A trick I found out with the hammer paint was to use a black primer with the supposedly black hammer paint. The hammer black paint actually looks more like a dark charcoal grey. First, I sprayed the primer, let it dry, then sprayed a coat of the hammer rustoleum paint. Doing so gave me a nice effect thus avoiding any thick and running spots. Trying to get good coverage with the hammer paint alone ends up to thick and runny. My best advice is experiment.
