Plumbing. I am trying to seat pvc male treads into a brass female end for a utility tub faucet.?

If you want to have both hot and cold water at the tap, I'd recommend changing plans to using CPVC, rather than PVC which is only for cold supply. Then you can also get CPVC "transition" fittings that can be glued/solvent welded on the pipe and end with a brass pipe thread. Then there's how you start this new run from your existing system. If copper, and adverse to soldering, look into compression fittings. (Hint there: if you have "nominal" 1/2" copper, look at 5/8" comp.)

Teflon is used as a lubricant is some applications and even as artificial ice for ice skating (Hockey, Figure, Recreational).

Teflon is also widely used in seals and is a replacement in many cases for plumbers goop to seal threaded pipe fittings.

You should never screw Male PVC threads into any metal fitting. The Male threads often crack and break off.

Purchase a brass close nipple with the same size and threads of the brass female fitting. Also purchase the correct size PVC Female fitting.

Teflon tape both ends of the brass close nipple. Apply the Teflon tape in a clockwise direction so when you screw the brass close nipple into the brass fitting and screw the female PVC fitting onto the brass close nipple the Teflon tape will not tend to unravel.

I'm not an expert, but have repaired a fair number of things over the years and my observation is that the metal male threads will taper and the plastic won't. If you insert the tapered threads into plastic each turn of the fitting is going to increase the pressure leading edge of the female plastic. Maybe you will find the ideal amount of tightness. If you get it too tight then maybe somebody bumps something into the pipe and then it splits. If you insert the plastic into the metal any tolerance issues will stay constant, a sealant would be needed, but nothing is trying to break anything. PTFE tape is not a sealant in the same manner as a glue or silicone that cure, but it still seals by plugging the threads.

Teflon tape will work by itself as a sealant, however if you really want to make sure that you get no leaks, use about 3 wraps of Teflon tape first then apply Spears Blue 75 over the Teflon tape. this combination we have discovered makes a really good seal and wont leak under most cases. Spears Blue 75 is specifically made for PVC pipe threads.

http://www.spearsmfg.com/prod_brochures/BLU-2-0200...

I buy it at an irrigation store in our town.

I would use teflon tape and a pipe dope or paste.

when wrapping the teflon tape around the threads make sure the tape is going with the threads. then use your thumb and or finger to compress the tape. Place into the assembly and make sure the threads start without cross threading. remove now apply the dope and reassemble

I would under no circumstance do as Comp-Elec suggests my comment to his answer below

I disagree going with a male plastic mtp thread into brass ftp thread is far better than what you suggest. The real issue would be to be careful of cross threading. Most east to crack and break is what you suggest brass male onto female plastic as it cracks when over tightened

Pvc To Brass