My Deck Stain Turned Black 4.6/5 (42)

This post was updated on March 1, 2022

Why Did my Deck Stain Turn Black?

We appreciate it when people write in and ask for advice when something goes wrong during their deck staining projects. Today we talk about what causes your deck stain to turn black after a year or two and what to do to get rid of the problem. We appreciate your input, so feel free to leave a comment below with pictures of your deck stain projects.


Moldy Deck

Black  Deck Stain

Why Did Your Deck Stain Turn Black?

Many things can happen to a deck stain when it is not applied or maintained properly. The biggest reason for a deck stain turning black is mildew. All wood surfaces need to be cleaned correctly prior to staining. The use of a quality wood cleaner and pressure washer or scrub brush is necessary to remove all the contaminants like dirt, grime, mold, mildew, and graying.

When contaminants are left in the wood pores and stain is applied a whole host of problems can occur. Mildew can begin to grow underneath the deck stain, which causes discoloring. This can also lead to rot and decay because if there is mildew there is also moisture present.
Another reason your deck stain turned black can be from using an inferior stain. Cheap quality deck stains do not contain the mildewcides and inhibitors that more quality deck stains have. The mildew or black discoloration can occur on top of poor-quality stains. Some low-quality deck stains can even be the cause of mildew infiltration. Some cheaper deck stains can actually cause mildew to grow in certain conditions.

To cure a deck that has turned black you will need to strip the wood using a quality wood deck stain stripper or wood deck cleaner. Remove all the old existing deck stains along with any graying, mildew, and other contaminants. Wash the deck several times if need be. Once all the wood is clean and allowed to dry for several days, apply a quality deck stain that contains mildewcides and mold/mildew inhibitors so the darkening of the stain does not reoccur. Proper maintenance should include a light wash every couple of years followed by a recoat of the same quality deck stain.


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Maura
Maura
2 months ago

HI, Is it possible that splatter from a bluestone stoop is causing staining on a douglas fir porch? The deck was treated with penofin. The splatter marks come after heavy rain. The porch is covered.

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lori
lori
4 months ago

Hi I just stained my new deck waited one year before doing so, I used the cleaner and brightener first then one coat of stain, then it did rain hours later which was not suppose to, but a small part of my deck is a little darker than the rest, should I put another coat on the part that is lighter so it will match? It really did turn out good but now I’m not happy with the look since one part is little darker.

Mary Janusz
Mary Janusz
4 months ago

We just had a fir tongue in groove porch floor installed. It was stained & sealed with Ready Seal and looked good for 2 weeks. It rained on Thursday night and the deck is black (see attached picture). Our poor builder is ready to rip the floor off and start over. Thank you for any help you can provide.

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Lina
Lina
6 months ago

Hello, Scott. Thank you for giving us this forum. We are in the process of re-staining our deck. We just finished sanding it using an orbital sander and detail sander. Then we power-washed it and dried it with clean rags, using a bit of pressure while wiping to remove any remaining dirt. Would you recommend that we proceed to stain or should we wash the deck with a deck cleaner then follow with a wood brightener? This is our first time doing this so we want to do get it right. I’ve attached a couple of pictures for you. Thanks in advance for your input! We really appreciate it!!!

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Lina
Lina
6 months ago

We used 80 grit. I just poured a drop of water and it beaded on the surface.

Lina
Lina
6 months ago

Thanks, Scott. I tried staining in an inconspicuous area and it looks like it took the stain provided that I applied with a brush (back and forth motion) then wiped off the excess with a clean cloth. Do you think I should still wait a couple of months? Can I try staining it now and if it doesn’t last, clean and brighten in a few months then re-apply the stain? Thanks again for your input. This forum is really helpful.

Lina
Lina
6 months ago

Thanks, Scott! I will do that. Have a good rest of your week.

MarkyMark
MarkyMark
1 year ago

Hi, I found your site too late it seems. I heavily pressure washed my deck to strip off the old stain. In the process I damaged the surface slightly in few places. I belt sanding most of the rough spots. It seems to me my deck is very clean now and most boards look bright, but I have a few darker boards standing out. These have move cracks and have a slight bulge. Can you tell from my photos whats up with these dark boards ? I plan to put Flood solid stain (light color). Since I heavily pressure washed my deck, do I still need to use a cleaning solution and/or a brightener ? Thank you so much and thanks for your informative site.

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MarkyMark
MarkyMark
1 year ago

I see you recommend a brightener. Do i need a brightener in my case of ‘over’ pressure washing ?

MarkyMark
MarkyMark
1 year ago

Thank You!

Linda
Linda
1 year ago

I used Penofin Step#2 and pressure washed our Tigerwood deck and oiled with Penofin Hardware Oil Natural. After seeing my deck turn black I am thinking I need to completely re-clean and start over, but obviously not using Penofin products. I will state that not all of my wood had original color prior to oiling so maybe I needed to use more cleaner? However, even on the wood that was very clean and dry turned dark. Can you please provide me steps I need to take and best product to use? I wish I would have found this site prior to starting. Thank you! Not sure my photos attached.

Marie
Marie
1 year ago

Why is my decking looking this is. I have now used red label to strip the Ron seal deck stain off. It was put down last year and just looks dirty all the time.

Susan
Susan
2 years ago

We have Penofin red label on our deck for 3 years. It has darkened the most where exposed to the sun. We don’t want another coating of the Penofin. What can we use instead?
Thank you!
PS We don’t want to sand the deck.

Alysha Barber
Alysha Barber
2 years ago

Help! I have this big mark on the deck next to the wheel… The rest is grease marks from a bbq, not sure if this is the same or something more suspect?

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Alysha
Alysha
2 years ago

Do you think that all of it is grease stain?

Marvin
Marvin
2 years ago

Can the moisture causing the blacking of the deck be underneath the deck? Lack of air flow under it?

Bob
Bob
2 years ago

I have installed red cedar clap boards with the rough side exposed some 15 years ago on my house. I applied Penofin Ultimate Premium Western Red Cedar oil stain shortly after installation and reapplied the stain over time. The cedar clap boards did turn black. I prefer not to go through the process of the stripping process before reapplying more stain. Can I use TWP (oil) 1500 Redwood to the already Penofin stained clapboards to lighten the color? I am also concerned that the two products are not compatible. Thank you

Jen
Jen
2 years ago

Hi i was reading up Penofin stain. So you guys dont recommend them anymore? I lice in Canada and TWP, AC and Defy do not have a dealer here. We do however have Penofin. If you dont recommend Penofin, what orher products can we use aside from above mentioned product. I understand we will most likely need to re-do the sealing more often. Thanks.

JIM
JIM
2 years ago

older redwood deck use oil or water base stain

Cindy
Cindy
2 years ago

I had my pressure treated wood deck repaired, cleaned, and stained a few months ago. Now many areas are black. Did the company I hired do something wrong? Anything we can do?
Thanks!

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Cindy
Cindy
2 years ago

Thanks! Normal for stains and mildew so soon after staining? How can we remove without harming the deck?

Cindy
Cindy
2 years ago

Is it normal for stains, mildew, etc so soon after staining? What is best option for cleaning without damaging wood or stain? Thanks!

Michael Motruk
Michael Motruk
2 years ago

I have black dots over half of a brand new cedar floating dock for I built for our pond … it’s been in my garage since Mother’s Day I just pushed it out Friday July 17th, it rained on it Sunday, Monday morning black specks all over half the deck… it has not been stained or treated with anything….is it mildew?? I tried power washing it out with no luck it sanded out a little but not easily. What can I use to remove the specks??

Thanks Michael M

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Mike
Mike
2 years ago

I thought I was doing everything right restaining a cedar sided house. It’s originally stained with Penofin Transparent Cedar red label and I am applying the same thing.

The house was last stained probably 5 years ago, working on the south facing side, the cedar has lots of black or dark patches at the bottom of the vertical cedar siding. The upper 2/3rds is in relatively nice shape still.

My prep-
Using Penofin Cleaner – dissolving in water and applying with a pump sprayer, letting it activate for about 20 minutes and then scrubbing the surfaces, doing a second application on the lower areas that have the blackest staining. Hosing off with garden hose

Using Penofin Brightener – dissolving in water and applying with a pump sprayer, letting it activate for about 20 minutes and then doing a second application on the lower areas that have the blackest staining. I can visually see the dark areas lightening during application. Hosing very thoroughly with power sprayer, making sure not to damage the wood, but enough that some mushy wood fibers are showing up and being washed off during the spraying.

Letting dry 24 hours.

The surfaces look great, much lighter, black staining gone, cedar looks almost brand new.

Reapplying 2 coats of Penofin red label. However, this is where I am having the problem, as soon as I apply the first coat, the darkness at the bottom if the cedar, very ugly seems to reappear. The nice bright even surface is dark again at the bottom as if I never did any prep.

I stopped, only covered a small section with one coat, I don’t want to go any further until I know what steps to take, or is it possible the wood is so old it’s just beyond coming back to like new?

Picture below -shows before, after cleaning, after restaining

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Mike
Mike
2 years ago

Hi thankjs for the quick reply. I’m confused, what are “internal water stains”?
THanks

djsmith
djsmith
2 years ago

Hi,
Sept. 2019, I contacted Rustoleum to report the Deck Restore product, with a limited lifetime warranty that I purchased through Lowe’s, was all peeling off. They first tried to offer an inferior stain to repair the surface. I finally got to David Summers the product manager for Rustoleum. His final offer, after working this issue for months with Rustoleum was to refund the purchase of the product, purchased 8 years ago, if I have the receipts, or they provide a product replacement with no future warranty. I cannot get all the old product off with a pressure washer, and it was too late to apply, as the temperatures are too cold for the product to set. My only option is to replace the deck floor. I asked for Rustoleum to cover material only, and he indicated a limited warranty only covers the Restore Product costs. I am still working this with Rustoleum and wish there was a current class action suit. All I wanted was for them to provide their current similar product for me to cover the deck and extend the warranty for lifetime. They refused.

Beth G.
Beth G.
2 years ago

Hi there. Had brand new deck installed 7 months ago ( treated wood). Read multiple articles on your site and prepared wood with Restore-A- Deck products and then ordered recommended good quality Armstrong Clark wood stain. 3-4 months later noted black residue on the surface of the deck, currently so bad it almost leaves marks on the soles of my feet when walking barefoot. Not even full year and deck has completely different color even though good products were used and followed all instructions to prep and stain. Located in NJ.
I was planning on cleaning the deck in the summer and restaining with TWP instead? Not sure what happened but it looks bad.

Marc
Marc
2 years ago

Hi there. Thanks for all the great advice on this thread. I’ve just had my deck sanded and re-oiled. It was last oiled about a year ago and was definitely ready. They sanded and applied three coats in one day, and now checking it the next day there are lots of black marks in the wood. Could you advise on what this is from and how to fix it? The wood is Ipe. Thank you!

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tabitha
tabitha
3 years ago

Brand new cedar deck has all these black leopard print like splodges all over it. It appeared after the first rain. No metal sanding as been done anywhere near it. No railings even installed yet! Almost looks burnt in places. This is a professional install.
Any suggestions?!

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Jackie McCanm
Jackie McCanm
3 years ago

Hi – this is my merbau deck that was put down 10 months ago. It has gone black apart from area that were covered with furniture? Any advice on best way to deal with this? Thank you Jackie. ps please ignore one picture there it’s my fence- sorry can’t work our how to delete it now!

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Hayden
Hayden
3 years ago

Just wondering what these black marks are

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Hayden
Hayden
3 years ago

I don’t have a metal gate
The deck is only one week old

Hayden
Hayden
3 years ago

How do I remove it

Hayden
Hayden
3 years ago

I just had my spotted gum Deck done last week
After I hosed it all down black spots appeared not sure If this is normal
Anykne got some advice with this matter?

Jackie Walth Duchscher
Jackie Walth Duchscher
3 years ago

Hello,
Our deck went without staining or 4 +/- years. I bought Sherwin-Williams Revive and cleaned, scrubbed and washed/power-washed the deck. After drying for 48+ hours I applied Sherwin-Williams Superdeck oil based stain. We have no nearby trees/shrubs. The deck showed no black spots prior to staining. It was just dry. Can I fix this by applying another brand of stain?

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Jackie
Jackie
3 years ago

Thank you.

Kyle
Kyle
3 years ago

I have what is probably a dumb question here. I stained our porch last Summer and after a year of taking a beating from the weather and foot traffic it’s just dirty and need some minor touch up in a few areas. Should I just hit it with a deck cleaner to make the appearance better? Should I use a cleaner and brighter to help the appearance? Again, just a few touch up areas I would like to hit with a brush. Thanks for your advice (again).

Jim
Jim
3 years ago

I have an old deck, previously stained. Cleaned it with a deck cleaner (scrubbed with a brush, rinsed), then let it dry for 48 hours. Moisture meter showed less than 15%. Applied a coat of Cabot Semi-Solid stain. Unfortunately, an unpredicted rain occurred overnight, about 12 hours after application. Let it dry for about 10 days. During that time, have had rain every 2-3 days. The deck now is dry to the touch, but some areas have dark, shiny streaks (see photos). These boards also collect water more than other areas, so I suspect that the stain may have been over-applied. Is there a way I can clean up the dark areas without having to re-do the whole deck?

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Jim
Jim
3 years ago

What do I have to do to make sure the black doesn’t come back? Will a deck cleaner be enough or do I need to strip or sand it?

Cindy Brown
Cindy Brown
3 years ago

I had my deck sanded to the bare wood. Then I used a brightener twice and let it dry completely. After mucho research, I chose the Armstrong Clark stain and applied one coat which looked okay. It dried and after a couple of weeks I applied a 2nd coat. The deck has turned black from what I suppose is mildew even though this stain supposedly has a mildewcide. I have not idea what I could have done differently. I was very careful to follow directions for each step. I’m disgusted.

Ken
Ken
3 years ago

I used an oil based sealer and stain when applied it was hot and humid it took forever to dry

Chris
Chris
4 years ago

We had built a deck three years ago, stained it the second year. There is a tall birch tree over my deck. Our patio is black this year. We used deck cleaner, some came off, some didn’t….Now what to do? Any suggestions? Do i go with a darker stain? My color before was Honey Gold! Have a great day!

BCS
BCS
4 years ago

Thompson’s waterseal immediatela
y tuned my redwood deck black. Why?

Bill
Bill
5 years ago

Beware of Penofin. Check GOOGLE for others who have had disastrous results. I sanded my cedar deck to bare wood and used Penofin Marine grade top of the line stain. 3 months later dark grey. Sanded it down again same results. Sanedebdown again same results. After 3x I gave up.

john g. mcmaster III
john g. mcmaster III
5 years ago

My deck turned black.I applied a cleaner and have pressure washed it several times. Ther are still small stains here and there which only seem to come off when pressure washed so close the wood is in danger of being damaged. I have even tried brushing. There seems to be no end to it. I live in a warm humid environment. The old stain is gone now,but the marks are there. During pressure washing, it seems that I remove them. After drying, there are always some left. I am at my wits end.

SCM
SCM
6 years ago

I had a deck renewed last year. All verticals were in OK shape and were re-stained with a solid stain. All horizontals were replaced with new cedar and stained right away with Flood semi-transparent. A year later the horizontals were black in areas that were exposed to the elements, but still OK under chairs, etc. We tried scrubbing the horizontals with bleach and plastic brushes, which removed the black but also most of the stain (not all). Now it has been mostly unstained for about 3 months waiting for a break in the local rain. A contractor’s suggestion is to sand the horizontals and apply new stain. I’m cautious about using a stripper because I don’t want to remove the solid stain from the verticals, since it still looks great. What combination of sanding, stripping, and/or cleaning do you recommend before applying a new stain to the horizontals? Also, after this process, I’m thinking of using either TWP 100 or Armstrong Clark. Do you prefer one over the other in this case? I’m in central Texas, and the deck gets plenty of sun.

RJH
RJH
6 years ago

have vertical pine vegas on exterior of southwestern home now have black streaks tried dilute clorox with some improvement. what should I do before re staining. should I use the deck cleaners mentioned?

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