What did I do wrong?

[Earl Johnson 14]

Cleaned a deck today with sodium hydroxide. It had alot of mildew. X-jeted it on and washed it off, then used oxalic acid. when the deck started to dry, it had alot of white placesall over it like chalky residue. I neutralized it 2 times and rinsed good and it still came back when it started to dry. Could it be the SH. I did a deck a couple of days ago and it came out great. Did it the same way. Only difference is a different batch of SH. I have to go back tommorow and fix this fast!..... Help sombody!! Thanks Earl

[Earl Johnson 14]

I meant to say Sodium Hypoclorite

[Dale 16]

Earl,

How much pressure did you use?...sometimes if you look at the right angle, fuzzies look kinda silvery-white. Did you get right down there and look at it? Sodium Hypo shouldn't have a residue.

I'm just guessing, Dale

[ParadiseProWash 14]

When I first started out I ran into this problem. I was using Olympic deck cleaner and it had a white look to it. This was just a charactistic of the cleaner I think. Its kind of like using bleach. All I can tell you is to rinse rinse rinse and then rinse some more. The only other option I could give you is to reclean the deck with something like the EFC-38 which is a percarb cleaner it should fix it right up and then neutrilize it.:D

[Paul B. 523]

Sodium Hypochlorite comes from salt and then turns back into salt as it breaks down. There is a large debate about using it on wood as it CAN break down the wood structure. It has a bleaching or whitening effect. You could be seeing that. (Personally, I avoid using it on decks.)

A photo would come in handy in this type of situation.

What protection or sealer / stain is on the wood now? Is it in good shape?

Sight unseen, I would agree with Morgan on rinsing, rinsing and if the problem persists, try a light mix of EFC-38 precarb cleaner apply and rinse with low pressure (no more than 500-800psi).

Another issue with Sodium Hypochlorite is that it only has a shelf life of about 90 days from time of mfg. (give or take). It's a shame that most containers are not date stamped. I purchase my supply from a local pool supply store because he buys it directly from the local manufacturer and can provide expiration dates for me.

I date all our supply.

[Earl Johnson 14]

The deck has never been sealed and is in good condition other than the mildew. I did use somewhat high pressure but stayed off the deck about 6-8 inches. There are very few fuzzies. T he white won't rub off and disapears when I wet it. When it starts drying is when you can see it. It's worse around knots and vertical surfaces and bad on the lattice. I think I rinsed good ( with pressure and water hose) and then neutralized 3 TIMES. Now that I think of it, seems like it is mainly on the rougher wood like the lattice and spendles.

Paul, Shouldn't the acid neutralize the sodium? I thought it was the sodium that I was seeing but it sure don't want to come off. Some did, but alot didn't. I don't have EFC-38. Is there anything else I could try? Thanks Earl

[Paul B. 523]

I have a couple of estimates to do so this is brief (I'm heading out the door). Will follow up this afternoon.

Salt and Efflorescence behaves in that fashion on other substrates. When you wet it, it disappears but as it dries, it reappears. Warm water will help dissolve it quickest but should be careful with it on wood. Again it could also be a bleached effect that you are seeing. But Sodium Hypochlorite (12-14% content) has a pH between 11-13.5 at 20 degrees C.

Yes, acid based cleaner should neutralize the salt.

I use acid based cleaner to remove efflorescence from bricks.

Local Sears hardware has Wolman deck cleaner brightener that's a percarb based crystal (off the top of my head I don't recall the comparative content to EFC-38 - EFC-38 is overall a much better product).

[ParadiseProWash 14]

I agree with Paul on his last answer if you just have to do it now get the Wolmans Deck Brite and in the future stay away from the Sodium Hypo... on wood. When working on a grayed deck with nothing ever applied a percarb or Oxcilic based cleaner is always your best route.

[Earl Johnson 14]

Precarb or Oxalic clean mildew? Sears here don't stock Wolmans deck cleaner so I guess I'll try the acid and pressure rinse again and see what happens. I still don't understand why the deck before this one turned out fine. The only difference is I used a different container of SH :confused: I'll be back with the results. Earl

[Paul B. 523]

As I stated, SH is date sensetive - 90 days max. avg. from date of mfg. and strength decreases daily, even unopened. (SH works better in sun than in shade). I purchased 6 cases from a pool supply house last year and used 3 on my pool over a 2 day period w/o results. I had it tested and it was flat. Needless to say I dont buy from anyone alse except people that turn it over quickly - I have one supplier.

I would also suggest getting a supply of EFC-38 from TheGrimeScene as it's not only a good cleaner for decks but also can be mixed as a stripper and also mixed for use on house cleaning. If I ever saw a product that was flexible, this would be it. All the directions are on the tub so the mixing is easy even before your first cup of coffee in the morning.

Like I said try some warm to hot water on a few spots to see how it reacts before spending a bunch of time on the whole deck. Test small areas then go full scale.

Good Luck!

[Littlefield 65]

Keep in mind you can over "neutralize" too. You are neutralizing the first time, then you are just making the surface more and more acidic. You can have acid crystals form a white film, too.

Just a thought, be gentle with wood, its not like plastic, it reacts with each step....

Hope this helps

[Earl Johnson 14]

This deck was in full sun unlike the one before so that may have played a part. I went and looked at it this afternoon and didn't look as bad as it did yesterday. It still looks like it has a white film in some places. It rained last night some, so maybe that helped although I rinsed alot.

Littlefield, I put oxalic on 3 times on some spots ( about 30oz./5gal) and each time it seemed to help until the last time, it didn't seem to do much. Did I over do it? Should I rinse again, or what to prepare it for sealing.

[Paul B. 523]

As I said, try warm to hot water in a small area to see what effect this may have. Additional rinsing should help if it's salt that you are seeing. May want to let it sit for a few days and check other areas if it's bleaching then these should darken with time.

Attached is a photo of an anodized aluminum pole that was left in a swimming pool for a day (maybe 2). You can see the salt build-up from the chlorine (I tasted it).

[Johny 14]

Chalky residue,either you didn't neutralize properly and you are seeing white bleach residue,or you had your oxalic too strong or possibly let it dry,hot water takes care of that,8oz per gal is all you need

Johny

[Johny 14]

Also you stated ,residue when it started to dry,have you looked at it when it's completely dry??

Johny

[Earl Johnson 14]

It don't look like the pole. It's not crystiized, more powdered looking although it don't rub off. I'll try warm water tomorrow.

Johny, It could have dried in some places, so that may be part of the problem, but if anything, I mixed the acid weak. When it is completly dry it seems to look better than right after it started to dry. So what does that mean?

I looked at it again today and looks better, but still has the white look on knots and lattice. Tommorow I'll do something even if it means P/Wing the whole deck. I'll post the turn-out. Thanks again everybody for all the input. Earl

[Paul B. 523]

Earl,

The pole photo was a dramatization of chlorine turning to salt.

There is one more thing that you can do. If that's an acid residue, you can neutralize or buffer its effect with sodium bicarbonate (plain old baking soda - should have remembered from my old chemistry lessons). I always keep several boxes on each trailer and truck as we work with a lot of acids. Along with rinsing, baking soda will be your fastest neutralizer for acids - good for indigestion of the wood and your stomach.

As someone else mentioned, percarbonate cleaners are also slightly acidic and may help to neutralize your surface if your PH is above 7. As an added note, lot of folks carry vinegar, as it is an acid and will neutralize the effects of alkalyn based strippers.

Another way to tell what the white areas are would be to wet the area and place a strip of litmus paper on the damp surface. This should give you a peek at the woods pH. Litmus paper (pH strips) can be had at your local pool supply houses - some K-Mart and Meijer stores that carry pool supplies may also have it on their shelves.

[Johny 14]

That sounds like you let either bleach dry before neutralized or acid could have dried.I dont think its a big deal,if you reclean the floor it should come off.Bleach residue won't show through the finish,acid residue will and has to be cleaned.If its acid hot water will do the job.If you don't have a hot pw,you can rent one

Johny

[Earl Johnson 14]

today. Only way I could apply it was with a pump up sprayer. Made very little difference if any at all. I took a wide wire brush and brushed the spindles (where most of the residue was) and that took alot of it off. The worst of the residue was on the virtical surfaces. It started raining so I didn't try anything else. I'll see what the rain does to it then I'll try vinagar. I think the problem is from the SH, but I don't understand why the deck before this one turned out so good. Maybe this batch was more potent.

Thanks for the baking soda and vinegar info.

I'll be back after the rain........ Earl

[Earl Johnson 14]

got my meter and sample kit and HD-80 today. Can't wait to try it all. Thank you for the quick response and your help. Earl

[Dale 16]

Earl,

Can you get a pic of what you're talking about?, it would really help everyone see...what could it be??? wood is basically wood, if the finish came off whats left should either rinse off or de-fuzz?

Don't want to freak you out, but a wire brush may not be the best idea,sometimes the bristles break off and can rust...if you sweep it off or use a blower before you stain/seal it should be O.K.

Dale

[Earl Johnson 14]

I don't have a way to post pictures (wish I did). I was careful with the wire brush and it didn't take much pressure to get it off, but it won't sweep off. It looks like I didn't rinse the SH at all, but I rinsed and rinsed and rinsed some more. I'm not freaking (not yet anyway...lol) Earl

[Johny 14]

Now it definetly sounds like you let oxalic dry.Thats it's residue that is showing and will show throught the finish when it dries.But don't stress over it,its just a deck.If you show up too many times trying to fix a problem ,the owner will freak out,thinking its bad.Hot water with pump up wont do it.I remember reading a post long time ago on this issue,and man rented a hot powerwasher and it all come off easy,it was on powerwashnetwork.com,do a search and you will find it

Johny

[Paul B. 523]

The reasons Johny mentioned were why I recommended litmus paper. It should help take the guessing out of your game and make choosing the right solution a lot faster if you know what pH area you are dealing in.

I also remember the post - and if I remember correctly, those crystals were caused by the oxalic not being fully rinsed and appeared on a sealed deck. It was successfully removed with a light hot water washing.

[Earl Johnson 14]

I'm on my way to get the paper and test!!

[Earl Johnson 14]

Got the ph paper, tested, and the ph was on the low side so I'm assuming the oxalic didn't rinse off. I did a light HD-80 wash (1st time using it) and it turned out great!!! No more white powdery film. IT LOOKS REALLY GOOD!!! Now the question is, How much darn rinsing has to be done to get that dredful stuff off? (oxalic) I no it must be rinsed very very good and then rinse again and that is what I did, I thought. The oxalic I have is Technical Grade Dehydrate Crystals 99.6%. Is this what anybody else uses?

I really appreicate all the help from you guys. I was starting to sweat a little on this one. This is a high exposure area and it has to be right, although they all have to be right. So thanks again for taking the time to help a newbe out

Happy as a hog in slop, Earl