I understand the cans of color may have components that settle out, especially metallics, so periodic shaking while applying is needed, but what about clear. Isn't that pretty uniform so a quick shake is enough.
Well, if its a clear coat in a can, it has no catalyst and no pigment, nor metallic, "Aluminum" flakes or chips really. Clear and solvents, or reducers is all you have so shake for a minute and let it stand for a few minutes for the air bubbles to settle, and I don't see the need to shake as you spray.
Yes you still want to shake it. Even though there are no pigments (color), you still have 2 components that need mixing -- the stuff that creates the dry film (exact name eludes me) and the solvents.
If you just go and spray a can that's been sitting without shaking, you'll likely spray just the solvents which will evaporate into nothing as if you'd never sprayed. I notice this when spraying clear, if you don't shake, the consistency comes out like water (just the solvent), whereas when mixed you get the thicker paint consistency that will leave an actual finish without it all evaporating away. Imagine the same concept applies while spraying, you probably want to give it a shake every now and again to keep the components mixed well.
For the extra minute or two that it might take to shake it thoroughly, is it really worth the worry?
Many times I will shake a newly-purchased spray can in the car at stoplights and such if I want to spray something immediately when I get home.
Shake well, and spray away.
I like to warm the paint up a bit first in spray bombs if possible. I use a pot of water hot to the touch, <span style="text-decoration: underline">not boiling</span>. Put the can in for a few minutes, dry it, shake it and spray the paint. It makes for a better job I found.
You do realize that, much like most paint, there are components that will settle out and need to be disbursed, especially since there is no way to know how long that rattle can has been sitting idle.
As my wife would say, "bless your heart".
I always warm the can in hot tap water, builds up pressure and flows better. For clear, after a little shaking I kinda swirl it around every now and then so as to not create bubbles but still mix it. Works for me.....