to tape or not to tape:
While everyone has their own process, and will work at different levels, circling back to the OP's original question was:
Which is was the focus of my original answer. Providing a reference in Mike Phillips book, The Complete Guide To a Show Car Shine, Page 111 where he discusses the proper techniques of taping off, and type of tape along with the benefits. He then links a video on youtube, which was provided in the thread, where he demonstrates taping off an older 911. Thus, OP's question answered.
As far as should you, or not? That's a different subject/topic/thread and each person will have a different answer and reasons. However, since the question came up, I tape off for several reasons.
1.) you may not run into the issues we have here in AZ, where temperatures can reach 100+ the rubber trim and or plastics can become very dry. Likewise, some products and heat will do nasty things to rubber and plastics. Some products could potentially dry out the rubber. Worse, you spend so much time focusing on the paint, that you forget to remove the spread off the rubber/plastic and in the heat, it dries making it nearly impossible to get off. Taping allows me to focus only on the paint...
2.) Should your pad hit the black rubber, take a look at the pad after. You will see it too has turned black. When maximizing time spent on paint, we want to minimize contaminants getting on the pad and transferring to paint. This holds true for your polish removing MF towels. I want to keep the towels and pads on the paint. Use a separate spent towel/pad (if polishing a-arms, b-arms, black plastic etc...). So if you do want to polish pastic, that's fine.. use the spent pad/towels for that.
3.) While most products i.e. Speed, GG BOSS can be trim friendly some are not... Spending the time to re-cleaning those areas is time consuming, worse case you miss a spot and the customer sees it. Which brings up another point - listen to your customer, each one has different concerns. My last customer made a point to talk about how good his trim looked (and it did...). We wanted to protect it and make sure we didn't waste valuable time later since the trim was of high importance.
4.) Some vehicles come back for spot buffs, like the R8 with paint splatter I recently did, which already had DLUX, Some trim had to be retouched, but most of it didn't. My mustang will get re polished this fall, but all the trim looks great, and it too also has DLUX. Redoing these items, will be an extra expanse in time and money that isn't required. A short roll of tape will fix that.
5.) Protecting raised edges: We'll use 3m thin red-line tape for the old "rule of thumb trick" that Mike showed me. If you're going to be working on an older classic car, where there are raised body lines, the paint will be thin. I use this thin red-line tape as my demarcation... using my thumb tip to measure out where the body line starts and where to place the tape. This stops me from going over the thin spots. This trick also works good on newer vehicles with vinyl graphics.
6.) We also tape off emblems and badges to prevent any edges catching our pads. Working on classic cars where the badging is delicate, usually just two rivets holding it in, I don't want to be that detailer who has to explain that to the customer. Taping the emblems, badges and name plates also cuts down on time as we don't have to spend as much time with q-tips getting into those spots to get the compound residue and dust out. Lastly you don't want your pad to catch a sharp edge and ruin the pad.
Interior Gal and I can have a car taped in less than 5 to 10 minutes. It's not a big show stopper... but is sure is a big life saver on time and appearance when the customer gets the car.
Typically if working with strictly HD Speed, may not tape off as I admit, Speed works great on plastics... It's just the pad I worry about... But dedicated compounds and polishes, certainly do. But with speed, I always use a pad that's about to go into the snappy clean bucket for any pads that will run over rubber trim. B-Pillars are a different story, but again, I use the spent pad so we don't transfer any gunk.
Lastly, like all the tools in the tool box, polishers, pads, compounds, etc... tape is just another tool in the tool box. Use it or not, it's up to you!
