While I look forward to Jim's return and responses I will chime in here at length regarding many of the topics brought up in this thread as well as the thread recently posted by Pete Marentay regarding bleach. Jim and I have had our go rounds about the misuse (not so much use) of bleach in the past and it seems that every winter this subject pops up. For the record, I hold Jim in high esteem and in my opinion his knowledge regarding wood restoration is second to none.
First, chlorine is the most used chemical and with that being stated it is also the most misused chemical. I am sure we have seen examples of such when performing estimates as well as visiting locations in our day to day lives. Secondly, it is a fact that chlorine breaks down the lignin (glue like substance that holds the wood together) separating it from the pulp. The biggest example of this is in making paper products. However, with that being said the "true" guru of wood restoration and the industry as a whole was Sam Williams of the Forest Products Laboratory who have determined the standards for the industry. According to the Forest Products Laboratory they recommend deck cleaners but also a "home recipe" of Soap, Household Chlorine Bleach, and Water. I know for a fact that this is how Sam used to clean his own deck. The reason they say household bleach is that in studies it has been documented that 3% bleach content was enough to kill mold and mildew on wood surfaces. Please refer to page 11 of the following document,
http://www.mchd.com/pdf/woodpr.pdf .
Now to address the uses of bleach and quite frankly most other chemical usage. I feel a lot of inexperienced and new folks to the business misuse chlorine bleach. It could be because of the contractors who clean roofs that use a higher concentrate of bleach to clean roofs and merely use the same solution on decks. Please do not say this does not happen because I see people post that they do this all the time. I also think that even in house and building washing that higher solutions are used more often to avoid climbing ladders, aid in soft washing, and to get the job done quicker. The extra money spent in chemicals offsets the time in labor. These heavier doses of chlorine bleach is not necessarily good for the wood but we need to take a closer look at each job and what the desired out come is. I have always recommended and always will that the least amount of chemicals used to get the job done is the best method. I don't care if it is concrete cleaning or wood restoration. If you can get away with hot water only on concrete to get clean it is better for the environment. If we can restore the wood with an oxygenated bleach instead of chlorine bleach then I believe that is the best method. The issue however that complicate these situations is ultimately neglect and lack of maintenance. In these cases we need to look at cleaning and restoration on an individual basis. We have all heard of the good, better, and best methods to accomplish an desired outcome and we need to apply that in these situations. Let's take concrete first where we may have a well maintained property that only requires periodic frequent cleanings with hot water, then we have a so-so maintained property that requires light chemical usage, and poorly maintained property with heavy mold, mildew, dirt, debris, rust, gum etc. that need an arsenal of equipment and products. This is the same in wood restoration regarding how well maintained the wood is. If the wood surfaces are well maintained and we can use an oxygenated bleach, brighten, and re-coat then I am all for it. If however the customer has not maintained it according to guidelines and it is say 2 to 3 years past re-coating it may need a diluted content of chlorinated bleach to effectively kill of the mold, mildew, moss, lichen, whatever to achieve the desired results. If it has been poorly maintained it may need that arsenal of products and equipment. For example, I have done decks and wood homes where we had to use a sodium hydroxide based stripper to remove everything from surfaces and STILL had to bleach to kill mold and mildew spores that were deeply embedded in the wood. This frequently happens with wood that has been neglected over 10 years. Remember, bleach reacts with the first thing it comes in contact with so if there is a real heavy build up this may be the "best" method to get the wood back to where it will be consistent and clean for re-coating and preservation. Regarding cedar roofs and any other wood surfaces, I have never met anyone from the wood industry at the Forest Products Lab or the Manufacturers that would suggest cleaning the wood and NOT putting some type of preservative on it. They would tell you you were better of leaving it alone. With that being said there are exceptions to EVERY rule and Ipe would fall into this category.
Think of it in terms of medicine and an illness. There are many different types of medicines and doses a doctor can prescribe. One doctor may prescribe one medicine and dosage for the same illness that another doctor may prescribe a completely different medication and dosage. The result being you get well as an outcome. In taking the medicine as prescribed you are following recommendations and if you aren't getting better the doctor may increase the dosage (Sound like bleach usage?). One thing for sure though is that you are not supposed to take the whole vial of medicine at one time thinking that if you did you would immediately feel better. An overdose is obviously too much and with wood and concrete alike an overdose of chemical usage. We have all seen property owners go right for muriatic acid when it wasn't needed and seen the damage. Same can be applied to misuse of both sodium hypochlorite and sodium hydroxide in wood. I have seen burned and furred up from chemicals mixed too strong and left on wood surfaces too long. I have seen bleach misused more times than I can count from "white" wood, "tie dyed" wood, and furred wood.
In regards to brightening and oxalic acid, I strongly believe in using it in every situation because it serves three purposes, not one. First, the most desired reason is that it "brightens" the wood and is a must after using a stripper. Secondly, it is excellent in neutralizing iron and metal stains, If you are using bleach and lighten the wood especially on a fence, you will expose these stains even more prominently effecting the end result after sealing or staining. The third, is that it opens the pores of the wood and helps with penetration of the products. Think of concrete restoration, it is always recommended to acid etch the concrete to open up the pores of the concrete before re-staining or dying of the concrete. Same principle in wood restoration.
In summary, we need to understand that in wood restoration (as it is in other areas of cleaning and restoration) that each job is evaluated on an individual situation. There are times when a heavier does of chlorine bleach will need to be used because of the neglect of maintenance. What we need to become better at is educating ourselves as to what is enough to get the job done and what is too much. I personally do not clean or strip any job if I am not putting a coating on it which is how I run my company. Sorry for the long response but I thought one was needed, please let's have a civil discussion regarding this topic though as I have seen this topic go in different direction too many times. I will say that I do love seeing the results of so many of my friends and peers on these boards knowing that we all do not perform our services exactly the same!
He markets a soft wash without any SH. The best of both worlds.
