Do people use carbon paste on carbon bars going on standard alloy stem or are they unlikely to slip if all torqued correctly?

If so, do you just slap a bit on the face plate?

Yes, that’s exactly what it’s for.

When you apply it make sure it covers the full circumference of the bar where it meets with the stem and faceplate (not just under the faceplate).

I’ve also heard said that the extra mechanical ‘grip’ the paste provides means you can use slightly less torque than the stated max Nm for the carbon bar.

+1

https://www.bikethomson.com/wp-content/uploads/2015/10/MtnBarInst.pdf

+1 more.

I don’t use carbon paste because all of my carbon bars have a textured area where they are clamped in the stem so I didn’t think it necessary

I use paste as above, and also on top of any textured area on the bars themselves. It’s one part of the bike that I dont want any issues with when hitting some terrible line choices through rocky sections!

Ordered some so will get my bars sorted this weekend!

As above (Renthal Carbons) have a rough textured area so not needed with those.

I’ve also heard said that the extra mechanical ‘grip’ the paste provides means you can use slightly less torque than the stated max Nm for the carbon bar.

Scariest thing I’ve seen written today!

I would also suggest you get the paste without the micro granules in it so if you move bits around it doesn’t sound like sand paper grating which can cause cosmetic marks on posts/bars etc.

The stuff I use now is like wallpaper paste. Got it after recommendations from here. Good stuff and non abrasive.

I used the grainy stuff once, creaked like hell once it had dried out a bit. Don’t bother with anything now, just torque up as spec’d.

What make did you use poop, got a link please?