refinishing 80 yr old fir floors


I am refinishing 80 year old fir floors. There are some bruises that are quite pronounced and round (probably from furniture feet, like beds). I've done a lot of reading and I've tried things I've thought of, but so far they resist most of my efforts.
Read: sand 45 with coarse grit rotating 90 until gone then finish with grain.
Result: I seem to be using a lot of good floor to get rid of blemishes. It seems it would be better to address each blemish on its own or I'll loose a lot of my boards' depth.
My thoughts: using heat gun remove most of the shellac/varnish and then it's easier to hand sand, but it makes a hollow.
Question: Can I fill the hollows with a "filler"? Can I mix a filler using my sanding sawdust? Is there a commercial product that will finish like the rest of the floor after I stain it all?
TIA
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glassartist wrote:

That is the unfortunate fact.

Whether the hollow or blemish would be worse depends on the situation.

Possibly, probably not. Most of the times the blob of filler looks almost as bad as the blemish. You can use artist brushes and apply stain to the filler to replicate the wood grain. Easier said than done.

Sand the floors most of the way done. The blemishes and divots will stand out as you'll see the remaining floor finish and the flatter areas will be sanded bare. Hand scrape the remaining finish off a low area. Wet a rag, wring out a bit, lay it on the low spot you want to raise. Do not saturate the wood. Try not to go outside of the low spot with the water/rag as that will create other problems. Move a hot iron around on the wet towel. This will raise the wood. It works most of the time, but not all of the time. It works best on more or less uniform depressions. Let the wood dry for a couple of days at least. If you're in a rush, hit the treated areas with a heat gun or hair dryer (longer blowing time is better than hotter temperature). If you have a moisture meter, so much the better. Finish sanding the floor.
In general a refinishing eats up somewhere between 1/16" and 1/8". All of these decisions come down to cost. Do the best thing for the floor that you can afford and I'm sure it'll be the right thing to do.
R
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If this is an old floor in an old house leave some of the character there. I'm in the process of doing a 150 year old victorian that has fir floors and I'm going to keep some of the blemishes, I've filled the holes with plugs that I cut, nothing fancy and will not be putting filler between the cracks, it's part of the look and feel. Just smooth them out and stain.

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Thank you for your remarks. I think that is good ole common sense answer. I get caught up in trying to make things "perfect". I love to see the whole project come together and feel "right". I think leaving some character is a good idea. I have two boards near the wall with big soft rotten spots (no idea why either), that I'll replace. Thanks All.
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Since I'm doing my whole house I'll pass on some more information. After doing a large master bedroom (Size of living room) myself that total cost of the materials and rentals was $400, I am now getting the rest of the house done by a pro including the stairs (runners and sides) for $2200 with tax. It might be worth just calling the pro. I figured the rest of the house would have cost me more than that to finish myself.

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I have heard of spotting water into dents to cause the wood to swell back towards its origional shape. It could be worth experimenting. I'd sand the finish off the dent, Apply water to just cover the dent, and see what happens.
Bob
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