It's pretty easy to get the top, bottom and sides of the tank cleaned & coated. The sides of the baffles are a bit more of a challenge since you can't see everything. The only way I know of to be absolutely certain that you get 100% cleaning and coverage is to use one of the services what cuts a hole in your tank to gain full access then welds it back when finished. I cleaned & coated my '38 almost ten years ago and haven't had any issues.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.