3

Similar to this post, so apologies if it fully overlaps and I'm just misunderstanding.

I used sanding & oxalic acid to lighten / bleach out a dark cat urine stain from our 1952 hardwood floors (wood species unknown, San Francisco Bay Area, California, USA. Redwood is common around here). In the past-owner-inherited DIY cupboard there's a can of Behrs transparent oil based polyurethane, and a small can of water based polyurethane, also clear finish. I presume these are to seal the surface after staining. I therefore presume we're missing a stain to colour this wood, but unlike the top-linked post, I presume I've bleached the natural colour out of the wood, and therefore I might not be looking to add natural stain to a specific species, I might be looking to add a specific stain colour to match what the natural wood should be, and then seal?

IF that's correct, how would I go about colour-matching? I'm not aware that we have any unfinished test pieces of the same wood, nor removable finished pieces I could take to a paint store (or somewhere else? Home Depot?).

Many thanks in advance for any intel. Also bonus question: is there any chance that the stain and/or sealant/finish would bring out the luxurious dark colour of the cat urine that I've mostly removed?

cat_urine

4
  • 1
    Think it will be very difficult to do good enough to be not noticeable(to match the rest of the floor). Your local flooring stores might be able to give/sell you a few small pieces to test stains on, will need to repeat what you did to remove the cat stain first. Can maybe get a close match with staining, but think after you might want re-locate furniture/throw rugs. Do one coat of stain and wait, repeat as needed till a close match.
    – crip659
    Commented Jan 30, 2023 at 0:47
  • 3
    One question per post, please. Not that the removed question was largely a matter of opinion, and off topic here anyway.
    – isherwood
    Commented Jan 30, 2023 at 13:43
  • 1
    I've noticed that wet wood looks a lot more like poly'd wood than plain clean dry wood. Once dry, you might want to gently wet the stain area with water to simulate the increased contrast and saturation that your poly will add. After testing, put a fan on the test spot to dry it quickly.
    – dandavis
    Commented Jan 31, 2023 at 10:16
  • Sorry Dan, just to make sure I'm understanding you correctly: splash a bit of water on to get a rough impression of what it'll look like after I've done the polyurethane?
    – dez93_2000
    Commented Jan 31, 2023 at 17:43

2 Answers 2

9

It is going to be very difficult (on a really good day) to color match that and smoothly blend it in along the edges so that nobody knows that there's been a "patch" there.

Matching stain is an artistic endeavor and will take time, patience and trial and error. Even if you have a can of the original stain with a sworn statement from the previous owner that this is exactly what they applied to the floor, the stain on the floor will have faded over time from what was originally applied, so a fresh application will still stand out. Additionally, the wood has been lightened by the cleaning process, though it hasn't been evenly lightened - there's still a dark spot in it and that will definitely telegraph through any sort of intentional staining process.

Ideally, you'd work on some scraps of wood from this project, apply various colors to find something that's similar, then if necessary, apply a second coat, or possibly a different color. Lather, rinse, repeat (keeping good notes on every sample) until you've found a satisfactory process that will get you as close as possible to the current color.

Since you don't have that luxury, you're going to have to work "live". I would suggest that you start with a very light color stain. You could apply it straight from the can as the manufacturer recommends, or you could pour some out into a pot and thin it with the appropriate thinner (water or turpentine/mineral spirits) and wipe it on, let it sit a few minutes, then wipe the excess off. Let it sit and dry for several hours, then look at it from several directions under natural light (looks like there's a window close by) and only artificial light (close the blinds or wait for night time).

You'll want to patiently repeat this process - if you get too much stain on too quickly, or start with too dark a color, you'll end up with this area being too dark, and your only options will be to live with it or to sand it off and start over. Again.

You'll have to eyeball the finish level to your satisfaction. It's possible that you may put one coat over the whole thing, then two or three coats between what you've sanded out and where the stain is. You'll also have to mentally adjust for the fact that the currently finished floor has a clear, glossy top coat of some sort on it, while your work area does not. This gloss coat will change the apparent color of the repaired area and will make it more difficult to accurately judge the final color.

You may have to apply a coat of stain, then immediately use a rag with some thinner on it (again, water or turpentine, depending on the type of stain you're using), wipe along the edges where it blends with the existing finish to "feather" the edges in to avoid a hard line between existing finish and new finish.

Also, since the stained spot is darker now, it's going to be darker once the finish has been applied. The good news, IMHO, is that it's somewhat subtle and it doesn't have a hard, defined edge. I think you'll probably just have to live with it and think of it as a natural discoloration in the wood. If anyone asks, call it "character". :)

Do note that it's possible that there has been no stain at all added to the wood and that the color you're seeing as a finish color is simply a few coats of a clear, gloss finish followed by the natural warming of the color of the wood as it's been exposed to light over the decades.

This may be a case of "do your best", then throw a rug over it or put a piece of furniture there to hide it so it doesn't bother you. Then it's up to the next owner to decide if it bothers them enough for a full refinish.


This is a DIY site and I strongly encourage and support the DIY effort. However, this may well be a case for hiring a professional. Personally, I do not have the artistic ability to judge colors all that well, nor do I have the experience to be able to mentally add a gloss top coat and know how that's going to change the apparent color of the finish. You might want to consider finding a couple of wood finish restorers (you might try a search for "antique restoration" or "wood preservation") in your area and ask them out to give a quote to do this repair. You may find that the price is painful, or it might be surprisingly reasonable, but in either case A) you'll know, and B) you'll have an experienced, artistic pro giving you an idea of what's involved. You can always turn them all down if it's too pricey and you decide to do it yourself.


Another option would be to sand down the whole floor and refinish the whole thing. Obviously, that makes this a much bigger task that will take more time, effort and money, but will make all but the stained spot itself disappear since the whole thing will be finished all at once.

This is the "nuclear" option and would probably be the last resort if you simply cannot get the repaired area to "disappear" to your satisfaction.

3
  • 1
    I was thinking similarly. Furniture repair pros sometimes have to do this kind of color matching; might be worth asking one of them for advice or quote.
    – keshlam
    Commented Jan 30, 2023 at 13:42
  • Thanks so much for the excellently detailed answer. Would you think this [lowes.com/pd/… would constitute a suitably light stain? As you say, perhaps cut with mineral spirits? As @Olivier says, after I've feathered by sanded edges? FWIW the spot is under the cat box which is now protected by a waterproof mat, so it's only very rarely seen when we move things around to have guests over - good enough will be good enough!
    – dez93_2000
    Commented Jan 30, 2023 at 18:07
  • 1
    It may be worth getting a similar piece of wood to experiment with (looks like oak to me). Especially as you do not want the stained floor to match, because the finish will darken the color some more. Eyeballing this is very difficult, even if you've done it before. If you haven't, definitely try on some other wood to learn how everything behaves.
    – Olivier
    Commented Jan 30, 2023 at 19:21
3

The woodworking SE would probably give you a better educated guess but my impression is that there was no stain involved. Just a clear oil based finish which has aged.

Try feathering out your sanding a little so the existing finish doesn't end as sharply. Then add a coat to a small corner and see how it looks.

Keep in mind that you can sand it again and start over but removing stain if you make it too dark is not as easy.

You may end up having to pick between "looks similar now" (with stain) and "will look similar in a few years" (as the finish ages).

7
  • 1
    I'm not an expert, but I'd think that you'd want "looks similar now" for today's result. Both new and old finish will age and if they don't match today, they won't match in the future.
    – FreeMan
    Commented Jan 30, 2023 at 16:16
  • 1
    @FreeMan I would expect the change to slow down, such that they would get closer over time. But I could be totally wrong about this, my experience with oil based finishes is mainly removing them.
    – Olivier
    Commented Jan 30, 2023 at 16:58
  • Thanks for this. I suspect you're right that it's previously only had an oil-based finish applied. But do you think that adding a coat of this will match the colour? (I presume by "add a coat" you mean a coat of oil based finish? Or do you mean stain?). My suspicion is that by my having bleached out the natural colour, adding just a clear finish will just make the bleached colour shiny?
    – dez93_2000
    Commented Jan 30, 2023 at 17:49
  • 1
    @dez93_2000 It won't match exactly but may be acceptable, depending on your tolerance. And yes I meant a coat of oil based finish. If you want a better match, see FreeMan's answer and be prepared to put a lot of time into it.
    – Olivier
    Commented Jan 30, 2023 at 19:17
  • 1
    @dez93_2000 you might find that your existing, worn floor is no longer quite "hi-gloss" but otherwise I can't think of anything. Think about letting us know in an answer what you do and how it turns out. Might help others later. And to answer your bonus question, yes the dark patch will likely become more visible again.
    – Olivier
    Commented Jan 31, 2023 at 0:35

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.