I am an industrial coatings salesman with 42 years experience in selling to OEM-type accounts, but I am also on the architectural review board of an 80-unit, high-end townhouse development. I can't find a solution to a problem concerning extreme mildew on our painted, cedar-sided townhouses. They are approximately 11 years old, well-insulated, and are painted every four years with top-quality stain.

The painting contractor claims that the solid-color stain contains a sufficient amount of mildewcide in the formula, and the surfaces are pressure-washed prior to each painting cycle. However, after about two years, the mildew returns with a vengeance and seems to be worse as time goes on.

My townhouse has now been painted for the third time, the last time being two years ago, and the mildew is terrible.

We are located in a suburb northwest of Philadelphia and receive the normal amount of rainfall for this region. It does not matter whether the exposure is north, south, east or west, it all seems to receive the mildew condition equally. I would appreciate any suggestions you may have in resolving this problem.

Excessive mildew is perplexing because I live in Peachtree City, GA, an area of high humidity that certainly promotes mildew, yet I do not see nearly that much of a problem here. The normal practice before repainting is to spray any mildewed surface with dilute bleach to kill all fungal organisms and then rinse with water.

After having that much problem I'd consider switching painting companies, but that may not help. The occurrence equally on all sides is not normal; the south side, which has greater sunlight exposure, usually shows far less mildew. I wonder if the siding itself can be causing the problem. Could it be that moisture is constantly trapped behind the siding? Even so, I wouldn't expect to see so much mildew.

All I can suggest is to remove a small section of the cedar and treat it with bleach or other fungicide before repainting. Be sure that water is not held behind the boards. If this treatment reduces or eliminates the mildew, it should be apparent in 10 to 18 months, at which time all siding can be refinished this way.

Blowgun's Silicone Lube Causes Craters

I wanted to pass along a tip that may help others when struggling with fisheyes (craters) on painted parts. Our company is a large manufacturer of wood cabinetry, and employs around 1,700 people. With this many employees, it is very difficult to control the use of silicone-containing personal care items (antiperspirants, hand creams, etc.), but we make it a priority. Our policy is to send an employee home for a shower if found to be "contaminated."

A discovery was recently made that we think has contributed to fisheyes for a long time. A technician on one of our finishing lines noticed that fisheyes seemed to be coming from the use of a brand-new air gun used to blow off parts prior to topcoating. Discussion with our blowgun distributor and manufacturer showed that these popular metal air guns have a seal that is prelubricated with silicone.

Our distributor was able to supply us with a new type of gun made in Switzerland and apparently very prevalent in Europe just for this fisheye-avoidance reason. Side benefits of this OSHA-approved plastic blowgun are that it is half the weight of the metal ones, operates at a much lower noise level and does not mar the surface of our parts if accidentally lightly brushed against them. Also, the cost is competitive.

I found your information interesting and will pass it along to our readers since it is clearly genuine. The presence of silicone lube will obviously be detrimental to most finishes.

Occasionally I receive equipment or product information from a salesperson pretending to be a user. They always give the brand name and state that they found whatever item they are touting "amazingly effective and better than anything like it on the market." I noted your e-mail address, which reflects that your company is indeed involved in painting wood products. What also added considerable credence to your letter is the fact that the brand name of the blowgun was not given. The reduced risk of damage from plastic versus metal may be beneficial to a number of plants.