Last summer (2009) we applied two coats of an exterior latex water base deep red paint (clear coat base) to lightly textured, previously painted wood siding on our house. The house had been spray painted very pale green about 10 years ago. The surface was in good condition and only needed a light sanding and primer in a few places prior to our paint job. The white blotches, mostly about a foot long by a few inches wide, began to appear (and disappear again)shortly after we completed the paint job. The blotches are almost transparent and have appeared off and on on all four sides of the house. Is this still part of the ‘curing’ process or, if not, what would cause the blotches?
This should not be part of the "curing" process. If you purchased the coating at a paint dealer, you need to inform them of the problem.
I am troubled by your description of the (clear coat base.) To me this suggests the problem could be a colorant issue which would need to be handled by the coating manufacturer.
If you did not paint over a dirty surface, it is most likely a product issue and should be taken care of by the manufacturer.
Please do not be frustrated into not staying in contact with the retailer. Squeaky wheel gets the grease. After the first contact, give them a week to 10 days to come and view the problem. I would suggest calling on a regular once a week schedule until the issue is resolved to your satisfaction. All manufacturers have a line item for warranty claims and expect to have to service their products. Stick to your guns, be firm yet calm and you will get results.