Very bad crinkling when intercoat applied

[Kevin R.]

I’m working on a friends 2013 Avalanche left rear wheel arch rust out. The last coat of intercoat clear had a very bad reaction and approximately 50% of the panel checked. ( I kept the repair area very small- within 2” of wheel opening). The truck is in my paint booth with the windows blacked out to eliminate UV issues. Slow reducer was used in intercoat clear and base coat. My process to date:
1. Cut out rust and welded in repair sections around the wheel arch, approximately 1/3 of the circumference.
2. 2 coats unreduced SPI epoxy primer to all sanded bare metal (80 grit).
3. Polyester filler applied and sanded to 180 grit.
4. 2 coats unreduced epoxy primer to repair area.
5. Block sanded epoxy to 320 grit.
6. Sanded entire quarter panel to 800 grit to prepare for blend and new clear.
7. 1 coat 25% reduced epoxy sealer to repair area including slightly into sanded OEM. Blocked with 320 grit.
8. Final coat of 25% reduced sealer over repair to cover burn thru’s.
9. 1 coat of intercoat over entire quarter panel.
10. 3 days later, Denibbed and painted 1 additional coat of intercoat clear as a blending bed. Waited 1.5 hours to flash.
11. Laid down 2 coats of Sherwin Williams Ultra 7000 base coat with Sherwin Williams activator. Waiting 1 hour between coats.
12. Extended blend with 50% basecoat/50 intercoat. Each component was mixed 1:1 with their matching slow reducer. Both activated with their respective hardeners. Waiting 1 hour between coats.
13. One final coat intercoat clear to cap off metallics. Everything looked great. See photo.
14. 20 hours later, Found a small sag in basecoat and sanded out. (2” x 4”). Sprayed sanded area with basecoat using an air brush. Let flash.

So far everything looked fine, but bad things were about to happen.

15. 1 coat of intercoat over entire panel and was planning on clearing tomorrow. About 50% of panel immediately checked. See photos.

I’m at a loss where to go from here because I can’t figure out what the issue was that caused the reaction. I used this same process on my 1973 Mustang last year after discussing it with Barry and all went well. See photos. Any help figuring out what happened and the process to recover will be appreciated.

Thanks
Kevin

 

[Rich796]

You can not spray a activated base coat. Over a non activated ( catalyzed ) intercoat/blending clear. It will wrinkle up every time. And, you also can not spray non-catalyzed intercoat blending clear over an activated base.

 

[crashtech]

If I counted right, you got 7 coats of base on there. That to me is massively excessive for a 2-stage panel repair. 7 coats is normally reserved for a 3-stage job, even then, it's still a lot, most guys spraying solvent base try for 5 coats or even less if possible. The other thing I notice is that Ultra 7000 is a modified enamel, and SPI Intercoat is a polyester. So there my be some degree of incompatibility there. I never mixed the two directly together although long ago I did spray Ultra 7000 and used SPI intercoat sometimes. I'm sorry to say that Ultra 7000 is ancient, crappy base coat. What may have happened is that during the days spent layering all this material on the vehicle, the Ultra actually started to kick off (crosslink) because of the presence of isocyanate in the reactive reducer and its enamel heritage. Hitting a material that has begun to catalyze with a coat of relatively hot polyester base (intercoat) will cause exactly what you see.

Really I have to say that it seems as if you made the repair more complicated than it had to be. If you were anticipating metallic control issues, one coat of straight intercoat activated with clear activator on the whole panel is plenty. Then just cover the repair area with base, fanning the coat out into the unrepaired area until coverage is achieved. That's it. With a color like that, I would not have anticipated blending problems, even with Ultra 7000. No intercoat on top of the basecoat is required or desired. Wait overnight, then clear. It's the K.I.S.S. principle. Adding unnecessary complexity is begging for trouble.

 

[Kevin R.]

Thanks for the fast reply. This was my first blend attempt and mixing the intercoat with the base 50-50 seemed strange to me, but recommended on all the blending advice including the SPI intercoat sheet. Besides too many coats it looks like the basic differences in the Ultra and polyester may be the root cause and that’s what I was looking for. I’ll keep it simpler on the next try. Do you think the painted areas that didn’t wrinkle need to also have the base removed? Should I continue to activate the intercoat on the next attempt? Thanks again!

 

[Rich796]

When you cut your BC with intercoat. It's to help transition your blend area. If the BC is a very good match its not always needed.

 

[zachm]

Ultra 7000 is kind of a weird basecoat I used to spray a lot of it and your suppose to use their reactive reducers with it I’m guessing something didn’t play well together if I remember correctly ultra 7000 has a pretty short potlife once mixed

 

[crashtech]

Thanks for the fast reply. This was my first blend attempt and mixing the intercoat with the base 50-50 seemed strange to me, but recommended on all the blending advice including the SPI intercoat sheet. Besides too many coats it looks like the basic differences in the Ultra and polyester may be the root cause and that’s what I was looking for. I’ll keep it simpler on the next try. Do you think the painted areas that didn’t wrinkle need to also have the base removed? Should I continue to activate the intercoat on the next attempt? Thanks again!

Personally I don't think that job needed or needs Intercoat at all, but if you must, use 1 coat only as your first coat, and activate it. I'd be a little concerned that you might need to prime the areas that wrinkled once you sand them, I'm sure you'll have sand-throughs between layers that may show later if not primed. But priming over a thick application of base carries risks too.

 

[Chris_Hamilton]

I have gone into a LOT of detail on how to do a blend. Multiple times here. Might be helpful to you. And get rid of the house paint and use a proper modern polyester basecoat. Seriously. SW is garbage. Spend the money and get something decent. Motobase is priced really well and is lightyears better. Worth it just for the ease of use. I promise.

Did this a while back. Might not be perfect but it covers a blend repair fairly decently. Would be worth reading for the correct way to do it. Or at least how I have done it for a long time and been successful at it. If you have questions feel free.......

How to blend paint to repair and match existing paint.

Hi all. I figured I'd do this write up as both Crash and I thought we needed to have something here on the forum to refer folks to when asking about blending. I'll try to outline the proper technique to prep, and how to do a basecoat blend. Single stage the same principle applies. In this write...

www.spiuserforum.com

 

[crashtech]

If he still has some of the Ultra 7000, it can be used imho. The one saving grace of Ultra is that it's not very "hot," it can be applied over sensitive substrates with less chance of a reaction. I just don't think it plays well with the Intercoat. BTW, there is this little disclaimer in the Intercoat tech sheet:

This Intercoat Clear works with all high-quality base systems. Lower grade systems should be spot tested before using.

Although, testing of that days-long mixing and layering procedure you used would be difficult...

 

[Kevin R.]

I appreciate the feedback. This will be my last SW paint. It’s not a money issue, but an availability one. SW and NAPA, which is the same thing, are the only jobber I could find in Fort Wayne, IN that a diyer can go to for a color match. One way or another I’ll find an alternative.

I sanded the wrinkled areas with 800 on a da this morning. Appears to only be in the last intercoat layer, I did break thru in a couple small areas to the SW. I’ve hand sanded the panel with 1000 followed by a white scrub. It looks pretty good. My plan is to shoot a light coat of base over the areas that wrinkled and into the blend area. If that goes well then I’ll universal clear tomorrow. I’ll post how it goes.

Thanks

 

[crashtech]

Be careful applying base over sanded through layers. it's not considered best practice.

 

[Chad.S]

I appreciate the feedback. This will be my last SW paint. It’s not a money issue, but an availability one. SW and NAPA, which is the same thing, are the only jobber I could find in Fort Wayne, IN that a diyer can go to for a color match. One way or another I’ll find an alternative.

I sanded the wrinkled areas with 800 on a da this morning. Appears to only be in the last intercoat layer, I did break thru in a couple small areas to the SW. I’ve hand sanded the panel with 1000 followed by a white scrub. It looks pretty good. My plan is to shoot a light coat of base over the areas that wrinkled and into the blend area. If that goes well then I’ll universal clear tomorrow. I’ll post how it goes.

Thanks

I used to be a Sherwin dealer and purchased all of my inventory through the Fort Wayne store. Renee that runs the store is awesome but the products are not so much. I am thankful to have made the switch.

If you want to mail me things I can mix and ship things to you. Closest I get now to that area is Sturgis though.

 

[Kevin R.]

I used to be a Sherwin dealer and purchased all of my inventory through the Fort Wayne store. Renee that runs the store is awesome but the products are not so much. I am thankful to have made the switch.

If you want to mail me things I can mix and ship things to you. Closest I get now to that area is Sturgis though.

Thanks Chad I’ll keep that in mind. Do you know of a PPG jobber in the Fort Wayne area?

 

[Kevin R.]

I’m now through the wrinkle issue and I thought I’d let everyone know what was done. I appreciate the feedback and guidance through this issue. First I sanded out the wrinkles and prepared for paint. I purchased a shortwave IR heater and set it up about 3’ from the panel so it could cover most of the quarter panel. I turned the heater on and let it heat for 1 minute, then stepped in front of the heater and layer down a light coat of base over the area that wrinkled. Stepped back and left the heater on for 1 minute longer. No wrinkles returned. I repeated the process with an orientation coat over the entire panel. The next day sprayed 2 coats of Universal Clear. I plan on final polish in a couple of days. Thanks again!

 

[Kevin R.]

My major lesson learned was not to use Sherwin Williams. I plan on Chad’s in Troy Michigan for fixture projects.

 

[crashtech]

Also don't overuse Intercoat. If you'd just used S-W and left the Intercoat on the shelf, you'd probably have been okay. Talk to us before coming up with a procedure if you're not sure.