How to know when you need a new bar of clay?

[nissenc1337]

I've been using a mothers clay bar for about a year now. I've clayed two cars with it and some spot claying as well. It stays in a zip lock bag with clay lube to keep it from drying out. I kneed the clay before using and I find it fairly effective but I've got a brand new bar waiting to be used and wondered when or how do you know when an old bar is used up?

[Klasse Act]

I was going to say you know when you try a Speedy Prep towel!

Sent from my SPH-M930 using AG Online

[c8n]

Not sure if I am correct on this or not but I downgrade clay to windows duty when it changes in color or when it starts to feel coarse

[Klasse Act]

Not sure if I am correct on this or not but I downgrade clay to windows duty when it changes in color or when it starts to feel coarse

That's not a bad idea actually but becareful on the glass still, I'm sure you are;-)

Sent from my SPH-M930 using AG Online

[imranhakro]

From my personal experience there are two factors that decide longevity of clay bar:

1) Amount of bonded contaminants on surface,
2) How quickly clay bar detoriates ("crumples") away.

So, it really becomes a judgment call as to when it's loaded up to the point where you no longer want to use it.

[hernandez.art13]

I watch these all the time, because they are good videos:

http://youtu.be/gfxAesk4Po4

http://youtu.be/qoyGSo0ekXc

[HateSwirls]

I normally play it by eye, if the clay begins to darken I save it for my wheels.
One way to know for sure it's done is when it begins to falls apart or sticks to the paint and hard to remove.

I did this truck once, had to throw a bar just doing the hood, sometimes you just know:)