The Roof Cleaning Institute Of America Training & Certification Forum
"Find A Certified Roof Cleaner Directory"

Katy - Memorial Power Washing wrote:

---

I have not heard this mentioned anywhere but SCH's shelf life is affected by 2 things.  Temperature and the UV rays of the sun.  In other words, store it in a cool place out of the sun and away from any heat source.  ie not on the South side next to a wall in a building.  I keep my chemicals in blue plastic containers that I get from my distributor.  It keeps the UV rays and the heat out.  They also carry black & clear tanks but I do not use them.  The UV rays pass through the clear ones too easy and the black ones absorb heat. 

I am from Texas and the season for us started in February.  Yes it was cold, 40 deg and windy, but when the customer calls and wants their roof cleaned, in this economy, we jumped on it.

---

Interesting reading ?
Bear in mind the SECOND example deals with the Disinfecting, NOT cleaning propertys of SH for Roof Cleaning !!
We WANT SH at HIGHER PH's for cleaning roofs.
This is because the cleaning properts, NOT the disinfecting propertys are enhanced
at HIGHER PH's, and so is the shelf life.

How do you ensure adequate shelf life of SH?

Sodium hypochlorite is highly reactive and volatile. At normal pH (6-8) sodium hypochlorite can degrade substantially within 2-3 weeks. This shelf life is not adequate for use in the SWS, for the hypochlorite must remain at high enough concentration to inactivate disease-causing organisms. By raising the pH of the hypochlorite solution, you stabilize the solution. The pH can be raised by the addition of sodium hydroxide, which is widely available. In order to determine the amount of sodium hydroxide to add to your sodium hypochlorite solution, you will need to complete trial-and-error testing. Add a known volume of sodium hydroxide to a known volume of sodium hypochlorite, and then measure the pH with a meter or kit. Because source water quality is different in each location, there is not one standard volume of sodium hydroxide to add to ensure pH is above 11. You will have to start with a known volume (perhaps 1 tablespoon in 1 gallon, or 5 ml in 1 liter) and complete iterative trial-and-error testing. The exact pH is not important in this context - you simply need to ensure that the pH is above 11.

Top

4. Will adding NaOH change the effectiveness of the SH?

No, because when the sodium hypochlorite solution is added to water, the water decreases the pH and the sodium hypochlorite more active. The chemistry behind this is: the pH scale is from 0 to 14. Acids have a pH below 7, bases are above 7, and 7 is neutral. Most natural water is around pH 6-7. When sodium hypochlorite is in water, it breaks up into two compounds, with the concentration of each compound dependent on pH. One of these compounds is significantly more reactive, volatile, and more effective at inactivating bacteria than the other. At high pH (above 11) the majority of the sodium hypochlorite is in the form of the less-reactive compound. Thus, when you add sodium hydroxide to the sodium hypochlorite, you are converting it into the less-reactive form. However, water is around pH 6-7. When you add a small amount (5 milliliters) of solution at pH 11 to a large amount (20 liters) of water at pH 6-7, the mixture becomes pH 6-7. Thus, when you add the hypochlorite at pH 11 to your water in the SWS, you convert the hypochlorite back into the reactive form, and then it inactivates the disease-causing organisms.

 

Katy - Memorial Power Washing wrote:

---

Apple Roof Cleaning Tampa 813-655-8777 wrote:

---

The addition of either some Caustic Beads, OR liquid 50 percent Sodium Hydroxide will extend SH shelf life some.

You only need from 1 to 2 percent in your roof cleaning mix for a bit longer shelf life.

---

Where are you getting Caustic Beads from Chris?  I went to my SCH supplier and he said that they don't sell it.

 

---

I use liquid sodium hydroxide sometimes, never caustic beads.
But several here also pressure wash, and use the beads.
Where they get em, I dont know ?

 

Raystown Roof Cleaning Central PA 1-800-236-0322 wrote:

---

You can get caustic beads or flakes at any chemical supply. But for small amounts you can also go to Lowes and get a drain cleaner product called "Roebics" It is like 2 lbs. for around $8.00. Same exact thing as the caustic beads you buy in bulk.

Jeff

---

GOOD to know Jeff
The addition of 1 to 2 percent Sodium Hydroxide will extend SH shelf life a bit.

 

Hi Rich and Welcome to the board,
I had the same problem with Univar, the closest one to me that packages and sells is the one near Jeff in PA. The one here in Baltimore only does Pesticides. I spent a lot of time looking around (check the phone book and Google) I ended up paying a litlle more then I wanted but get a barrel for $232 after tax deliverd!. Unfortunettly I have a barrel Deposit on top of that. The price is $4.20 after tax and shipping per gallon, but I cannont find it around here for under $2.75 and would have to drive over an hour to get it then wrestle it off my truck into my garage or transfer it to another container. Many of these companies only sell in tankers and sell to repackers. I called manufacturing plants to get their sales office #'s who gave me the repackers #'s.

Rich, be SURE it is FRESH SHC ?
Dont pay 2.59 a gallon for salt water !!