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TOPIC: Clear cracking!

Clear cracking! 01 Nov 2019 17:34 #813409

  • ErlingW
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Hi guys!
Have You ever experienced the clear shrinking and cracking like it did here? This is 10 layers of clear, and they started cracking two days after the last layer was sprayed.
What's Your thoughts on this?
https://scontent.fsvg1-1.fna.fbcdn.net/v/t1.0-9/75439327_10216717193776354_6217272869596954624_n.jpg?_nc_cat=106&_nc_oc=AQn0rZtC3LEeqiqHPy9uAFvnnB3mZRNsyHTzTO9XFgMuczYfynx04HFreDfA49GaXm0&_nc_ht=scontent.fsvg1-1.fna&oh=20684a51da75919b3f3ea1a89d750c22&oe=5E1AF66C

Regards, ErlingW in Oslo, Norway

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Clear cracking! 01 Nov 2019 19:13 #813413

  • KZQ
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I'm not very experienced on automotive finishes but if you were to spray ten layers of lacquer on a piece of wood the finish would gain enough stiffness and strength that when it eventually shrinks it will over power the bond to the lower layers and crack just as your picture shows.
If I'm wrong someone with more knowledge, please chime in.
Bill
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1968 BSA 441 Shooting Star, 1970 BSA 650 Lightning, 1974 W3, 1976 KZ900, 1979 KZ750 Twin, 1979 KZ750 Twin Trike, 1981 KZ1300, 1982 KZ1100 Spectre, 1987 Yamaha Trailway, 2000 Valkyrie, 2009 Yamaha Roadliner S. 1983 GL 1100
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Clear cracking! 01 Nov 2019 20:03 #813416

  • SWest
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This is the crack.
Z1b1000 1975 Z1b
Opinions expressed by me do not reflect those of the the staff or members
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229
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Clear cracking! 01 Nov 2019 21:05 #813417

  • DoctoRot
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is the crack to the primer? Typically cracking is a bi-product of material incompatibility
-Vic
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'78 kz1000 LTD long term project

'80 kz750G project
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Clear cracking! 02 Nov 2019 00:28 #813420

  • ErlingW
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Unfortunately, yes! I think I saw signs of that when sanding away the cracks last night. Still no signs of green metallic in the sanding paper though.
The primer, base paint and clear are all products from the same brand, and should go well together. Not so sure about the sprayfiller. Alle these products may be a bit on the "cheap" side. Maybe that's where my problem is? I'll do another respray of the clear today, and see in a few days if it looks better. If it doesn't help, at least I'm on the right side of winter...LOL

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Clear cracking! 02 Nov 2019 14:10 #813458

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if its cracking adding more paint will not solve the problem. You need to strip to the substrate that is failing. How long did you wait between coats? All paints are different, following the instructions for flash times is super important to ensure a chemical cross link between coats, otherwise there needs to be mechanical abrasion between coats. did you seal the spray filler before going to other topcoats?
-Vic
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'78 kz1000 LTD long term project

'80 kz750G project

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Clear cracking! 02 Nov 2019 14:15 #813459

  • SWest
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Had the same problem, too many coats. This is better.
Steve
Z1b1000 1975 Z1b
Opinions expressed by me do not reflect those of the the staff or members
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Clear cracking! 07 Nov 2019 06:42 #813669

  • PaintWorkz
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Always good to strip away all old paint before you prime, even factory paint since they did not seem to even use primer. If you spray acrylic lacquer colors or clear too heavy and without enough dry time it will probably crack in a few weeks. The first couple cars I sprayed with a pressure pot did that.
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