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Preparing and Staining an oak floor


rolson's Avatar
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12-06-06, 09:40 AM   #1  
Preparing and Staining an oak floor

I have a house that was built in the early '50s. I recently pulled up carpet that has an oak floor beneath. Only the outer edge had ever been stained and varnished whereas the rest of the floor was unfinished. Underneath the carpet was like a sandpit. I vacuumed and removed the stain & varnish with Zip Strip of some sort, I sanded the entire floor with a random orbit floor sander (40/80/120 grit). After sanding, the unfinished area of the floor was slightly darker in color than that of the outer edge where there used to be varnish, but nothing drastic. After trying to stain a portion of the floor, only the outer edge took the stain nicely whereas, the middle took the stain much darker and somewhat blotchy. My questions are what caused the darkness and how do I fix it? Like I said, the color of the stain along the outer edge (~1ft) matched the can color nearly perfect. Any suggestions would be greatly appreciated.

Thanks,
Rory

 
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Just Bill's Avatar
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12-06-06, 03:22 PM   #2  
This is a tough one. Part of the floor has had a finsh and been exposed to the sun(UV), where part has never seen light of any kind, nor a finish. The previously unfinished wood has dried considerably and may be more or possibly less receptive to the stain. If you sanded the exposed part of the floor to below where any finish penetrated(not likely), all should stain/finish the same, but that obviously is not the case. At this point I would suggest adding a coat of stain to the previously finished area, and pray that they match, otherwise start sanding again.

 
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12-06-06, 04:27 PM   #3  
The area beneath the rug where there was never any finish to seal and protect the floor likely darkened from ground in soil and overwetting when carpet cleaning. Because pores in the wood were open and never had any finish, wax, oil, etc., they sucked up more stain than the previously finished areas. The blotches may well be due to where something was spilled and absorbed into wood. Oak generally takes stain very well and is usually not prone to blotches. Note: Some strippers contain wax and can interfere with absorption and adhesion.

What type of stain did you use? Oil or water-based? Application method? Usually finishing with 80 grit leaves pores open and ready for stain.

I also wonder if you sanded the floor enough? Medium grit usually cleans the floor very well. If floor did not come clean with medium grit, perhaps more sanding would have taken you down to clean, raw wood. If not, coarser grit can be used before changing to medium and working your way down to finer grits. The same grits and number of passes should have been used on both the finished and unfinished areas. Too, you are not supposed to skip more than one intermediate grit number. You started with 40, skip 50, use 60, skip 70, use 80, etc. You say you went 40/80/120.

To remove existing stain will require resanding down to bare wood. If you did not properly sand the entire floor, you may want to consider resanding the entire floor.

Go to www.nofma.org and click publications and download for free the National Oak Flooring Manufacturers Association's technical manual for Finishing Wood Floors.

 
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12-08-06, 04:26 AM   #4  
Thanks for the replies.

To answer some questions, I used the recommended grits for the random orbit sander, 40,80 and 120. They also sell a 32 grit but not anything in between the grits I used. The sander was rented from HD. The sander worked quite well with the exception that I thought it would remove more of the surface. After doing quite a bit more reading, I found a review on the random orbit floor sander and its inability to perform heavy duty sanding whereas a drum sander may be more efficient.

I used oil based stain from Minwax and used a cloth to apply the stain and to immediately wipe off the excess.

My suspicion is that I did not properly sand the floor and to do so I need to use a drum sander to get down to the bare wood. What would be the recommended grits that I should use? I believe they go down to 20 grit. If I start with 20, should I proceed with 40, 60, 80, etc.? Also, with a drum sander, does it do a good job with the finishing or is it recommended to do the final sanding with an orbital sander at the finer grit?

My last question is, since the majority of the floor has been unprotected do I need to clean the wood prior to sanding, such as with TSP? Or would this do more harm than good?

 
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12-08-06, 01:39 PM   #5  
Usually you can do 40/60/80. Go to www.nofma.org and click publications. Download for free the National Oak Flooring Manufacturers Association technical manual for finishing wood floors. It tells you in detail how to finish your floors.

 
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12-08-06, 01:54 PM   #6  
A drum sander does the best job of stripping/leveling a wood floor BUT it isn't very diy user friendly. Spend a few seconds too long in one spot and it may adverserly show in the finish.

Due to the age and the different type of wear/exposure of the flooring, I don't know if it is possible to sand enough away to make it all uniform. I do think a nice job can be had, maybe not with every stain color.


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12-24-06, 12:15 PM   #7  
What is the typical cost to hire a proffesional floor sander? I have all the molding removed and varnish removed. I called one local place and they said $1 per square foot.

 
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12-24-06, 12:30 PM   #8  
Cost of sanding by professionals tends to vary from area to area and among installers. Size of job is also a factor.

Many opt to hire the sanding done and finish themselves. This eliminates the worry about improper and inadequate sanding and sander marks in floor. Get at least three quotes. Ask friends and neighbors for recommendations. Check your yellow pages.

 
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04-28-12, 02:18 PM   #9  
factors that affect stain absorption

Very old thread however I would like to offer additional information to anyone who reads this thread in the future. Many important factors can affect stain absorption:
  1. The grit used to sand the floor. Coarser grit results in more absorption so an 80 grit will produce a somewhat darker floor than 320 grit, etc.
  2. Raising the grain by dampening the wood first will substantially increase absorption.
  3. A combination of sanding and raising the grain will maximize absorption even for a single coat of stain. Careful, the results can be significantly darker than expected.
  4. Pre-conditioning will often make stain absorption more uneven not less.
  5. Presealing (e.g. with a coat of shellac) then sanding can sometimes help even out absorption.

Use a couple of oak boards to experiment with various grits of sandpaper, raised and normal grain, and sealers or conditioners. It's an inexpensive way to make sure there are no surprises later.

 
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