# What's the ideal bleach % for house washing?



## Damon T

I spoke with my local pressure washing supply company and the guy said he can get me bleach in any concentrate up to 62%!!!
I think pool bleach is typically 12.5 and household is now 8% around here. Downstreaming is typically 1:10 so would 20% be too high? That would really only be 2% on the wall. Most recipes say 1 part bleach 3 or 4 part water and some soap. Which is 25 or 33% yes? 
Otoh I've used household bleach and it seems to work pretty well. 



Sent from my blah blah blah


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## PressurePros

12% is good. Much higher is too unstable and would be hard to store. Twelve percent will burn you nicely and has some hardcore fumes. I can't even imagine handling a 62% sodium hypochlorite solution.

Your mix is going to depend on what you are cleaning. To remove mold from painted trim/wood and vinyl siding, a solution hitting the house of 1.5% is good. I use 3.5 gallons of 12% and a house wash mix with detergent builders topped with water as a downstream mix.


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## daArch

Damon T said:


> I spoke with my local pressure washing supply company and the guy said he can get me bleach in any concentrate up to 62%!!!
> I think pool bleach is typically 12.5 and household is now 8% around here. Downstreaming is typically 1:10 so would 20% be too high? That would really only be 2% on the wall. Most recipes say 1 part bleach 3 or 4 part water and some soap. Which is 25 or 33% yes?
> Otoh I've used household bleach and it seems to work pretty well.
> 
> 
> 
> Sent from my blah blah blah


I've always thought when they said 1 to 3, they were talking 1 part HOUSEHOLD bleach, which would make the final solution about 2% NaClO

That's about what we used when we were hand washing with long handled brushes. (plus the TSP and dish detergent)


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## DeanV

PressurePros said:


> 12% is good. Much higher is too unstable and would be hard to store. Twelve percent will burn you nicely and has some hardcore fumes. I can't even imagine handling a 62% sodium hypochlorite solution.
> 
> Your mix is going to depend on what you are cleaning. To remove mold from painted trim/wood and vinyl siding, a solution hitting the house of 1.5% is good. I use 3.5 gallons of 12% and a house wash mix with detergent builders topped with water as a downstream mix.


So, top off the 3.5 gallons bleach and soap with 1.5 gallons water and downstream away?

Since I switch to pressure tek down streamers I feel like i have not got my mix dialing in consistently. I use liquid pool bleach though and I do not think that quite hits 12%. It seems like I am using more bleach than I used to use for some reason. Probably just pushing more water through with the newer setup as well. I would just be nice to have it down to an exact recipe so the guys in the field do not have to tweak and modify.


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## PressurePros

DeanV said:


> So, top off the 3.5 gallons bleach and soap with 1.5 gallons water and downstream away?
> 
> Since I switch to pressure tek down streamers I feel like i have not got my mix dialing in consistently. I use liquid pool bleach though and I do not think that quite hits 12%. It seems like I am using more bleach than I used to use for some reason. Probably just pushing more water through with the newer setup as well. I would just be nice to have it down to an exact recipe so the guys in the field do not have to tweak and modify.


Yes on your first question, Dean.

I know what you mean. Some guys will go as low as a gallon of 12% on light surface mold on vinyl. I don't want that kind of on-the-fly mixing, so the formula I ran with is a little stronger. The flow of your machine and the size of the downstreamer are all going to affect the final ratio. On some surfaces, especially moldy dryvit, you may need all "bleach" and no water.


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## Damon T

Yeah I guess so Bill. They've recently upped household bleach from 5% to 8%. Billed as Concentrated, it comes in smaller containers for the same price as the larger ones used to be. 
Which reminds me, candy bars have been getting smaller and smaller and more expensive! The regular price is now $1.19 at Safeway for a regular size. What's up with that?!?! 


Sent from my blah blah blah


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## Damon T

So what's the math on that mix Ken? 3.5 gals of 12% bleach and soap plus 1.5 gals water equals X% bleach concentrate. Where's my high school algebra when I need it?! 
Who's got the answer? 


Sent from my blah blah blah


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## PressurePros

Damon T said:


> So what's the math on that mix Ken? 3.5 gals of 12% bleach and soap plus 1.5 gals water equals X% bleach concentrate. Where's my high school algebra when I need it?!
> Who's got the answer?
> 
> 
> Sent from my blah blah blah


Too many variables to even worry about it, Damon. (different gpm machines, true % of sodium hypochlorite, how much hose on a reel, etc).

The perfect percentage is simply the one that works for the job.


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## Damon T

PressurePros said:


> Too many variables to even worry about it, Damon. (different gpm machines, true % of sodium hypochlorite, how much hose on a reel, etc).
> 
> The perfect percentage is simply the one that works for the job.



Thanks Ken!!
I used straight 8% with some liquid Tide added today on a very dirty / mikdewy house and it cleaned up great. Love that 4-tip unit from pressure Tek! 


Sent from my blah blah blah


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## PressurePros

Damon T said:


> Thanks Ken!!
> I used straight 8% with some liquid Tide added today on a very dirty / mikdewy house and it cleaned up great. Love that 4-tip unit from pressure Tek!
> 
> 
> Sent from my blah blah blah


:thumbsup: Makes you think of all those years doing it the hard way.


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## Hines Painting

Wouldn't 5 gallons of 8% bleach be roughly stronger than 3 or 3.5 gallons of 12% plus water? Or is there some other benefit to the 12% I'm not aware of?


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## Damon T

PressurePros said:


> :thumbsup: Makes you think of all those years doing it the hard way.



Too many years!!!! 


Sent from my blah blah blah


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## PressurePros

Hines Painting said:


> Wouldn't 5 gallons of 8% bleach be roughly stronger than 3 or 3.5 gallons of 12% plus water? Or is there some other benefit to the 12% I'm not aware of?


In that example without doing the math.. I'm sure close enough. What if you need a stronger mix though? You have nowhere to go but change the method of application. There is also a cost factor. 3.5 gallons of 12% is less expensive than 5 gallons of 8%. There is a diminishing return in terms of storage time, safety, storage and degradation slope once you go past 15%.


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## bmoorecl

Don't spank me,the info here is great,well outdoor bio Clorox,a clear detergent works great,Man,for some reason after cleaning a house,it leave a clear film,that kills meldew for months, check me, if I'm wrong.love th stuff.


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## Eugene

Just to add another option - How about not using bleach at all?

Here is what a Sunshine Coast Pressure Cleaning company uses:

First we cover the area with our bio-degradable mould killer *which unlike bleach*, chlorine or acids *will clean without causing damage* to the surface and will not harm people, pets or plants.

Here are the results on aggregate









Thoughts?


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## Ultimate

Eugene said:


> Here is what a Sunshine Coast Pressure Cleaning company uses:
> 
> 
> Here are the results on aggregate
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thoughts?


The aggregate looks good. 

The link sends me to a website for a company that provides pressure washing services. I don't see anything about what was used for the disinfection of mold or mildew. Please share what was used to make that aggregate look so good.


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## PressurePros

Eugene said:


> Just to add another option - How about not using bleach at all?
> 
> Here is what a Sunshine Coast Pressure Cleaning company uses:
> 
> First we cover the area with our bio-degradable mould killer *which unlike bleach*, chlorine or acids *will clean without causing damage* to the surface and will not harm people, pets or plants.
> 
> Here are the results on aggregate
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thoughts?


 Hard to say. What psi did they/you use to make the clean spot? Are they/you using hot water? I will tell you from 15 years of experience that quats or sodium percarbonate will not kill mold on concrete in any kind of reasonable time. There are times when we apply a 6% solution and still have to use up close pressure (1200 psi or so at the nozzle is all we go up to) or apply another coating of 6% bleach. As always, the right tool for the job in the hands of a pro for maximum efficiency. Bleach won't damage cured concrete but higher pressure will tear off a skim coat. Aggregate is easy to clean.


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## Alltime

I don't think I've ever run bleach through my machine.. I have a good size hudson sprayer that I've marked for quick fills, 3/1 kills everything I need it to. I give a side or two of the house a pass and by the time I'm coming back to wash all the black has turned yellow. It's an extra trip up and down but has never failed me!


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## Dave Mac

with a down streamer you never run bleach through your machine, and never have to use a ladder for the first four stories look into it, you my friend are chopping down a tree with with a ax, instead you could be using a chain saw. I know because I had that same hudson sprayer and did it that way for a long time.


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## Jmayspaint

Dave Mac said:


> with a down streamer you never run bleach through your machine, and never have to use a ladder for the first four stories look into it, you my friend are chopping down a tree with with a ax, instead you could be using a chain saw. I know because I had that same hudson sprayer and did it that way for a long time.



For real man. I wish I had all the hours back I spent doing that!


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## Acerv513513

The bleach I buy from CSC is 16% good stuff


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## Acerv513513

I use 16% bleach it's easy to store


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## Raptorman

I stopped using Bleach when I found out it does not kill anything. All it does to mold and mildew is the same thing it does to your clothes, takes the color out. To kill mold and mildew you need to use a fungicide, or if you want, straight white vinegar(which will kill about 80% of all molds). Don't take my word for it. Take his. And ask any mold remediation specialist. 

https://www.normi.org/articles/bleach-mold.php


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## AngieM

Wow, great article! Thanks.


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## J R Painting

Damon T said:


> I spoke with my local pressure washing supply company and the guy said he can get me bleach in any concentrate up to 62%!!!
> I think pool bleach is typically 12.5 and household is now 8% around here. Downstreaming is typically 1:10 so would 20% be too high? That would really only be 2% on the wall. Most recipes say 1 part bleach 3 or 4 part water and some soap. Which is 25 or 33% yes?
> Otoh I've used household bleach and it seems to work pretty well.
> Sent from my blah blah blah


Maybe I should have looked into it before I used it, but I got the Splash brand pool bleach at Menards because I saw the 12.5% content. Anyone have any neg. experiences with using pool bleach? I've only used it to bleach out mildew on bare wood. Initially I soaked siding well with it, rinsed at high pressure, but revisited a few spots that could have still used more brightening. I didn't re-rinse yet, but its not too late. With feeding it into my pressure washer downstream, not sure what the concentration is, and also wondering if rinsing is actually necessary. I know the textbook answer is to rinse it all away, but I'm thinking that may not always be true. Esp with bare wood that absorbs. Will there be any residue after a week? Will it evaporate or sun bake away? How well does it rinse off for painting? I only used TSP-PF with the bleach initially, but only pool cleaner on the second go-round. Anyone have some experience they'd mind sharing, I'd appreciate it.


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## J R Painting

Raptorman said:


> I stopped using Bleach when I found out it does not kill anything. All it does to mold and mildew is the same thing it does to your clothes, takes the color out. To kill mold and mildew you need to use a fungicide, or if you want, straight white vinegar(which will kill about 80% of all molds). Don't take my word for it. Take his. And ask any mold remediation specialist.
> 
> https://www.normi.org/articles/bleach-mold.php


What product DO you use? I'd like to know. Thanks!


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## stelzerpaintinginc.

*Rinse the Bleach*



J R Painting said:


> Maybe I should have looked into it before I used it, but I got the Splash brand pool bleach at Menards because I saw the 12.5% content. Anyone have any neg. experiences with using pool bleach? I've only used it to bleach out mildew on bare wood. Initially I soaked siding well with it, rinsed at high pressure, but revisited a few spots that could have still used more brightening. I didn't re-rinse yet, but its not too late. With feeding it into my pressure washer downstream, not sure what the concentration is, and also wondering if rinsing is actually necessary. I know the textbook answer is to rinse it all away, but I'm thinking that may not always be true. Esp with bare wood that absorbs. Will there be any residue after a week? Will it evaporate or sun bake away? How well does it rinse off for painting? I only used TSP-PF with the bleach initially, but only pool cleaner on the second go-round. Anyone have some experience they'd mind sharing, I'd appreciate it.


Nothing wrong with pool bleach, as long as it's Sodium Hypochlorite. Only issue with buying it at big box stores is you'll never really know how fresh it is. Most should be time & date stamped, so look for the most recent dates. But even checking the dates won't tell you how it's been stored, whether it's been subjected to too much sunlight or heat, both of which will degrade the bleach.

Rinsing the bleach is absolutely necessary. Leaving it on the wood will break down the fibers and lignin quickly. Not rinsing thoroughly will leave a film on a house & windows. Ask any professional pressure washer how much time he spends soaping vs. rinsing and they'll tell you the rinsing is what takes all of the time, but it's an absolute must. The only possible exception for not rinsing bleach would be if you were roof cleaning asphalt shingles, but that's a debate for another day.


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## Delta Painting

Raptorman said:


> I stopped using Bleach when I found out it does not kill anything. All it does to mold and mildew is the same thing it does to your clothes, takes the color out. To kill mold and mildew you need to use a fungicide, or if you want, straight white vinegar(which will kill about 80% of all molds). Don't take my word for it. Take his. And ask any mold remediation specialist.
> 
> https://www.normi.org/articles/bleach-mold.php


Thanks for the read it was very informative. 

I have been preaching that bleach dose not kill mold since I joined this site... :biggrin:


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## finishesbykevyn

Raptorman said:


> I stopped using Bleach when I found out it does not kill anything. All it does to mold and mildew is the same thing it does to your clothes, takes the color out. To kill mold and mildew you need to use a fungicide, or if you want, straight white vinegar(which will kill about 80% of all molds). Don't take my word for it. Take his. And ask any mold remediation specialist.
> 
> https://www.normi.org/articles/bleach-mold.php


I read that whole thing and it didn't say anything about vinegar. Who can afford to spray a whole house down with tea treatment oil.?
Are you affiliated with this organization I'm assuming..


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## SamAlex12

You should be careful while using bleach it may hurt


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## OCDpainter

stelzerpaintinginc. said:


> *Rinse the Bleach*
> 
> 
> 
> Nothing wrong with pool bleach, as long as it's Sodium Hypochlorite. Only issue with buying it at big box stores is you'll never really know how fresh it is. Most should be time & date stamped, so look for the most recent dates. But even checking the dates won't tell you how it's been stored, whether it's been subjected to too much sunlight or heat, both of which will degrade the bleach.
> ...


This is huge. Even when stored in perfect conditions, sodium hypochlorite solution loses 20% of its effectiveness per year. When diluted with water, it can become ineffective in days.


TSRI - News & Views


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## stelzerpaintinginc.

OCDpainter said:


> This is huge. Even when stored in perfect conditions, sodium hypochlorite solution loses 20% of its effectiveness per year. When diluted with water, it can become ineffective in days.
> 
> 
> TSRI - News & Views


In higher concentrations, the rate of degradation is actually much higher. It can go from 15% to 10% within 1-2 months. One of the reasons they add sodium hydroxide to household bleach.

Once I started doing more roof cleaning, I finally bought an Aqua Comparator a few years ago so I could accurately measure the strength of my bleach. Takes all the guesswork out of it.
Aqua Comparator


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