Remove Black Mold and Mildew Stains | Open Wood Pores | Prepare the Deck for Deck Stain | Nuetralize Tannic Acid | Remove Mill Glaze
Information on Deck Cleaning
If you have a wood deck, you know how much your deck can affect the overall look of your property. An old weathered deck can lower resale value and detract from the enjoyment you get from your home. When a deck is beautiful and well maintained it is a joy to be near, makes the whole property feel nice and keeps the wood from needing to be replaced. If you apply the right products you can maintain your deck indefinitely. With the wrong products deck maintenance becomes laborious, tedious and it just doesn’t get done, ending up in costly deck replacement.
Why do Decks need to be Cleaned?
If you want your deck to look its best and be truly protected it can be helpful to consider this: A deck sits outside, flat, horizontally exposed to the full elements all year. Additionally, it typically only gets one or two coats of deck stain and seldom gets washed other than rain, which tends to be acidic. Compare this to a wood floor which gets no weather, often has 3-4 coats of finish and is washed regularly and it’s easy to see why a deck weathers so quickly. If you clean the deck twice a year, in the spring and fall you will prolong its life and keep contaminants from embedding themselves too deeply. The most important reason for cleaning a deck is that if you stain over on improperly prepared deck, you can make this worse. Much worse. So bad in fact you'll wish you never stained your deck to begin with. If you properly clean you deck before staining your deck stain will last longer, penetrate deeper, fully coat the wood fibers, stain more evenly, be free of contaminants and have a the correct pH.
My Deck is Brand New. Do I Still Have to Wash It?
Yes. It will open up the wood pores; remove contaminants acquired during transport and shipping and help to provide a longer lasting deck stain base. If it’s been outside more than 2 weeks definitely wash it. Any wood that is outside more than two weeks should be washed before coating. Mold, Mildew and Algae spores are abundant outside. If your wood has been outdoors exposed to the weather it should be washed before you apply a deck stain over it. If you do not do this you could wind up sealing in fungi spores and giving them an atrium to grow in. This could cause them to spread. It is very, very hard to fix this. Avoid it at all costs. The wood turns black under the coating and then it needs to be fully stripped in order to fix it. Play it safe and wash all exterior wood before staining.
How Can I Clean My Deck Easily?
It is recommended that deck cleaning is done every spring and and fall to ensure that it is maintained in top condition and easy to clean without too much buildup. This doesn’t have to be a big process. It can be as simple as using some Citrus Solvent Cleaner in water and a giving quick scrubbing to the deck floor. However, to prep the deck for staining or to clean heavily weathered decks a few things should be considered.
What is the Best Deck Cleaner?
Lime Clean is the only deck cleaner that uses the mineral Lime as its base. It’s strong enough for the brutal deck environment while still being biodegradable, naturally derived, low odor and safe to use.
Lime Clean is a deck cleaner that gets brushed onto wet wood and left for 20 minutes and then scrubbed or pressure washed off. It doesn’t require a contractor to do it. The white color allows you to see the product cleaning the deck and lets you know that it has been rinsed off. It gets rinsed into the ground where it neutralizes acidic soil and becomes calcium carbonate or chalk. In fact, one of the greatest qualities of the Lime Clean is the way that it neutralizes tannic acid. This has shown to be a vital part of deck prep since tannins can cause coatings to fail especially on cedar, ipe’, mahogany and other exotic wood types.
If wood is black or grey, the Lime Clean will loosen it up so that a scrubbing can easily remove most or all of the dead, weathered wood. This will reveal fresh strong wood beneath, without sanding. It also will remove the mill glaze that is created when the saw blade heats against the wood and seals the pores. By removing this mill glaze the wood can accept stain deeper, more evenly which helps it last a great deal longer.
Lime Clean leaves a thin protective layer after it is rinsed. Leave this in place while the deck dries, pH will naturally balance.Coat as soon as dry with Rainforest Sealer or Mountain XT.
What are the Health and Environmental Issues of Lime for Deck Cleaning?
Unlike bleach, ground water pollution is not a concern with lime. Lime has been used by farmers to balance pH in soil for centuries. Drinking water is treated with it in specified ways. Dentists use calcium hydroxide for temporary dental fillings. Lime is just a good all around deck cleaner. That said, it is a strong cleaner, like bleach, so you don’t want to get it all over you, breathe it in your lungs or in your eyes. If I leave it on my hands for half a day or so when I’m cleaning a deck, I’ll notice the next day that my skin is a bit dry. Look at a stone masons hands and you’ll see what daily use of lime can do to your skin. So wash the deck with it, not your skin or eyes. Decks require a strong cleaner and of all the options available, lime appears to be the safest, most effective way to get the job done right.
What are the Health and Environmental Issues of Bleach for Deck Cleaning?
Bleach is the easiest, cheapest, most common way to clean a deck BUT (In my opinion) it’s also one of the worst for the environment. Bleach and Tri Sodium Phosphate or TSP is more effective at killing black mold and mildew but not only introduces bleach into the environment but also puts phosphates into the ground which is considered bad for water. Sodium Hypochlorite, which is used to make bleach is toxic to aquatic life. Since it is most always rinsed into the ground it is highly likely to affect water systems.
Interestingly, there used to be more information regarding bleach, toxicity and acid rain but I suspect the 72 $bn industry has done a very good job of changing public information on the Internet. I’ve worked with scientists who work with bleach for a living and even they acknowledged to me its toxicity and one said that as it evaporates into the atmosphere it can contribute to acid rain. I don’t know if that is true or not but if you read Clorox’s site information, bleach would seem like the best thing since sliced bread. I’m not inclined to believe it. If nothing else I don’t want my worms getting bleach on them since I do organic gardening. Here is an excerpt on bleach from the UK that seems pretty reasonable.
“Organochlorines and Dioxins
But the real problem with bleach is that it is produced as part of the darker organochlorine group of chemicals from which dioxins are produced. Organochlorines are harmful to aquatic life, polluting to water and are hard to get rid of. Dioxins are highly dangerous, both to humans and the environment. Because bleaches are manufactured as part of this sector of chemicals, if we buy them, we are helping to support the industry which produces these kinds of pollutants.” Pollution Issues UK
What are the Health and Environmental Issues of Oxalic Acid for Deck Cleaning?
Oxalic Acid is the next most common chemical used for deck cleaning after bleach. I’ve used it extensively and it works pretty good. The only negative thing I noticed is that I did get all over my skin and I tended to breathe in a good deal of it since I was spraying it on, sometimes into the wind. The EPA makes this statement on it but I would add that since it is always diluted with water these severe health effects are not what I’ve experienced.
“Oxalic acid is corrosive to the eyes and skin, and has been placed in Toxicity Category I (indicating the highest degree of toxicity) for acute eye and skin irritation effects. It also is highly irritating and damaging to the respiratory system if inhaled. Acute exposure also causes stomach irritation, lowered calcium levels, effects to the nervous system and kidney damage in humans. “ EPA it goes on...Ecological Effects EPA did not require or evaluate ecological effects data for oxalic acid because the pesticide is only used indoors and exposure to wildlife is not expected to occur. EPA
To the EPA’s credit they are requiring more studies for environmental impacts on wildlife such as “birds, freshwater fish and invertebrate species.” But clearly since it is used to clean decks perhaps these studies would have been done by now.
The bottom line on Oxalic Acid is, I would use it over bleach if I couldn’t use Lime Clean. It is rapidly biodegradable in a day and as long as you keep it off of you it seems ok. Perhaps the best place for this cleaner is upper decks that overhang rooftops and areas that require a clear transparent cleaner.
[Who does the study? We should collectively disregard all health and environmental studies paid for by the industry they pertain to. Unfortunately, these are very common studies. Whenever I see smoothing like, “The EPA relied on available scientific studies.” it seems clear that any multinational corporation could pay for that available scientific study the EPA uses. It’s not like corporations don’t pay professors from Harvard and other fine institutions to do studies now. But this is grounds for another article. ]
Does Oxygen Bleach Work for Preparing Decks for Staining?
Sodium percarbonate, sodium carbonate peroxyhydrate, and sodium carbonate peroxide all could fall under the name Oxygen Bleach.
First of all, I can't speak for all products. All I can do in this instance is give my experience. I find it’s a good cleaner that I like, but I wouldn’t use it to clean a deck in Asheville or any high mold area.
For years there were hopes for this cleaner to work on decks. It has been shown to kill mold in a lab. So we tested it. Once applied you can see amazing results, the wood immediately turned a fresh color, which everyone loves. Coating some areas with deck stain and leaving some raw, the samples were monitored in an outdoor, high mold environment in the mountains of Asheville, NC at two seperate sites of 1000 and 2200 ft elevations. The mold always came back, sometimes within a couple weeks, even with highly concentrated solutions. Does this prove it doesn't work. No. It just shows me I wouldn't use it or sell it for deck cleaning. Especially since many people wait a couple weeks after washing the deck before they stain it.
All of the tests that I have seen show me that oxygen bleach is not strong enough to penetrate deeply into the wood and kill the fungi in high black mold area. Perhaps, somebody has come up with a way of making it work but I wouldn’t use it until I saw proof. The last thing I want to do is stain over black mold spores. I see cleaners on the market that use OB and then an Oxalic Acid which makes sense since the Oxalic Acid does a good job of killing fungi and the OB bleaches the wood. I always use mid to deep toned deck stain so I don't need to lighten the color of a deck in 99% of instances.
OB may work in a petri dish or on indoor mildew but the deck world is very different than the indoor lab world. Oxygen bleach seems fine in the few instances that you need to to lighten the color of your deck. It is good for a mild house wash. The health and environmental profile of Oxygen Bleach is pretty good as well, similar to lime. It’s too bad it’s not stronger.