Pressure Washing Paint Prep With Bleach

plazaman

I am getting mixed reviews on this... is running bleach through the machine bad? What affect does bleach have on a surface like wood?

Why do painting contractors use bleach when power washing? Mold & mildew?



Ive always used water and no chemicals for all my washes.



What about this other stuff TSP?

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daArch

"Common" practice dictates that exterior surfaces should be washed with bleach and a "non-ionic" detergent. (non-ionic, to the best of my knowledge means a common dish detergent like Joy, Palmotive, Dawn or similar). Other directives indicate TSP with the bleach.

Chlorine bleach kills mold and mildew (as does alcohol). The detergent (or TSP) cleans off other dirt and grime)

Rinse THOROUGHLY. Although chlorine dissipates, the detergents need rinsing.

As far as running bleach through a machine, bleach is a powerful oxidizer, so if you have ferrous metal parts (or other parts negatively affected by oxidizers) I would surmise that bleach may not be so good for the parts in a machine that are negatively affected by an oxidizer, like iron or aluminum. I'm not sure on the long term effect on brass, but I think it is safe)

Bleach on wood, in my experience, never harmed the "cell structure" of wood, but it has changed the color (it has "BLEACHED" it - imagine that ).

I got out of the painting business before the wide spread use of power washers and spray guns. We always washed the exteriors with long handled "dairy brushes" and a thorough rinse with the hose.

Power washers are very effective because of the concentrated stream. Not only do they blow the dirt and mildew off, but also loose paint.

My opinion is that if your machine will not be adversely affected by bleach, then use it.

just thoughts

-Arch

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jackrabbit5

You should be able to get a downstream chemical injector for your machine. Downstream meaning that it is attached downstream or on the output side so the chemicals never actually go through the machine. The way they work is you put a tube from the injector directly into a jug of bleach and when you use the special large orifice tip it causes a drop in pressure and allows the bleach (or whatever chemical you are using) to be siphoned out of the jug. Switching back to a regular tip ceases the siphoning. The problem I've had with mine is that the stainless check ball would more often than not stick after being in pressure mode.

plazaman

So I mix the TSP with the bleach or use them separately for different applications?

Does TSP or bleach harm vegetation? What about skin contact?

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jackrabbit5

You can mix them. Vegetation should be wet down prior to application and rinsed well afterward as well. both bleach and TSP are hard on the skin, if you get it on you rinse it off ASAP.

bigchaz

High pressure isnt always the answer. The right chemicals allow houses, roofs and wood to all be cleaned with very little pressure. Bleach will harm your pump. Use a downstreamer instead. Bleach will kill plants, grass, etc. Rinse well

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Charlie Soden
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"New life for old wood"
Deck cleaning and staining Wake County

daArch

As the others point out, bleach and TSP is no good for humans and vegetation. I had one worker whose hands blistered after a day of washing - he refused to wear the rubber gloves.

My personal choice would be to prevent contact with skin and vegetation than to rinse off after contact.

One advantage to the "old" way of washing with a brush, is that you can limit contact of your wash solution to only the siding and ground immediately beneath - where most people do not have vegetation.

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plazaman

Any substitute detergents instead of bleach and tsp? I would hate to use something that is harmful to my employees.

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gideond

Sodium Percarbonate would be my choice. Many store bought deck cleaners use it now. Currently I'm selling Wolman DeckBrite. There is one you can order online called Restore-a-deck. This stuff is an oxygenated bleach, not a chlorine bleach. No need for additional detergent either and it's much safer on plant life. It's also classified as a mold killer so there should be no concern in that area when not using chlorine bleach.

slickshift

Not surprising
In reality bleach is not the best answer
But it can work
You need a machine set up for it, or set your machine up for it
Some use it (on everything) as it is simply easier to use the same mix on the whole house/deck etc.
It's not really the best way to go, but some will swear by it as it does "work"

I use bleach only when needed, for mold/mildew
I'll spot treat (jomax/bleach/water) if possible, or hit the whole North side (or whatever) if needed
I use as little chemicals as possible - none if I can get away with it
But I live out in the ocean in the land of rust and mildew
So I have to use mildecides occasionaly
However, I also live in an area where the Environmental Police (EP) are armed, and as they are not part of the actual Police Dept., don't have to follow Police protocol when chasing or shooting someone
Needless to say, I use chemicals sparingly
Effective
Helps give the new coat some tooth also
A TSP/Bleach/Water mix can be effective, used sparingly, and have a small environmental impact
Must be rinsed well though

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Originally Posted by ModernStyle I have never used this crap before and I pray to the paint gods that I never have to use it again, I would rather use Behr

slickshift

I have been using more of this on home prep
(started using it on decks)
It seems to work well

(Also doesn't stink like bleach so less H/O spaz-outs)

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gideond

Yep also good on vinyl siding and concrete!

plazaman

is there a special kit i have to buy for my PWer to downstream? I never ran any chemicals before.

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welovepainting

Most high quality or professional grade pumps have them. Its pretty simple you plug the clear house into your machine put the other end into the solution and the solution only sprays when you have the wash (black) tip in your gun.

jackrabbit5

Here is a link to one of many places you can get one. Or you can do a Google search for "pressure washer" "chemical injector".
http://www.cmcpwe.com/accessorycheminjectors.html