I use a pressure washer being careful not to use more pressure than neeeded........Too much pressure will remove some of the soft teak..........Areas that cetal is not easily removed should be removed using a second pressure washing.....Let the wood dry before the second washing.
I too will be starting over with new Cetol next spring on the toe rails, grab rails, drop boards etc. However, a pressure wash sounds like a very bad idea. You will most likely end up eroding the soft grain of the wood by using this technique and require a major sanding operation to make the wood ready for another application of Cetol or varnish. There must be a more controlled and precise way of removing this stuff without the "Bigger Hammer" approach of "sand blasting" it off. Some other ideas out there?
I agree that pressure washing is a very bad idea. Basically you have a few choices; each has its ups and downs. Cetol is tough stuff. 1. Sand it off. 2. Use a heat gun and scrape it off. 3. Use a chemical stripper. As evidenced by what the pros do, sanding is best. Heat guns can drive substances into the wood and chemicals can damage wood and the gelcote. Good luck.