What's the deal with thinning clear coat? Im applying acrylic urethane clear and am interested in trying to thin down the last coat or the 5th coat to see if it lays down flatter or smoother. The tech sheet states not to use mineral spirits so to me that means acetone. I've watched a couple of videos now that suggest this method but they do not elaborate on the ingredients or ratio. But their last coat looks very nice and smooth.
Anybody tried this technique with good or bad results?

Mix your clear coat the way the manufacturer tells you in the TDS sheet PERIOD.If you have orange peel thinning out your last coat will do nothing.So many people think that adding reducer will magically make your clear like glass,wrong....If you use a good gun,proper air pressure, distance,proper speed reducer/hardener you will not have any problems.Spray your clear how you want it to look and do not rely on flow out,most times it will be on the floor if you do.If you do add more reducer to the clear against the manufacturers directions you can expect dieback/loss of gloss,solvent pop,de-lamination(your clear coming off in sheets)

I not having a problem with orange peel I'm just seeing a much smoother final coat when thinned in these videos. It's pretty much a given that normal mix of clear even under the best app will still have some up and down. I'm just wondering if there is a thinning mixture which will help to smooth it out. I'm sure the manufacturers are just gonna provide the mixture ingredients using their products and ratio. Pretty much everything chemical is open to experimentation.

Do you honestly think you can do better playing junior chemist than a multi billion $$ paint company .Manufacturers spend Millions on research and development to find out what works best and what doesn't.It is all technique and proper selection that determines what kind of finish you get,not changing the mix against the manufacturers recommendation. It might look good on a computer screen but might look like **** in person,and most importantly how will it look in 1-5 years?That is the true test ...

use a high quality slow urethane reducer for best results

Here's my advice: Try everything for yourself and come to your own conclusions. My dad has been doing body work for 40 years, my 2 older brothers for about 15 years and me for 2 years. We all do things differently. They have their own styles and technique, I have my own. I'm always experimenting with new techniques, some that I find on the internet, some from coworkers. I can honestly say that in my short experience, my paint jobs will outdo my dad and my brothers paint jobs anyday. Don't let other people's conclusions become your own, the only way to become better at your craft is to always be progressing, learning something new.

Adding a small percentage of reducer will thin out your clearcoat, making it easier to atomize and give it a better flow while its drying out. I do 10% on 4:1 Clears and up to 20% on 2:1 clears. I haven't noticed any problems with the finishes, I have painted like 200 cars in the past 2 years. Too much reducer will without a doubt cause issues though.

Distance and air pressure will do the same thing to atomization as adding reducer with out the drawbacks. If you are in the back yard that is one thing but when it comes to working in a shop spraying 3-8 jobs a day 5 days a week you need to be consistent,changing the mix and going against the manufacturer will result in redos and void your warranty.Who wants to redo things just to experiment?

sure, most clears can be thinned a small amount, but Jay's correct. the only reason clears need to be thinned is because people dont have the knowledge or experience to to properly set up the gun and spray them the right way

Yuuuuuu. On the occasion that im lazy & use my HVLP hun set the psi to the higher side. But that may cause too much over spray.j

Too high pressure can invite side reactions and bring up dirt. As spotless as a booth you work, there will always be some minor dirt. Upping the pressure means upping your material volume or getting dry spray. If material/pressure are not in balance, you'll just get of that orange peel you're trying to avoid in the first place.