Clean, bleach--and sand!
I've used Cetol for years...love it. Armada is a similar product others love...I recommend either. However--as is true of any project, 99% of success or failure is in the preparation. Skimp on that, and no matter how carefully you follow the directions during application, the result will be amateurish instead of the professional "factory" look you want. If you're gonna get the best results, the preparation for using Cetol for the first time is as a big a job as it would be if you were gonna varnish. The wood must be absolutely clean...bleached evenly...totally dry...and sanded completely smooth. Yes...it's a PITA...but the end result looks like hand-rubbed fine furniture. As for the application, I've found that I get a little better result if I VERY lightly go over each of the first two coats with the finest bronze wool before applying the next. That removes any bubbles or brush marks...any slight roughness. Now that you've gone through all this, you'll get to enjoy the advantages of using Cetol or Armada over oil. It lasts a full season in most climates...if you scuff it, you only need to lightly sand and touch up the scuff...no big deal. And next year, you only have to apply another coat--no more teak cleaning, ever. And speaking of next year... I've found that I get better results if I don't just apply another coat,as the directions call for, but lightly "sand" again with fine bronze wool to remove the "top coat" first. That's where any ground-in dirt, UV degradation etc will be...and taking it off, then applying two more coats, keeps that fresh "first year" look year after year.
