Using a surface cleaner on wood

Some contractors use surface cleaners on wood deck floors. If the wood is completely petrified, that probably works OK.

On the other hand, there are a few great reasons to never use that kind of tool on a deck. First of all, surface cleaners do not even spin without around 2000 PSI moving through them, which is way too much pressure for most types of wood. Ipe might be an exception, but setting exceptions can leave room for a mistake.

Washing wood with low pressure and strong cleaners is the original "soft wash" - something common in the wood world for twenty years. Using a surface cleaner at 3500 PSI is not my definition of "soft wash".

Secondly, for somewhere between 20% and 80% of the circular path a surface cleaner makes, you are working against the grain. Your old shop teacher always told you to sand with the grain, and I support that. When you use that kind of pressure and work against the grain, you will very likely hollow out the soft wood between the grain lines. This ends up looking like "raised grain" but they ought to call it "lowered pulp".

Anyway, That is one of the basics about working on decks. If you are tempted to go at that large deck with a surface cleaner, please think twice.

The only reason for using a tool like this (meant for concrete) on wood is speed. I can match the speed and get better results by using low pressure and quality cleaners or strippers.

Like everybody else, I learned a lot by making mistakes. I am trying to help you avoid this easy mistake. I know I will see a few replies telling me that they do this all the time without any problems. I would argue that the problems are there, just not looking to close at them.

Let me know what you think.

Great info.

Can you explain the wood cleaners, there application and purpose

I have seen circular scaring in the wood from surface cleaners as well.

Cleaners

Wood is a pretty complex topic to get done in one post, but here are the basics. To start, clean wood with a caustic cleaner (alkaline, base, pH higher than 7). The stronger the cleaner, the less aggressive you have to be with pressure. If you are stripping an oil sealer, you simply use a stronger dose of your everyday caustic wood cleaner. Instead of mixing your concentrate with 5 gallons of water, you can just just mix it with three. If what you have is a strong deck stripper, mix according to directions for stripping but add extra water when mixing it for simple cleaning.

One important thing to understand - don't use a driveway cleaner or some degreaser. Wood cleaners are made with low-sudsing surfactants because too much soap makes you spend an extra hour rinsing. It's easy to find something made just for wood (rather than a general-purpose caustic cleaner).

Everybody who sells cleaners makes something for wood. Everybody has their own preference. I like what I make, which ought to be obvious.

Two more points about cleaners. One, the last person in line for approving a cleaner for sale at a big box store is an attorney. We live in a time when Mickey D's gets sued because the coffee was hot. No one is going to sell a homeowner a stripper strong enough to burn the customer. On the other hand, wood guys use stuff that would make General Patton nervous.

The other point is that wood cleaning is a two step process. The second step is brightening. This is an acid treatment (no soap involved). Some guys use straight oxalic acid. I prefer a blend of acids (citric, oxalic, and phosphoric) for the results.

As far as application, I like the dwell method. Apply the cleaner over the surface and let it sit. If you are stripping an old sealer off, just watch the surface. As soon as the wood darkens, that means it is time to rinse it off, usually with 300 to 800 PSI. The wood darkens because it is wet, which means the cleaner has penetrated through the old sealer and hit the wood.

Hope this helps.

Pete which one is the everyday caustic wood cleaner are you referring to?, you have quite a few wood cleaners on your website.



Interesting tip on the brightening agents blend, never heard that one.



Whats the plus of a acid blend vs staright Ox? (In the back of my mind I am thinking about the positives of a multi viscosity oil over a straight body oil)

It's obvious that I have a lot to learn about cleaning and restoring wood surfaces! I have a new goal for this year: To properly learn wood cleaning and to get set up with the right equipment and cleaning "agents" to do a great job. I wish the ATL round table was a little later in year because I have a conflict with that date (as that RT could be useful for those wanting to learn about this subject). Hopefully, there will be another one soon near Florida! Thanks Pete.

Good Stuff Pete

810f250 said:

Pete which one is the everyday caustic wood cleaner are you referring to?, you have quite a few wood cleaners on your website.


Interesting tip on the brightening agents blend, never heard that one.

Whats the plus of a acid blend vs staright Ox? (In the back of my mind I am thinking about the positives of a multi viscosity oil over a straight body oil)

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I like Rip It, which is a powder and the strongest stuff we offer. An extremely strong stripper that, watered down, makes a great cleaner. Also use it for driveways.

The blend of acids in a good brightener accomplishes two things. First, it does a better job on certain woods, like redwood and cedar. I think the blend is about equalt to straight Ox on PT. Secondly, it gives you the benefits of using Ox without exposing you to as much Ox as a straight chem does.

Ox is not proven to be a health hazard. It occurs in nature in plants and some vegetables. All of us have been exposed to Ox, whether we are wood guys or just fourth-graders. Oxalic is systemic, which means that once it is in your system it is there forever. Here is an article that sums up my thoughts.

So we all have it in our system. A hundred years from now they will tell us it causes problems in seniors or something. In the meantime, I do my best to minimize my exposure. I have used straight Ox in the past, but switched to a blend about ten years ago. Everybody has to think for themselves about this, because you can't do a great job on wood without using some oxalic.

Man, these are some great questions. I love being a wood guy.

Thanks Pete, great info,

I have inhaled ox acid mist before, not nice at all.


How would you recommend we apply the cleaner and brightener?

Would the delvan pumps hold up to spraying either of the chems?

What about overspray on plant and grass with each of the chems?

Wait a minute...

I just re-read that article, and it talks about the body getting rid of oxalic in most cases. The physician I talked to about this years ago explained that oxalic is systemic. Seems like conflicting points, but the important thing is to be aware - and not make it a habit to drink the stuff with my PB&J at lunch. I know I have already eaten enough Ready Seal. Tastes pretty good.

810f250 said:

Thanks Pete, great info,

I have inhaled ox acid mist before, not nice at all.


How would you recommend we apply the cleaner and brightener?

Would the delvan pumps hold up to spraying either of the chems?

What about overspray on plant and grass with each of the chems?

Click to expand...

Kind of takes your breath away, doesn't it? I spray the chems onto the wood, either with a powered sprayer or a pump up. I am not as intimate with the Delevans as Bob, but I believe they will hold up OK as long as you rinse the pump system thoroughly after use. You should check with Bob on that.

Overspray should not be a problem if you approach the job right. The caustic will attack aluminum (screens, doors, sills, etc) and the brightener, which is an acid, will etch the glass. These reactions take a lot of time to occur (hours or days, not minutes). Simply rinse EVERYTHING carefully when you are done with the job and you will not have any issues.

Pete,

I have been using Rip It as recommended, 6oz. to 1 gal H2O, actually a little less than on label as I was afraid of it being too strong. I applied it with a pump sprayer, and did several applications with low pressure powerwash in between (2450psi machine with white tip, approx. 6-8in from surface). I did a recent deck Press Treated Wood, with a lot of UV damage and an unknown time since it was last cleaned, stripped or sealed. I got a lot of fuzzing especially on hand rails and spindles? I know this is sometimes unavoidable, but any suggestions on what to do with next deck to limit the fuzzing. Also had a lot of green spots left from mold / algae growth, should this be treated with a separate cleaner? Have to do another deck in same complex, which appers to be same condition possibly worse, very dry and high UV damage.

Thanks
Matt

Also forgot I used wood brightner from SunBrite after the Ripit, but still had a lot of bad fuzzing. Don't know if chem was too strong or if too high pressure? Any suggestions would be greatly appreciated.

Thanks for the questions. First off, sodium hydroxide products actually break down the lignin in the wood. The result is the "fuzzies" you seem to have experienced. The easy slogan that tells you what happened is "If it is on too long or too strong, you will fuzz the wood". Since Rip-It is so strong (made for stubborn finishes) it may only have to be on the surface as little as 30 seconds for easy finishes like RS.

Your technique was fine. The 6" - 8" distance is great. Did you use over-size tips to reduce the pressure? If not, what you really see is called "furring" (which is more severe than fuzzing). When you melt the lignin and then go with higher pressure, the results can look pretty rough. Pressure should be dropped as low as 300 - 800 PSI, which I am guessing means a 5.0 or 5.5 nozzle orifice for your pressure washer. Call me if you don't understand the nozzle size thing. 770-277-9924

Using the Britener stops the chemical reaction of melting the lignin, so that was a good thing to do on general principles.

How do you know when the stripper has done the job and you can start washing the wood? Wood turns dark when it is wet, so apply the stripper and then watch the deck floor itself. As soon as it starts to darken (somewhere between 30 seconds and about 10 minutes - depending on what you are stripping) you should immediately start the washing process. That technique will minimize any fuzzies in your future.

I always enjoyed working on wood in beautiful back yards! Have fun!

Great Info

Pete Marentay said:

Some contractors use surface cleaners on wood deck floors. If the wood is completely petrified, that probably works OK.

On the other hand, there are a few great reasons to never use that kind of tool on a deck. First of all, surface cleaners do not even spin without around 2000 PSI moving through them, which is way too much pressure for most types of wood. Ipe might be an exception, but setting exceptions can leave room for a mistake.

Washing wood with low pressure and strong cleaners is the original "soft wash" - something common in the wood world for twenty years. Using a surface cleaner at 3500 PSI is not my definition of "soft wash".

Secondly, for somewhere between 20% and 80% of the circular path a surface cleaner makes, you are working against the grain. Your old shop teacher always told you to sand with the grain, and I support that. When you use that kind of pressure and work against the grain, you will very likely hollow out the soft wood between the grain lines. This ends up looking like "raised grain" but they ought to call it "lowered pulp".

Anyway, That is one of the basics about working on decks. If you are tempted to go at that large deck with a surface cleaner, please think twice.

The only reason for using a tool like this (meant for concrete) on wood is speed. I can match the speed and get better results by using low pressure and quality cleaners or strippers.

Like everybody else, I learned a lot by making mistakes. I am trying to help you avoid this easy mistake. I know I will see a few replies telling me that they do this all the time without any problems. I would argue that the problems are there, just not looking to close at them.

Let me know what you think.

Click to expand...