possible alternatives must be taken. The first of these is to allow each paint 

 job to progress relatively far into a state of disintegration, even at the expense 

 of appearance, before repainting. The second alternative is to apply succeeding 

 coats sparingly as they are needed to preserve appearance and then to remove the 

 paint down to bare wood at 15 to 20 year intervals. 



A suitable program of maintenance for white lead paints is to repaint with 

 one coat every three years or to repaint with two coats everj' eight to ten years. 

 Repainting V7ith mixed pigment paints cannot safely be done more often than once in 

 four years with one coat or once in six or seven years with two coats. 



The repainting of well weathered surfaces should usually be done in two coats. 

 The priming coat should be applied at the rate of one gallon for each 400 to 500 

 square feet, and the finish coat applied unthinned at a rate of approximately one 

 gallon for each 700 square feet. 



When repainting mildly weathered surfaces or those in good condition, one 

 coat will usually be adequate. Apply unthinned paint at the rate of about one 

 gallon for each 600 square feet. 



In any paint maintenance program repainting should be done with paints that 

 are compatible with the finish coat of the previous painting. If there is any 

 doubt concerning this point, consult the paint manufacturer's literature or other 

 reliable sources of information. 



Moisture Build-Up In The Woo d. Fairly frequently paint falls due to an increase 

 in the moisture content of the wood under the paint film. This sort of failure is 

 characterized by blistering and will occur even on surfaces v;here good paint has 

 been used correctly. 



Moisture may gain entrance due to faulty flashings around openings, cracks in 

 the siding, around trim boards, etc. It may also pass in vapor fomi from the 

 inside of the building, then condense on cold surfaces within the wall cavity. 

 The control of humidity conditions within the building will help to prevent the 

 passage of moisture through the walls, but in severe cases it may be necessary to 

 provide a vapor proof membrane to retard the passage of moisture. Two or three 

 coats of oil base paint will often reduce moisture passage to a tolerable level. 



If moisture penetration is the cause of paint failure, the only solution is 

 to find the source from v/hich the moisture comes and correct the situation before 

 repainting. 



J. T. Clayton 



Professor 



Agricultural Engineering 



I I I I I I I I I I I I I I I I 



PGMOLOGICAL PARAGRAPHS 



Weed Control . A grower pointed out that if you were spraying an area 3 feet from 

 the trunk on big trees, the actual square footage sprayed would be more than if 



