how many coats equals too many?

[Hugh Kininmonth]

we use the HOK range and i am wondering how many coats we can apply before we lose strength in the finish. particularly in regards to making the finish susceptable to stone chipping. talking here about painting bikes.

for example.......just doing one colour with the PBC's, with no graphics the HOK recommendation is........

two or three coats of primer, a couple of sealer, two or three of the PBC and then another two or three of clear over it all. so we are looking at between 8 and 11 coats just for one of their basic finishes.

if it is kandy and complex graphics, then it quickly rises.

does anyone know what harley use? their paint jobs don't suffer much from stone chips.

thanks in advance.
hugh.

[Jon E]

I went to a HOK training class and the rep swore that as long as you used 100% HOK materials that the millage build up was "unlimited". He had a sample front fender that he brought that had over something like 30+ mills on it and beat it on the desk without chipping it.

That being said, I try to keep everything as thin as possible but the better the materials that you use, the less trouble you will have with chipping. The best Ive found to hold up agains't rock chips and "assembly damage" are R-M and PPG (only with activated basecoats) with DuPont being by far the easiest to chip. I wont even use DuPont anymore because of it.

With the HOK, just be sure that you put it on wet, give it plenty of time to flash between coats and don't pile on any extra material that you dont need and you should be fine.

[Hugh Kininmonth]

many thanks jon. that is exactly the information i was looking for.

we may be putting on a little too much material. i have started to notice that the bikes we paint seem a little more inclined to suffer stone chips than the harleys we service with factory paint.

hugh.

[vadimb]

The best Ive found to hold up agains't rock chips and "assembly damage" are R-M and PPG (only with activated basecoats) with DuPont being by far the easiest to chip.

Are you saying the R-M base coat without activator, with the same clear will be easier to chip than the R-M base coat with activator, and the same clear?

Would you explain how the base makes a difference like that?
Thanks
Vadim

[Jon E]

Are you saying the R-M base coat without activator, with the same clear will be easier to chip than the R-M base coat with activator, and the same clear?

Would you explain how the base makes a difference like that?
Thanks
Vadim

Vladim,

It's been my experience that activating the basecoat improves the chemical bond between the basecoat and clearcoat, as well as improving the adhesion of the basecoat to the primer itself. If I remember correctly, you add 5% of DH46 (clearcoat activator) to the reduced basecoat. When the clear is applied, the activator in the base reacts, or "cross links", with the wet clearcoat to form an additional chemical bond between the two that would not normally be there.

Even without activating the basecoat the R-M is still very durable, but for the projects that I work on, I think the small expense to activate the base is cheap insurance. It's even required by severial different auto manufacturers to meet their warranty requirements.

Hope this helps,
Jon