Clear Coat Problem

[Mowe]

Hope someone can help me out with this issue.

Recently clear coated a new projected using HOK UC 35 Clear. There is a total of 8 coats shot on in 3 different sessions. At first I noticed 2000 grit scratches that were difficult to buff out using 3M extra cut compound and red foam pad. The finish appeared to be very hard. Over night I left the fender on it's side. I checked the next day and noticed the terry cloth towel left an imprint on the fender, which required more sanding buffing to get rid of imprints. I also tested with the tank and other fender and am getting the same result.

I am always careful to follow mixing ratios and guidelines on P Sheets. Although the Hardner was opened previously in hot weather, it was clear and free of cloudyness.

I have tried oven curing at 125 degrees for one hour and am still having the issue of the clear being imprinted from laying on a cloth.

Should I consider scuffing and laying a coat of UFC 35 over existing finish.

Have contacted HOK twice but they have not yet returned my call, can you offer other tips or suggestions to resolve this issue of a soft clear coat.

 

[hoss]

i think too much clear was applied maybe at one time. here is the thing, if you shoot too much uc35 at one time it won't cure properly. instead of getting hard it will stay jelloie undernieth and never cure out properly.

this might be the problem. What catalyst did you use? ku100, ku150,?

 

[Mowe]

Hey Hoss
I used KU150 and never went over three coats at one time. Gave at least a week before reshooting. I wet sanded the top of a fender last night with 1500 to open up the surface and baked up to 140 degrees for an hour. I'll test it today to see if that will help. I've got a lot of graphics on this set and hate the thought of having to strip it down and redo. ........Moe

 

[purplemyth]

had this happen to a tank about 2 months ago. It was due to a severe weather change between base coat to clearing.
If the top cures off too fast, the underside never gets to evaporate fully and as said, it will be soft. Ours was still imprint~able for weeks. We finally had to totally strip ours and redo it. A good eye on the weather and the proper mixes are always needed.
good luck~

 

[Mowe]

Thanks for the info Purplemyth. I used a cardboard box and a 250 watt infrared light to bake the set ( one piece at a time ) after sanding with 1500 grit to allow better flash off. It seems to have worked! Our local powder coater wanted $150.00 to bake them. The box and light worked just as well at a fraction of the cost. I really think my problem was old hardner in one of the mid coats of clear. In the future I'm going to toss any hardner over a month old thats been opened.................Moe