This may be under the 'dumb questions' category.
I know that the boil itself should be uncovered. To put it simply, it lets 'bad stuff' boil off. However, is there any harm in covering the wort as it achieves a boil temperature? Also, is there any harm in covering the wort during the chill? I'm aware that it would negate the chilling effect of evaporation, but I think it would greatly reduce the chances of contamination.
I know that the boil itself should be uncovered. To put it simply, it lets 'bad stuff' boil off. However, is there any harm in covering the wort as it achieves a boil temperature? Also, is there any harm in covering the wort during the chill? I'm aware that it would negate the chilling effect of evaporation, but I think it would greatly reduce the chances of contamination.