Bleaching Hardwood Floors With Klean Strip To Remove Dark Stains From Dog Feces


We have 3/4″ Brazilian cherry floors which were installed unfinished and then sanded and sealed with Duraseal (by a floor contractor not by us). We requested the Duraseal because we do not like the look or feel of polyurethane and we have loved the way the floors look and feel. But in hindsight this may not have been a practical solution because we have 5 indoor kitties and 1 indoor dog. The little dog did had one big accident which has left a lighter stain on the floor but the biggest problem has been kitty barf. We must have 30 little stains in one or two of the rooms due to kitty barf which leaves dark stains or lighter stains (perhaps the color of the stain has to do with the PH of the vomit, I don’t know).

We were intending to re-treat the floor with Duraseal Renovator which is recommended by the manufacturer but we need some advice before we do that. Is there a way to remove those light and dark stains from the wood itself without re-sanding the whole floor? The floor itself has also gotten over all very dark. We live in a house with a bazillion windows near Savannah, GA, so we get LOTS of natural light. Instead of using the Duraseal Renovator is there another product besides polyurethane that will slow the floors from darkening and would repel the kitty barf too and still have the natural wood feel that we like? If it’s best to re-sand the floors entirely we would like to know at this point before we put on the Renovator.

Thanks for your help!!



Dear Charmaine

I’m going to assume that when you say Duraseal you mean you applied the DURA SEAL Penetrating Finish (Stain) in the neutral color 210. I’ve had some past experience with this material, and have long ago come to the conclusion that’s it’s not really suitable for hardwood floors. And the Renovator product gave us much less than stellar results when trying to renew one of these oil/varnish floor finishes.

Oil/varnishes are a newer version of the old China oil (tung) finish that was commonly used at the early part of the last century. Tung oil took over a month to cure so was supplanted by a faster drying oil/varnish like you have used. These in turn were supplanted by oil modified polyurethane and alkyd vanishes by the 1930’s.

The supposed advantage of oil/varnishes is that they are repairable. And seeing how the film build on the floor is almost negligible, that would be important. You see with only 2 coats of the DURA SEAL Penetrating Finish (Stain) you have only built a protective film on the floor equal to one diluted coat of oil modified polyurethane finish. That why you can still feel and see the texture of the wood. It may look nice, but it has little or no water resistance, and that’s what counts on wood floors.

Animal feces and urine stain the wood dark and the vomit like you said can actually bleach or stain the wood light or dark. I’m guessing that this is an alkaline/acidity effect, but I really don’t know my biochemistry. But bleaching is the key to removing the stains. Wood bleaches will only work when the wood is free from all finishes and waxes. I sure hope you haven’t used that renovator stuff yet. If you have you will need to remove it first with steel wood and paint thinner. Then hand sand off the finish.

While you are sanding the finish off, this will give you a chance to see how deep the stain is. If you are really lucky you can sand enough wood off so that most if not all of the stain out. Use 80 grit sandpaper, and finish with 100-120 grit. I will usually use a wood scraper for the initial removal, but will always finish up with hand sanding anyway. But you will have to learn how to sharpen a scraper to razor fineness before you use it on your smooth floor. That’s another subject for another time. Use sandpaper if you cannot sharpen a wood scraper well. Hand sanding just takes a little more time, but does the same job.

For any urine and feces stains that are dark, your only hope is to use hydrogen peroxide and sodium hydroxide, in a very strong and dangerous concentration ( 27% ). Klean-Srtip is one of these products that’s readily available in North America, and comes with good instructions. Visit their web site at for info on how to use this stuff. Oh, I just discovered that their web site is down for repairs, so you will have to call them to find a distributor of Klean Strip in your area. When their web site is working, click on the product button, then the wood bleach link.

You generally have to mix the two parts of these bleaches together, but this contains it own neutralizer, so only a washing up with water may be needed after. This type of bleach will always turn the dark spots to an off white color, which you will then have to blend in with a dark colored wood stain to match the color of your finished wood floor.

Bleaches are water based, so they will raise the grain and make the wood rough. Be sure to let the wet wood dry overnight. And do be careful when you sand it smooth the next day, so as not to sand out the bleached effect. Do the final sanding with just a little pressure and use 120 grit sandpaper, just until the wood is smooth.

Once the dark spot has been turned into an off white spot, you will need to re-stain the spot to match the tone of the Brazilian Cherry. You might just use the same Penetrating Finish made by Dura Seal but this time choose a darker colored stain. You could also try the DURA SEAL Fast Dry Wood Stain. They both come in a wide variety of deep and dark tones, so choose one just a bit darker than your floor. If it happens to turn the floor too dark you can always wipe it off more than usual, or use a bit of thinner to help wipe or simply dilute it. You may find that you have to apply it and let it sit for some time before the color sets in a wood as dense a Brazilian Cherry. Of course just try all this on one or two spots in an inconspicuous area.

Now as to the white bleached cat vomit areas, I would suggest you neutralize them first with a little vinegar, and a wash with a small amount of water. Oh, I forgot to mention that all these bleaches and washings will really harm the surrounding oil/varnish, it’s not very water resistant so use water sparingly and carefully. So anyway, neutralize the white vomit areas, let dry overnight, and fine sand the area (120 grit). Then just stain these spots with the Dura Seal stain, and hope for the best.

You can use an artists brush to control the stain better. And even try those touch up stain pens to repaint the grain lines that might have been lost in the bleaching process. You will need to buy at least 3-4 colored wood stain pens to match all the different colors lost in the wood. Try Lee Valley Tools. Here is the URL of their product.,190,42997

Once you have the stains re-colored and dry at least overnight, then you can touch up the oil/varnish floor finish. You can stay with the same brand of Dura Seal at least for the touch ups, and apply as many coats just at the same rate and dry times as your flooring contractor used. Even this stuff cross links (hardens) a bit, so it’s always wise to steel wool between all coats to get good adhesion.

If you are interested in a better, less toxic oil/varnish that has a much better film build than the Dura Seal you could try a product called Tried and True oil/varnish. While this is mostly used on furniture (because this lighter duty use is more in keeping with oil/varnishes in general) it should be better than Dura Seal because it is all oil with no toxic solvent thinners. But it will take at least 5-6 total coats of oil/varnish to give you some water resistance. You already got 2-3 coats on the floor now I only resume. So only one or two more coats may be needed to make a better more water proof surface. You might just try a small can (it’s expensive) of this stuff and do a sample spot on a high use area. See how it works for you. Here’s the URL of the Tried and True products.


The smell that goes along with urine and feces stains could be eliminated first or later, and for that I will refer you to the good folks at the Cleaning center at Don Aslett has written a good book about this very odoriferous subject, called Pet Cleanup Made Easy. You may find you have to use their odor treatments (their X-O treatment works miracles) before and after the bleaching. The odor may be coming from under the floor, on the baseboard and even on or in the wall in some cases.

The alternative to bleaching out stains is to repair them out. Click on the wood floor repair article (it’s free).

This is a must read before you begin bleaching the wood. You may find that if you have the basic carpentry skills, a wood floor repair of the stained areas suits you better. This is what most professional do, as we charge by the hour for repairs. We cannot always experiment with wood bleaches on our client’s floors. We must have a certain and predictable time to completion. And in our case removal and repairs are often the quickest way to go, but not always the cheapest.