Table 3. Growth Resistance of Unpigmented Resins 



Resin Tested 



Acid No. 



A. pullulans 



A. ovyzae 



A . nigev 



Totals 



1 original 



54.7 



2; 1 



2; 3 



2; 2 



12 



1 organotin 



- 



5; 5 



5; 5 



5; 5 



30 



2 original 



25.7 



1; 1 



1; 2 



i; 3 



9 



2 organotin 



- 



5; 5 



5; 5 



5; 4 



29 



3 original 



6.6 



0; 1 



0; 1 



0; 



2 



3 organotin 



- 



2; 2 



2; 3 



2; 2 



13 



4 original 



5.7 



0; 1 



0; 



0; 



1 



4 organotin 



- 



1; 2 



2; 4 



2; 2 



13 



5 original 



4.8 



0; 1 



2; 2 



1; 2 



8 



5 organotin 



- 



3; 1 



5; 3 



5; 4 



21 



Totals 



39 



52 



47 



138 



It was expected that growth resistance ratings would be much greater 

 overall for the pigmented than the unpigmented resins because of the 

 pigmentation dilution of the nutrient content of all the resins and the 

 tin content of the organotin resins. However, this did not occur in all 

 cases. A. pullulans grew most abundantly and A. ovyzae least abundantly 

 under the test conditions. A. ovyzae enzymes degraded the paint films 

 even when the growth on the film was sparse. This suggests that 

 enzymes diffused from the agar where growth was heavy onto the paint 

 film. Large zones of growth inhibition on the agar suggest leaching of 

 toxic tin compounds from the paint film. 



In another test, blends were made of each of two organotin resins 

 (Resins 1 and 2) with their original resins, and the resistance to growth 

 of these blends was determined. It can be seen from Table 6 that decreas- 

 ing the tin content generally decreases the resistance to fungal growth. 

 In a final variation, blends of the organotin linseed oil ester in Table 

 1 and two of the organotin resins (Resins 1 and 3) were tested for resist- 

 ance to growth of A. pullulans. It can be seen from Table 7 that the 

 addition of 10% organotin linseed oil ester to organotin Resin 1 and 20% 

 to organotin Resin 3 completely inhibited growth on the paint film and 

 produced a large zone of inhibition on the agar. 



