Cleaning a fan on a gravel roof ... Bring a rake and remove the gravel from around the fan.. Then clean the fan , place a 5 gallon bucket with some pea gravel in in under the spout get the chuncks out the will stay n th 5 gallon bucket drill little holes in the bucket beneath gravel level so the clean water can drain.. Then clean the underside of the fan ... after your done , dump the grease junks in a grease vat and re spread the gravel around the fan bringing some new gravel into the area also.. Then take your 5 gallon bucket , put some clean gravel in it with little holes at the bottom of the bucket ... I do this now with all my customers as an added on free of charge service with a 3 month hood cleaning contract... No mess and easy to clean... On white rubber roofs we use lava rocks in the 5 gallon bucket , it works really nice...
I suppose you could go get some foam padding like they use at walmart or home depot and put it in a 5 gallon bucket..