Most types will get soft again by soaking,often with some soap in water,by wetting a blanket or sheet and lay it on,after a time check to see if it has soffened up,an then wash off.
More Compound on a soft towel , the coarse cut often burns into the paint and merely washing it off will leave tell tale pattern of where it was . polishing it off is the best way to remove the evidence. = my way
If its spatter thats slung off your buffer, how about pressure washing it as lightly as you can get by with or hose it and wash with soapy sponge lightly then go back over everything lightly by hand??? Not sure if this is a good reccomendation, Ive done this just enough to get into trouble but I do know the dried compound will scratch your paint if ya dont get it off carefully. Does anyone actually use swirl remover after the buffing is done or is it just a quick fix crutch to cover up a less than perfect buff job or to get that little bit of extra shine just to get it out the door and make a customer happy at first sight, cause I dont think it last long if its not done rite underneath it??? or is it suppose to also be like a polish enhancer or??? It still doesnt seem to stay long.....
Have you tried regular mineral oil (not the same as mineral spirits), as used for wooden kitchen cutting boards ? Or furniture 'lemon oil' ? I use either to soften and apply my buffing compounds, as they dry up in storage over time. I use Naphtha (aka lighter fluid) for clean-up after buffing. I use this on even the most delicate fine wood oil finishes, which are far more sensitive and softer than car finishes.
I'm a professional detailer. I've done it for about thirty years as a living in Los Angeles and now here in Seattle. I see this often in my line of work. People who can afford to have nice high end cars, whether they built a hot rod, or went out and bought a nice new Porsche, and then do a terrible job detailing the ride. I hate to see a great car with white build-up in all the corners. I hurts my eyes!! The best way is to re-do the job, by HAND! No buffer for this kind of work. Spend the day with your car, getting to know it, feeling the paint and curves with the product as you buff. After a while you will notice the paint start to feel different and start to squeak. Products to use: Meguires Rubbing compound (one of the nicest products I have used that is affordable $10). Clean bar towels (WalMart sells the 12 pack for $4.00) Masking tape (3M blue) Mask off all chrome or moulding that is next to paint to be waxed. This is important to do because you need to get all the shit out of the cracks. The application of the new compound usually works out the old dried stuff and dirt. Important to spin the towel as you work the wax near the crack so not to scratch the paint and create lines from dirt particles. Work the cloth into the edges and spin the cloth! You will see dirt on the cloth. Sometimes you will see paint color. It's done when it squeaks. The masking tape is for easy cleanup and so the compound or wax does not discolor black moulding or other textured surfaces. Then use a soft toothbrush and lightly work any areas that has any leftover wax. Should look like a real polished gem after that. **Sorry..but some of the suggestions are not good ides. WD-40 will work its way under decals and stick-on pin stripes etc. Best is to stick with car related products. I've seen many bad $5 dollar remedies ruin $5000 paint jobs.
This reminds me of the guy that did the $3500 detail on the Astin martin on Gas Monkey, I thought it was gonna get X rated when he started rubbing the leather seats down with the oil....... (I know it was dramatized) But I guess that enthusiasm about what he does is why he makes the big bucks, It did look amazingly like a different car when he was done but still original. Just joking around there, I admire what some of you guys can do, Thanks for sharing the info.
@John SSS has it right. but I would emphasize taping/papering ALL gaps,cracks and crevices. It's best if it doesn't get in there in the first place. Don't let it dry, clean it before it dries. it is MUCH harder to clean it up later, but if it does like John says use fresh compound and rub it by hand. I really really REALLY hate this stuff after it has dried.
I use spray detailer, like Mother's, or Meguiar's to soften the wax residue, then a soft nylon tooth brush and micro-fiber towels to remove it.
If we're talking metal polishing compound,best suggestion so far is rubbing alcohol. I've used it on brass, aluminum and stainless for years. Alcohol and toilet paper works every time.