This post was updated on April 4, 2025
Hello, I am Scott Paul, a leading exterior restoration contractor and business owner with over 30 years of experience in exterior deck cleaning. My wood deck cleaning help tips are based on my history as a wood restoration contractor and actual hands-on testing. See here for more info about me.
How to Fix Black Spots on a Deck
At DeckStainHelp.com, we receive this question frequently—roughly 50-100 times per year. Many homeowners are puzzled when black stains form around nails or beneath metal furniture on their decks. The main culprit? Rust. When metal rusts, it can turn black in wood, leaving unsightly stains.
Causes of Black Rust Stains on a Deck
1. Nails Rusting on a Deck
While rusting deck nails aren’t extremely common, it does happen. The two main causes are:
- Non-Galvanized Nails Were Used: If the original builder didn’t use galvanized or stainless steel nails/screws, the nails may begin to rust over time, leading to black stains around them.
- Protective Coating on Galvanized Nails Wears Off: Even if galvanized nails or screws were used, their protective coating can wear down over time, leading to rust. In some cases, power sanding the deck may remove this protective coating, exposing the metal and accelerating rust formation.
Nails Rusting On Deck
2. Metal Furniture or Grills Causing Rust Stains
Another common source of black rust stains is metal patio furniture, grills, or other metal objects that have been left on the deck for years. If the metal begins to rust, it can transfer stains to the wood.
💡 Prevention Tip: Opt for aluminum or stainless steel furniture to reduce the risk of rust stains on your deck.
How to Remove Black Rust Spots from a Deck
The best way to neutralize and remove rust stains is by using a deck wood brightener. This treatment will restore the natural color of the wood and reduce the appearance of black spots.
However, this will not prevent the rust from returning—especially if the nails or screws are already corroding. To permanently fix the issue, you may need to:
Replace the Rusting Nails or Screws
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- Remove old rusted nails/screws and replace them with stainless steel or galvanized screws.
- Be cautious—removing nails can damage the wood, so take your time
Deck Nails Rusting
How to Brighten a Deck (Video Guide)
Want to see how easy it is to brighten a deck and remove black stains? Check out this video:
📺 Watch the Video: How to Brighten a Deck
Have Questions About Black Spots on Your Deck?
If you need help removing black stains from your deck, leave a comment below with your question. Feel free to upload a picture or two—I’d be happy to help troubleshoot your specific situation!
Our IPE fence has black rust stains from the nail, our contractor mistake. We have tried cleaning / brightening and power washing, it did not come out. I guess there is no solution for it based on experts on my research. We have used messimers natural stain. Should we stain in a darker color so less of an eye sore? Any other recommendations?
You cannot blend in rust black stains with your wood stain. It will show no matter what,
Is there anything we can do to address this?
Your best option to cover would be a solid stain but we would not suggest that for IPE.
Try a darker color semi-transparent to see what happens. Maybe it will be better. Armstrong Clark in Black Walnut. Samples here:
https://www.armstrongclarkstain.com/samples
Why was my question and statement posted 9/7/2022 removed unanswered?
No idea what you mean?
My original question / statement is back up below this reply. It was removed for awhile after I posted it. My question concerns having no black rust marks on my deck prior to or even during cleaning brightening process with Restore A Deck they showed up a few days later after rain stopped before I could stain. Deck is 14 months old and had no marks whatsoever before using that cleaner/brightener combination. The black rust marks are around all the deck screws and since they were not there before cleaning how could the cleaner not be the cause? Thank you
Comments are not removed, they have to be approved after posting. This is explained after you post every comment.
No, a deck cleaner is not the cause. It is not aggressive enough to remove a galvanized screw coating.
I had zero marks around my 1 year old unstained pressure treated lumber deck until I used Restore A Deck cleaner and brightner. It rained for two days and when rain stopped today I see the black marks around the deck screws. This deck has been rained on and snowed on (Central New York even used ice melting products in winter on small section of deck) for 14 months and there were absolutely no marks around any of the deck screws, in fact, they were barely visible! How do you explain rust from using the wrong screws not showing up until I used Restore A Deck which you gave such a great review? Now I’m stuck with TWP semi transparent stain I can no longer use and will have to paint deck dark brown as trying to replace every screw in deck would be almost impossible and may damage boards.
Not a RAD cleaner issue but a screw issue. RAD prep products are used on many 1000s of decks per year without issues. You are blaming the wrong thing. Prep products do not cause rust. Metal rusts and your screws coating did not protect properly and failed.
BTW, to remove rust stains form screws a wood brightener would work.
I really appreciate your answer but had I not cleaned the deck I would have no black marks I believe I read they would continue to bleed through even if I brightened again? If I did same deal with letting entire deck dry for 48 hours and then use dark brown solid stain and that will fix ?
No, the cleaner products do not damage screw coatings that are properly manufactured. There is an issue with your screw batch.
You are blaming the wrong thing.
FYI, read the reviews for the screws on HD in the 1-star. A lot of issues with breaking or coating coming off within a year. Once this happens, they will rust. Bad batches have happened and you have one.
Thank you. None of this made sense to me until the OPW online store that sells TWP explained that during the cleaning process the friction from using a pressure washer or deck brush or sanding could strip the coating off the nail heads that were a bad batch or the wrong material and then they would subsequently rust. So I was correct in my assumption that the rusting was associated with the cleaning process – I used a deck brush – but I was incorrect in my assumption in was the cleaner that was the culprit. Just wanted to pass this on to your readers because it helped me to understand more. I appreciate your responses and the info on this site.
Wouldn’t the water rinsing the brightening agent just bleed out the rust again?
Hard to say if it will or will not come back.
I have a large deck that was stained with Sherwin Williams solid deck stain. It is starting to peel, and I would like to remove the solid stain and re-stain. Does the deck stain/paint remover take most of the solid stain off? Also, I have 1 by cedar wrap, and railing support as well. Would it be good to pressure wash and seal for the lasting raw cedar look?
Thanks
A stripper will not remove a solid color deck stain fully. You can strip off as much as possible and then sand the rest off. Use one of these stain brands after: https://www.deckstainhelp.com/the-5-best-deck-stain-reviews-and-ratings/
HI!
I have black rust spot from nails on my redwood fence- the redwood is untreated (we live in So Cal and have very good weather). The fence is beautiful other than the eye sores: black streaks around all the nails (just like your pictures show). Is there a way I can spot treat to remove the stains, without having to then stain the entire fence?
I have tries TSP (made the TSP, bleach and water mix, as well as the TSP water mix) , hydrogen peroxide solution, dawn soap (that cleaned the fence but did nothing to the black marks), oxalic acid. But all those change the color of the wood, significantly.
I’d love some feedback, guidance and help.
We love the color of the fence and do not want to change it at all by staining it.
Thanks in advance
Wood Brighteners will remove most rust spots but they will come back as soon as it rains. Applying a stain or sealer over it after will not prevent it from happening again. The only way to fix is to replace the nails and use properly treated nails or screws.
Thank you so much for the reply. Can I use the Wood Brightener to spot clean the rust spots?
Or would that change the color of the wood? In those spots
I am attaching pictures
Thank you in advance, if any of your products would work I would be thrilled
You cannot spot apply a brightener, all wood will need to be coated evenly.
Hello, first I’d like to thank you for this site. The best collection of information I’ve found. So I used pressure treated pine with bronze coated screws for a deck I built last summer. Most of the boards have cupped, so my plan was to flip them over, clean with oxiclean, brighten with oxalic acid and seal with Seal-Once clear. I tried this on a couple of boards, and it worked well, except after using oxalic acid to brighten the test boards, I got these black spots around the screw holes (screws had been removed). Any ideas of what caused them and how to get rid of them? Thanks again.
It is rust. The screws have gone bad or the coating has failed. Brighteners typically will remove rust spots in the wood.
Why are my nails rusting and bleeding out black stains on our brand new pressure treated deck and what should I do to fix this before staining it so they won’t show through?
Bad nails or the wrong ones were used. You cannot fix this issue permanently outside of replacing all the nails and using proper galvanized nails or stainless steel screws. Once that is done, you can use a wood cleaner and a wood brighener to remove the black prior to staining.
My treated wood was built in 1991 and the old galvanized screws have the black rust stains. The deck is stained with a solid color deck stain. I would like to seal the rust stains and restrain with a solid color stain. I used the rust oleum rust sealer but it failed. Any suggestions beside Deck Brightener
You cannot stop rust stains from your screws with a sealer and you also cannot seal first and then apply a solid stain over a sealer. The sealer will repel the stain and it will peel. Your best option is to replace all the bad screws and then solid stain all after prep.
I need to re-stain our textured no slip deck. Do I have to remove all the old paint before I re-texture it? And I’m getting conflicting reports on which textured stain is the most durable for both snow and sun extremes.
You will have to remove it all first. Once that is done, try the Gulf Synthetics coating.
How???? I’ve already power washed it 2x and sanded 🤦🏼♀️🤦🏼♀️🥵
Power sanding to remove all. https://www.deckstainhelp.com/why-sanding-a-deck-can-be-an-issue/
Will a good water seal like Thompson’s prevent the rust from oozing out again?
No, it is not possible to stop it.