# Injecting Sodium Hydroxide



## Hines Painting

Does anyone know if downstreaming sodium hydroxide will work for stripping stain? I'm assuming it will but I've never tried it. 

At a chemical supply house I can get 25% hydroxide for about 6 dollars a gallon. My thought was to mix it with water at a 1:1 ratio and then downstream it 12:1 so that I end up with about 1% on the siding.

Sound reasonable, or is that too weak to strip anything? I don't need it too strong, but stronger than Gemini Safestrip.

Followed up by a downstreamed oxalic acid but I'm still looking for mix numbers on that.


----------



## Rapid HotClean

Have never done that on a vertical surface, so don't know.


----------



## Hines Painting

I have a general plan for it, but I need to figure out what rate my injector draws at first.


----------



## Stretch67

Well if you figure it out make sure you post up! I'm looking at doing the same thing over the next couple days.


----------



## straight_lines

Oil or acrylic stain? I am not sure your ratios will be strong enough but you can adjust that as needed. 

If its acrylic stain it will be much harder to strip.


----------



## Hines Painting

I figured it out! Furred the crap out of the wood, but from what I understand cedar is prone to that anyways. 

When I started my mix was way too strong. (I'm not sure if I should use the term "Hot". I know sodium hydroxide heats up when mixed with water, but I bought it premixed so it was rather cool, but is the correct term still "hot"?)

I started with 50% sodium Hydroxide (NaOH), premixed by the chemical supply where I purchased it. My injector works at a 10:1 ratio, so the amount hitting the wall was about 4.55%. I also called Bob at pressuretek and asked what he thought about mixing Elemonator with sodium hydroxide. He said he had never tested it, but he didn't see why it would be a problem. I had tried just straight NaOH the day before and the Elemonator (1 oz per gallon) definitely made a huge improvement. Just make sure you premix it with a little water first. If you dump it straight in it gums up.









As you can see from the second half of the picture it stripped the paint off of the deck at 4.55%. I suspect the elemonator aided in that, because the side of the garage with the man door was done without elemonator and no paint came off the door. The age and the horizontal surface could have played a factor as well.

So for today I mixed 2 gallons of 50% NaOH + 1 gallon of water + 3oz Elemonator for a 3% solution of NaOH. It didn't fur as bad, but still more than I would like. I finished the job at this ratio, so I didn't have time (or wall space) to try a further reduction. My next step was going to be 1:1 for the 50% + h2o + elemonator; for a dillution of around 2.3%. 

At 3% it cleaned the surface of the redwood deck (not pictured) in about 30 seconds and didn't fur at all. So 3% might be correct for redwood. Although a lighter mix might have still done it just fine. 

For the brightener I used Storm System Brightener/Neutralizer applied by downstream. It says to dilute it at 8:1 but I couldn't tell any difference at 10:1; the back wall (lower in the picture) looks pretty bright to me.


----------



## stelzerpaintinginc.

Hines Painting said:


> I figured it out! Furred the crap out of the wood, but from what I understand cedar is prone to that anyways.
> 
> When I started my mix was way too strong. (I'm not sure if I should use the term "Hot". I know sodium hydroxide heats up when mixed with water, but I bought it premixed so it was rather cool, but is the correct term still "hot"?)
> 
> I started with 50% sodium Hydroxide (NaOH), premixed by the chemical supply where I purchased it. My injector works at a 10:1 ratio, so the amount hitting the wall was about 4.55%. I also called Bob at pressuretek and asked what he thought about mixing Elemonator with sodium hydroxide. He said he had never tested it, but he didn't see why it would be a problem. I had tried just straight NaOH the day before and the Elemonator (1 oz per gallon) definitely made a huge improvement. Just make sure you premix it with a little water first. If you dump it straight in it gums up.
> 
> View attachment 25898
> 
> 
> As you can see from the second half of the picture it stripped the paint off of the deck at 4.55%. I suspect the elemonator aided in that, because the side of the garage with the man door was done without elemonator and no paint came off the door. The age and the horizontal surface could have played a factor as well.
> 
> So for today I mixed 2 gallons of 50% NaOH + 1 gallon of water + 3oz Elemonator for a 3% solution of NaOH. It didn't fur as bad, but still more than I would like. I finished the job at this ratio, so I didn't have time (or wall space) to try a further reduction. My next step was going to be 1:1 for the 50% + h2o + elemonator; for a dillution of around 2.3%.
> 
> At 3% it cleaned the surface of the redwood deck (not pictured) in about 30 seconds and didn't fur at all. So 3% might be correct for redwood. Although a lighter mix might have still done it just fine.
> 
> For the brightener I used Storm System Brightener/Neutralizer applied by downstream. It says to dilute it at 8:1 but I couldn't tell any difference at 10:1; the back wall (lower in the picture) looks pretty bright to me.



Great info. Looks like you got a good system that works. 


Stelzer Painting Inc.


----------



## Hines Painting

stelzerpaintinginc. said:


> Great info. Looks like you got a good system that works.



Ya, this is my second strip job of the year. The first one (deck) was done with pump sprayers and cabot's problem solver. And cost me about $650 in stripper (16 gal) and brightener (4 gal).

This one was $105 for NaOH (12 gal, 2 left) and $308 (12 Gal) for brightener. If I had planned better I could've got a powdered brightener for about $50, so the cost is definitely much better this way. Granted, I wouldn't have needed 110 gallons (10 [gal]x11[injection rate]) of stripper/brightener if I wasn't downstreaming, but I also saved at least a day in labor doing it this way, if not more.

If I was better at downstreaming I could have got away with a few less gallons of brightener as well. 

I think I'm going to give up stripping around painted surfaces (decks on painted houses) unless they understand they need to repaint everything around or unless I come up with a better way of masking, cause tape certainly doesn't hold up; not even duct tape.


----------



## Hines Painting

I should also clarify, this being my second strip job does not make me an expert and I wasn't trying to imply that. 

I just know that the last one did not go smoothly or easily and I am willing to take calculated risks, such as trying something that I can't find direct plans for but may backfire badly, or give me extreme chemical burns if I'm not careful.


----------



## Stretch67

Thats awesome!! I am doing almost the same thing right now. So to clarify, r u downstreaming the naoh full time? Or do u just downstream to get everything wet and the chemicals working on the surface, then remove the chemical injection from your pump, and pressure wash it off with plain water?

What is the procedure I guess I am asking? Can I get er set up, and then just get in the lift and start washing for 6-8 hours without going down to monkey with my pump?


----------



## Hines Painting

I dont remove the injection from the machine, I just switch tips. Or if i need to keep the soap tip on ill just stick the injector in a bucket of water. 

Steps were:
1. Shoot NaOH on surface.
2. Let dwell for a few minutes.
3. Rinse off.
4. Repeat above steps with Neutralizer (oxalic acid).

Bryce, if you can find it, try the safestrip. It would probably be sufficient for your goals.

Also, adding a tire valve to a pump sprayer allows you to pump it with a compressor. Thank Bill for that tip if you do it. 

When I did the deck I put 30 feet of line on my pump sprayer and used a lockīng air chuck and set my compressor to 40 psi so it kept an even pressure until i ran out of material.


----------



## Rapid HotClean

Good stuff Michael!


----------



## CRS

*Chemical cleaning*

I have extensive experience in exterior wood restoration. Many exterior stains "penetrating' type can easily be stripped with caustic soda (sodium hydroxide).

I have set up contractors using a blend of Sodium hydroxide / Sodium Percarbonate / Sodium Metasilicate which makes one of the most effective all around strippers/mold killers/cleaners. Oxalic Acid, or blends of Oxalic/Citric acid are effective neutalizers. Phosphoric is probably the best, yet handling is not near as safe and it is more expensive to use.

For film build exterior wood finishes, i.e. Sikkens/Timberflex, etc we are gelling the Sodium Hydroxide/ Percarbonate blend. This mix is brushed on and allowed to sit ... basically overnight. Highly effective inexpensive stripper.

Buy all your chemicals direct, in powder form. My last sodium hydroxide purchase was $.48 lb. Most ready made strippers containing this active have less than 1 lb. of Sodium Hydroxide.

Use a chemical sprayer. I have helped many set up their own and have experience in the design / parts, etc.

Feel free to contact me if you would like more info. [email protected]


----------



## DunriteNJ

I wouldnt run Sodium Hydrox through my DS for a few reasons

-probably wouldnt be strong enough to effectively do the job, even striaght

and more importantly i dont want any caustic going through my system

I would get a dedicated chem sprayer $100-$400 depending on what your looking for

even a pump up sprayer for decks works- much better 

Just my 2 cents


----------



## Hines Painting

DunriteNJ said:


> I wouldnt run Sodium Hydrox through my DS for a few reasons
> 
> -probably wouldnt be strong enough to effectively do the job, even striaght
> 
> and more importantly i dont want any caustic going through my system
> 
> I would get a dedicated chem sprayer $100-$400 depending on what your looking for
> 
> even a pump up sprayer for decks works- much better
> 
> Just my 2 cents


Umm....its strong enough, because I already did it. 

And by the time it is injected the percentage is barely higher than bleach. Higher Ph, but the acid is going through like 15 minutes later after 50-100 gallons of water have been ran through. 

Even if it kills the injector and gun quicker, the time savings compared to a pump or electric chem sprayer far outweighs the ~$60 for a new gun and injector. 

I use my tools to make me money, not baby them so I don't ever have to replace them.


----------



## Hines Painting

CRS said:


> I have extensive experience in exterior wood restoration. Many exterior stains "penetrating' type can easily be stripped with caustic soda (sodium hydroxide).
> 
> I have set up contractors using a blend of Sodium hydroxide / Sodium Percarbonate / Sodium Metasilicate which makes one of the most effective all around strippers/mold killers/cleaners. Oxalic Acid, or blends of Oxalic/Citric acid are effective neutalizers. Phosphoric is probably the best, yet handling is not near as safe and it is more expensive to use.
> 
> For film build exterior wood finishes, i.e. Sikkens/Timberflex, etc we are gelling the Sodium Hydroxide/ Percarbonate blend. This mix is brushed on and allowed to sit ... basically overnight. Highly effective inexpensive stripper.
> 
> Buy all your chemicals direct, in powder form. My last sodium hydroxide purchase was $.48 lb. Most ready made strippers containing this active have less than 1 lb. of Sodium Hydroxide.
> 
> Use a chemical sprayer. I have helped many set up their own and have experience in the design / parts, etc.
> 
> Feel free to contact me if you would like more info. [email protected]




Unless it is a super thick (or solid color) stain that needs removed, don't you think 1 lb/gal is too strong for most removal? That's about 12% by weight. I know cabot's stripper is 10% by weight; storm system's is 10% by weight, but they recommend a 2:1 dilution (I think, I'm not going to look up the tds) for semi-transparent.

My final mix, by the time my injector dilluted it was about 3% by weight and even that was a little too strong/hot (I would still like to know if it is correct to use "hot" in this instance, if anyone knows).


***Note: I'm not trying to call into question your knowledge on this matter, there are just a lot of lurkers on this site and it is probably best if they don't think they can dump a pound of NaOH into a gallon of water and start shooting it around. Even 10% (which is slightly less than a pound) will definitely give you chemical burns on sensitive areas like your face.


----------



## CApainter

Great feedback Hines!

I've shied away from using chemicals like sodium hypochlorite (in clorox form), because I didn't neutralize them correctly, which created coating failure. I mainly pressure was, or steam clean, just to clean the surface rather than strip. But then again, I don't do wood decks, just mainly concrete or stucco surfaces.

However, I have found the "Juice Box" to work really well as a chemical pump. I have a 100 foot hose on mine, and it operates just fine with a small Honda 2000i generator when utilities are not available. After reading Hines report, I'm inclined to utilize my pressure washer and pump with a little more sophistication. Thanks Hines.


I'd also like to add that I appreciate CRS's knowledgeable contribution to the discussion.


----------



## DunriteNJ

I guess for a house or large area that needs to be stripped it makes sense to DS- just not sure if you can get it hot enough- depends on finish

for a deck or smaller area i would use a dedicated chem sprayer


----------



## ExcelPaintingCo

What type of PPE do you wear when DSing SH? 









?


----------



## Hines Painting

ExcelPaintingCo said:


> What type of PPE do you wear when DSing SH?
> 
> View attachment 26157
> 
> 
> ?



I wore rain gear, a full face respirator, rubber boots and disposable nitrile gloves with a real pair of nitrile gloves over the top.

The store bought jugs of stripper are 10% NaOH and they only chemical burn me on the face. Getting it on the arms will sting a little bit, but doesn't cause any lingering damage as long as you rinse it off.

At 3-5%, once it gets injected, it isn't as strong as the store bought strippers so I wasn't too worried about it, other than my face. 

I was mostly worried about pouring the gallons into a 5 gallon bucket, adding the soap/water mix (because of splash back) since I don't know what 50% would do or how quick; and mildly concerned about getting some of the downstreamed mix accidentally stuck in my gloves or behind my face mask. 

Overall I felt much less at risk downstreaming it than I did applying the store bought stuff with a pump sprayer. 

I'm still undecided if I will keep mixing it myself or order a commercially mixed stripper that is designed for downstreaming. The extra ingredients might help eliminate some of the furring of the wood, but I'm not 100% on that.


----------



## ExcelPaintingCo

This reminds me of a story an old-time food processing employee once told me while we were painting interior walls in his plant. The factory had steel pipes hanging from the ceiling carrying SH to the various work stations for cleaning/sterilizing between batches. He wanted to make sure we didn't stand under a couple areas where the pipes occasionally dripped. Where the drips landed, there were two inch deep by about one foot around holes in the concrete floor. He then told us a story about an employee who spilled some SH in his shoe without realizing. He dismissed the initial stinging sensation because it went away after a couple minutes. However, when he took his shoes off at the end of the day, areas of flesh were eaten away to the bone on his foot. He couldn't feel it because the SH killed the nerves.


----------

