We are building a log house. First, using a garden sprayer, I mixed 75% poly with 25% thinner and applied with the sprayer and brushed it out. The next coat was about 90/10, applied the same way. The final coat was full strength and applied by brush. The house was about 70 and the Poly had been in the house for about 3 days. We applied it, admired it, checked it for runs, brushed out a few, then quit for the night. The next day we could have cried, runs on every wall. Any ideas? I suspect I may need to thin out the final coat or warm it up to about 80 to thin it more.