Q: One visitor asked, "I recently had the hardwood floors in my 1950's house professionally refinished (sanded, stained, and polyurethaned). The floors were previously covered with carpet and had some stains, thought to be from carpet cleaning chemicals. A couple months after the floors were refinished, white spots on some areas of the first floor started appearing and keep on getting worse. The floor is above a crawl space. The contractor said he thinks it's from moisture; however, not all areas are affected and it seems the white spots are in the areas that were previously stained." - from an Environmental Scientist
You are a scientist and are asking me this question? Thanks!:)
First, I don't recall ever seeing staining from carpet cleaning chemicals, except that around the perimeter, the moisture will cause black rings around the nails of the smooth edge that holds the carpet in place. Other than that, I have never seen "stains" from carpet cleaning on the floor in general. None the less, such chemicals would be or can be a concern. If it cannot all be removed from the floor, how will it react with the solvent based finish? It is likely that such finishes will "activate" existing residue from old finish or cleaners.
I have seen white spots in the past with products that are not compatible when not fully cured and mixed together. Are these light areas on the board joints or all over the surface?
Since this floor is over a crawl space, do you have this area vented and covered with a tarp? How far above the ground is the floor? I don't suspect this is a problem with moisture at this point. If it was, the floor would swell and cup! Wood always expands or shrinks with more or less moisture. So, I think this must surely be a chemical reaction between incompatible substances. As the workers went through the process of sanding and finishing the floor, did they allow sufficient time for each coat to dry? Given that there is a crawl space, it is likely cold under the floor. So, each of the products would likely require longer dry times, for stain and finish.
Related questions about wood floor repairs:
Cracks, Dents and Scratches
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>How to touch up indentations from dog's claws (on maple floor)?
>Should I fill in deep gouges?
>How to fix a piano made gouge?
>How do we blend in nail heads that are sticking out?
>What can we do about these 1/2" gaps?
>How do I remove staples from the floor?
>How do we remove scuff marks from our floor?
>What are signs of termite damage on my hardwood floors?
>I have deep gouges in my stair treads and risers. I used a putty filler and then stained some of the stairs only to discover they are still quite visible. Is there anything to do to make these marks blend in with the rest of wood?
>How can I remove the cigarette burn mark on my wood floor?
>There is some termite damage in almost all the boards of our new homes floor. I want to know if I could use wood filler over these spots or maybe even the sawdust and glue.
>Our problem is that the flooring seems to have lots of cracks between the boards and somebody in the past put a lot of NAILS in the boards in the hallway. Can we putty this or is there a better way to repair it?
>No gaps have developed anywhere on our floors, save an 8ft run betweentwo planks in the kitchen. the gap is 1/8th of an inch (A nickel fits inside of it). How can we repair this and still have the floor look great?
>If space between planks is wide can these gaps be filled without ruining the "look"?
>How do I silence the squeaking of our hardwood stairs?
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>Something heavy was dragged across floor and left a mark. How do we fix this?
>How can we fill the 1" cracks between the boards of our floors?
>Does a 3/16 variance over 10 ft. span for 3/4 thick cause creaks?
>How do I remove the staples in my floor and what do I fill the holes with?
>Our floor is making some creaking noises in some areas. How can wefix this?
Cupping and Leveling (& Blending 2 surfaces together)
>Our floor was put down in the summer and this winter it buckled along some of the seams, I think it was due to the cold winter (-35c) that we had.
>I've installed hardwood in my living room. There are some uneven transitions from board to board. How can I fix this?
>My floors are not even due to settling of the houseover the past 50 years, is it a problem refinishing them or would it beOK?
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>My maple floor gets a hump in it every humid summer, what do I do?
>How do I eliminate the air bubbles under our new laminate floor?
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>We have an area approximately 15" x 20" that is not level. Is there any wood floor product (epoxy, urethane) that could actually be poured into this "valley" in our floor and would dry level with the clear finish that the floor already has?
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>Could we level our own floors?
>Is it possible to sand particle board where it is buckled with a belt sander?
>We have light areas on our floors where we once had rugs, how do we blend them in?
>How do we fix the yellow spots where the carpet covered the hardwood?
>I recently had someone come to my condo to replace a section of my laminate flooring. The new flooring ended up being about two or three shades lighter than the old. Is there any way to darken it without replacing it?
>What can I do about the uneven color, lighter and darker shades, on my floor?
>Since our maple floors were installed, we have noticed that there are patches where the colour of the flooring is much lighter than other areas. Is it oxidation?
Spills, Residues and Stains
>Some snow or water got into the pipes and dripped creosote onto our wood floor!
>After removing an old carpet I discovered paint had been dropped on the hardwood floor in several places. How do I remove it?
>Is there is any way I can remove the paint off door trim without removing the stain also?
>How do we repair water damage?
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>How do we remove the stain from the plaster that dripped onto our stair treads?
>How do we remove this glue residue from our floor?
>We have a water stain. The previous owner left some oak sawdust for hardwood floor repairs. How do we use it?
>How do we remove dog pee stains from stair treads?
>I have a dark spot on my hardwood floor which came as the result of my dog urinating on the floor. How do I remove it?
>we removed carpeting to find that pet stains have penetrated our beautiful hardwood floors - some areas are very dark, other areas appear almost "bleached" out. Do you have any suggestions on removing or lessening the stains?
>How do I remove or hide brown circles?
>What kind of bleaching can be used to remove dark pet urine stains?
>The hardwood floors in the upstairs portion of the house that we bought has been speckled with paint. How can we remove it?
>There are some black spots on our hardwood floor. How can we get them it out?
>What do we do about the white spots left from the white stain we sanded off?
>Only the first coat of paint on our pine floor is removable with chemical stripper. It is possible that an epoxy paint was used underneath. What can be used to remove epoxy paint from wood?
>What can be done to remove this glue/carpet/mess residue? Any chemicals capable of not damaging the poly finish of the old hardwood and at the same time remove the glue?
>How do I get carpet underpad off our wood floor?
>My old farm house has painted wide plank pine floors. What would you recommend to remove the many layers of paint?
>Do strippers need to be neutralized with mineral spirit?
>Should we apply polyurethane over peeling paint?