I have heard that there are two types of large rotating machines. One type makes contact only along one side, thus minimizing the cross-grain action. The other makes full circular contact. Do the sanding screens have a higher effective grit due to speed or other factors? The highest grit I see available is 120.
What about the large rectangular orbitals? Any good for the final finish prior to staining?
I have pretty much exhausted other avenues of info. Most books are for the beginners or they talk primarily about sanding prior to clear-coat, where stain behavior is not a factor.
Replies
To refinish an entire floor with a belt-sander is a mistake.
As you've noticed, any areas missed or lightly sanded will be much darker than those sanded or sanded with a finer grit. But you're on the right track;rent a drum or large disk sander, using progressively finer paper.Rent an orbital edger for the perimeter.(Looks like a giant router).This professional method should yield the best results.
The problem is not areas missed. I don't agree with the drum idea. I have used them in the past and they cannot flatten a surface as well as my belt machine. The board ends turned out the best. No dips, gouges, or missed areas. This I did with a combination of the belt running cross-grain; followed by the ROS; then finished off by hand.
The problem with the surface is not missed areas but rather an almost invisible fuzz left by the 120 grit belt. It does not show up until staining. If I work an area more heavily with the belt, it comes out better but that would take more elbow grease than I want to exert. It seems that the back-and-forth motion of the hand block (also 120 grit) does a better job of severing this fuzz. It may also be that I changed this paper more frequently, thus keeping it sharper.
What about these large disk machines? I am trying to find out if the cross-grain scratches will be taken out when progressing up to 120 grit? Or will I have to follow this up with some other process?
I've used a drum sander before,and like you say, they can produce dips,but they also can do a solid job. I've not used the large disk machines,but I'd think dips would be eliminated but "swirl" effects might be seen. Probably best to call or ask the tool rental place.Or post this at BT.
If you're still getting fuzz, change paper more frequently.It's probably not cutting or "shearing" off the fibers as it should. Some refinishers damp mop a bare floor to raise the grain, then sand it.
Edited 1/15/2004 12:55:13 PM ET by JACKPLANE
The new type of machine for floor finishing uses (4) 6" discs that operate as random orbital sanders. Slower than a drum but they will get the dips out. Also, going to 180 will give you a better finish. For floors, changing paper often is the key.
http://www.u-sand.com/
They list what rental companies in your company carry their stuff. Also, go over to Breaktime and ask for ditch.
Hello,
I have used the large disks that you attatch on a floor buffer. Most janitorial supply places carry them in varying grits. I have used them on home floors and basketball courts. The disks look like the sand paper used to flatten joints on sheetrock mud. They will work well even if you are inexperienced. You just have to learn how to use a buffer (push down or lift up on the handle to go left or right)
I would advise on renting a cylinder style buffer if you haven't used them. Several years ago I was refinishing the floors in home. The owner of the company bought a power sander that used cylinders. It came WITHOUT instructions and I had never used them before. He said I could figure it out or have one of my crew use it. We almost destroyed the floor. If you start it without it moving, it will eat a LARGE groove in the floor. We didn't realize this until we were staining the floor. We ended up hiring another floor finisher to fix the floor. Moral of the story: use a buffer with sanding pads.
Are there bigger sanders out there?
I have a sub floor that has developed a severe case of the waves and it needs to be leveled.. I rented the standard Clarke drum sander and it seemed to take all day to remove just a little bit of the curl.. big room, 36x22 hard wood, (tamarck) and if I continued it would have been about 6, 8 hour days to get it level..
I would suggest you crawl under your house and see if there is any unwanted moisture under there. My first house had the floors buckle (both subfloor and red oak floor). About two years before it got sub zero (that is considered cold in Texas). One of the pipes carrying hot water under the kitchen developed a pinhole size leak and was spraying the subfloor. The leak was so small we never noticed it. After two years or so, the floors buckled and had to be replaced in every room but one in a two bedroom house. Insurance covered it fortunately. The house ended up better than when we bought it with new floors and cabinets.
I think the floor may be buckling if there is moisture in the crawl space. If the underside has more moisture, it will curl upward. Kinda like putting the curl side of a board down on a wet lawn in the sun in the summer. The dry side absorbs moisture and expands and the board becomes flat.
In our current house, we had poly put on the ground to prevent moisture coming up and insullation put between the joists. It has made a big difference. We used to have mold in the winter in the northwest corner bedroom. Not any more and the floor is warmer. Everybody further north than Central Texas probably has done this already.
I may be wrong, but it doesn't hurt to check. If you remove the moisture, the floor may flatten out on it own by summer. In my first reply, I ment to say do NOT rent a cylinder sander unless you know how to operate it. duh
Chuck.
I'm building a timberframe.. the flooring is actual 2"x8" Moisture content when laid was around 9% and has varied according to the weather.. (in the dead of winter it gets pretty dry in the house)
When originally laid the planks were squeezed tightly together before being glued and nailed.. (nobody on earth has the wrists needed to screw 4 inch deck screws into tamarack, and if they did the heads of the deck screws would shear off! Predrilling would be needed and since I needed to get everything closed for winter I couldn't take the time..
Now I wish I had.. during the heating season the planks shrank (I only checked the moisture content on the surface. Obviously even two years of air drying failed to get them fully dry) so much so that gaps of as much as 3/4 of an inch opened up.. Grumble but i could live with it, after all it's only a subfloor!
however now after the second year the planks have developed some cupping and are starting to pull nails loose. Not to badly but there is a noticable amount that I would like to remove before screwing them down and then putting a layer of plywood over..
Just for information I have the same cupping on boards in the entryway and those are screwed, glued and splined together.. they are all over the basement and it's drier than a popcorn fart there.. seriously I can lay a sheet of newspaper on the floor tonight and cover it up completely and the next day retrieve it and it will still be dry as the desert..
I think wood does strange things just to mess with our heads. I am a long way from knowing 1% of what Jon Arno knows, I am just a novice. Last summer I put some carbide blades on my 3" power plane. I had some 1" rough sawn purpleheart in the overhead loft in my shop. It had been there for at least 2 years. I barely took off any wood, I just wanted to try out the blades. Two days later the board had warped and twisted a lot. It amazed me to see that. Last week I noticed that a piece of T&G purpleheart had twisted on its own. It had been laying on top of some hard maple, but was not stickered as it should be. It warped and twisted so bad it is useless for much of anything except pens & pencils.
This instruction sheet for floor sanding and finishing covers finishing a floor using rental machines.The rectangular orbital pad sander with 120 grit will give a fine enough finish for a varnish floor -- to cut back between coats a half-sheet orbital sander can be used with 220 grit.
IanDG
you have to be careful about how far you're sanding , is the problem from water damage? you might end up sanding down to the tongue in that case you'd better just start from scratch with a new floor
What you say makes sense. I too have tried the rolling cylinder (or drum) machines. IMO that do not have any inherent flatening abilities and must be finnessed most of the way.
I know someone that regularly uses the janitorial style pad sander with great results, but he does clear-coats. It is the stain that will potentially show the cross-grain scratches.
I think I may try this or one of the large orbital machines. I will then stain a small spot as a test. If it shows, I may just slam some high protein drink and grab the hand sander block. I need to burn some calories anyway.
I only used stain one time on a home floor after using the buffer pads. We ended up using 220#. The circular patterns did not appear. I have used a product carried by Sherwin Williams called Gym Coat (I think). The basketball court looked like glass and the coach loved it. It was a poly based product. Before the finish was applied, we wiped the floor down with push brooms with towels wrapped around them and a solvent poured on them. We made sure all the pilot lights were off in the gym so we didn't go BOOM. On another occasion, we applied a catlyzed finish to a stage. It was supposed to last longer than the Gym Coat, but we had to have new respirators in our masks or it would harden in our lungs.
On another unrelated job, the school wanted one of the stage curtains cleaned as it had a big stain on it. 4-5th grages. I had my guys steam clean it. It looked great but it shrunk about 5". It didn't touch the floor any more. I called the tech support for the company and was told to NEVER steam clean stage curtains because they shrink. I told the school I would clean the other curtain for free just to be nice. They didn't care that they didn't touch the floor. The 10 year old curtains looked brand new and the school gave me several referances. If my high school English teacher was alive to read this, she would fail me for such long paragraphs.
If you have not already finished your project, drop me an e-mail and I'll work you through it. I'm a floor guy. I'm willing to bet you have picked up residue with your belt that was hidden b/t the strips. Old accum. of wax. If this is the case and you ran your paper hard (heated it up) you transfered it to the wood surface and 120 grit is not going to take it out. BTW I Never sand higher than 100 grit with belts.
Use the e-mail on the bottom of my website (I don't give it out in forums for spam sake) http://www.terrawooddesign.com
Chris
Glad to help if I can. I have been sanding floors for 31 years. If I got your message right, this is a newly installed unfinished red oak floor. I'm very much surprised you sanded all of the overwood out with 120 grit on a small hand belt sander. We typically cut new oak with 40 or 50 grit on an aggressive drum sander to get all of the overwood out. We stop at 80 grit with drum and then buff the entire floor with either 100 or 120 grit sandscreen (not sandpaper). The final sanding step should always be rotary to even out other sanding marks and open the grain of the wood evenly. The darker the stain the more it will show circular scratches. I would advise you to use 120 grit at this stage. Drive the sandscreen under the buffer with a tan or green nylon pad. Be carefull where you start with a brand new sharp disk as it will cut hard for the first 10 seconds or so. Try to start new sandscreen in a hidden area (closet, stove inset, etc.) or in the very least the darkest corner of your room just in case you leave a few harsh swirls in that area. After the disk has dulled down a little, go back over the area you started it at. This should remove any overly aggresive swirls. I wouldn't sand over 100 sq. ft. per side on the sandscreen. If you are applying an extremely dark stain, you might consider also renting the rectangular sander after the buffer. I would still use 120 grit sandscreen under this machine but it would help eliminate swirls. I personally never use anything finer than 120 grit on floors. Anything finer starts causing other problems. Just for your info-all sandgrits when coupled with different machines are not created equal. 120 grit sandscreen on a buffer is about equal to 80 grit sandpaper on a random orbit sander. Floorman
Thanks for the info. Actually, I did not sand the overwood with 120. I used #40 belts (on the 4x24 hand machine). I was able to flatten the floor very well with this by being systematic and logical in my approach. I used the same concepts for hand-planing a board on the bench.
Now I am starting to get the picture. I was unaware that you used anything but 120 grit on your 4x24 sander. I'm quite sure the fuzz you are seeing is remnants of grain tearout from the coarser grits. I am not implying you did not do a very good job with the 120 grit but let's face it, sanding an entire floor is not like a small table top that is up closer to eye level and in good lighting. As I see it, sanding with a sander that has a hard plate bottom or platen does not sand the low spots but is better at sanding high spots and flattening. The only way to make sure you sanded the entire floor with 120 grit was if you applied trowel filler to the entire floor and let it dry before you sanded with 120. Then you would be able to see any low spots that were missed because it would still have discoloration from the filler. When all the filler is sanded out, then and only then can you be sure you sanded the entire floor without missing any spots. This is why is mentioned that the final sanding step should be a rotary or buffer machine. The 120 grit sandscreen (which is flexible) backed by a soft nylon drive pad will follow the contour of the floor and evenly sand all undulations and therefore leave you with an even amount of open grain on the entire floor. This will ensure an even coat of stain. This final screening will also remove any places where you unknowingly heeled you 4x24 sander and left a slight mark while changing directions. Incidently, they make a special maroon colored pad for the buffer. Although you could use this to drive the sandscreen as well, it is especially made for between the coats of finish abrasion. Applying two pieces of stick on 220 grit sandpaper (5" for random orbit) on the maroon pad will knock down any grain raise between the coats of finish. The maroon pad is 320 grit. Floorman
OK, you are making some sense here. I could agree that the fuzz was leftovers as you mentioned.
One thing I do during all steps is to mark the entire floor with a pencil to ensure even coverage. I am not likely to rent the big machine, but I will put more effort into providing even coverage. (The wife wants me to save money and work off some of my Christmas dinner that is still attached to my waistline).
My flatness level is quite high so I am not concerned that the flat, hard platten will miss anything. I have good evidence that this is the case. For one thing, the variations in color and blotchiness are on a larger scale not realated at all to the size of the sander platten. In other words, I am not missing small spots that the sander cannot drop into. The blotchy areas were of various sizes, some as large as 2 or 3 square feet. It could be as simple a problem as not spending enough time at 120 grit to thoroughly clean up the surface.
As for dig marks, that was a problem in the past. I have spent so much time handling this machine that I am able to keep it properly grounded to the floor during all types of maneuvers.
Thanks for your advise. You have given me some extra insight that will help. Once this floor is done and looking good, I will probably migrate over to the large buffer machines for the remaining floors. I have more to do than my back cares to handle.
Edited 1/22/2004 9:57:10 AM ET by mlbfreestyle
one quick question for you... when you put the floor down, was it ontop of another floor or did you remove everything down to the floor joists point being if there is a subfloor you may have needed to put down some rosin paper first this helps keep dust from seeping up through the new floor boards ... just a thought good luck
This is all new construction. 2x12 I-joists, 3/4 plywood (sanded for flatness prior to laying flooring), 15 lb. felt paper, then new flooring.
I think the problem is your sanding belts are getting dull. So you get light and dark areas. Look at the floor and see if is blotchy where you changed belts. If that's it GO RENT A BUFFER.
Jeff in so cal
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