| p>In part one, we discussed what causes the black | | | | ingredient in bleach, it works well at removing algae |
| stains on asphalt roofs that is so often found on | | | | and mildew. As found in bleach it is around 5% by |
| houses especially in the Southern United States. Now, | | | | volume depending on the brand. Commercial Clorox |
| we will discuss two of the techniques of removing | | | | brand is around 6%. Bought "off the shelf," 5% |
| the stains and why one way should be avoided. | | | | bleach will clean a roof but it will take some time and |
| There are generally two ways to remove | | | | probably several applications. |
| Gloeocapsa Magma. Either with Sodium Hypochlorite | | | | The problem with store brands is the 5% is really not |
| or Sodium Hydroxide. This is where the debate | | | | strong enough and Sodium Hypochlorite loses |
| begins. Some contractors use one and some use the | | | | strength over time. It is hard to tell how long the |
| other. So what is the difference and which is the | | | | bleach has been setting on the shelf and you can't tell |
| best? Here are the facts. | | | | the strength until it is used. You may have noticed at |
| Sodium Hydroxide is a chemical used in many | | | | the "dollar stores," the bleach is weaker than at the |
| different products and applications. Some of the | | | | grocery store. The reason is because the bleach has |
| better know are dish washing detergent, water | | | | been pulled off the grocery store shelves because of |
| treatment plants, oven cleaners and paint and stain | | | | it's age and sold at a cheaper price at the dollar |
| strippers. It is also used as the main ingredient in roof | | | | stores. |
| cleaners sold at the big box stores. | | | | Most professional roof cleaning contractors will buy |
| Used as a roof cleaner it is applied usually with a | | | | their Sodium Hypochlorite from a chemical supplier. It |
| pump up sprayer to the roof and allowed to set for | | | | is fresh and also much stronger at 12.5% content by |
| a period of time. Then using some type of pressure | | | | volume. Applied correctly, it is an excellent cleaner |
| washer someone will get on the roof and using | | | | and does not harm the shingles. It is the only method |
| pressure, wash the chemical and stains off. As it is | | | | endorsed by the American Shingle Manufactures |
| being washed off it looks like syrup or coffee running | | | | Association. |
| off the roof. Some of this is the algae, but some of | | | | Sodium Hypochlorite is caustic so precautions must |
| it is also asphalt from the shingles. | | | | be taken when being used. It will kill grass and plants |
| As mentioned earlier, Sodium Hydroxide is used in | | | | if not properly applied and, it will also corrode metal |
| oven cleaners and dish detergents. It is actually an | | | | and can etch glass if not used correctly. Safety |
| excellent degreaser. It breaks down grease, oil, etc. | | | | precautions must also be adhered to. Chemical mask, |
| to a substance that is water-soluble and easily | | | | gloves and protective clothing must be worn and |
| disposed of. We use it to remove oil based stains | | | | run-off controlled. It is not for the homeowner, the |
| from decks. In this case, used as a roof cleaner, it | | | | do-it-yourselfer or an untrained contractor. It is |
| does remove the algae, but also kills grass, plants and | | | | however the best method of removing Gloeocapsa |
| can damage glass as well as break down the asphalt | | | | Magma. |
| (oil based) in the shingle. It does not destroy the | | | | So although there is a debate as to the best method |
| shingle because of the chemical's strength and time | | | | to remove the black stains from roofs, like most |
| left on the roof, but it does remove some degree of | | | | anything else, there is a right way and a wrong way |
| asphalt. And any amount of asphalt removed is too | | | | to do anything. Know the facts and you will know |
| much. In my opinion, not the best method. | | | | the right way. Roof cleaning can be done safely and |
| Sodium Hypochlorite is another widely used chemical | | | | effectively if done correctly. Those are the facts. |
| in roof cleaning. Probably best know as the main | | | | |