Trying to avoid the same mistake - base wrinkled

mhouston

New Member
Hi All, new forum member here. Just a hobbyist, and been using the SPI epoxies and other products on my project for about 18 months now and finally got to the point of throwing color on it after years of rust repair and metal work. Made a mistake that is essentially going to require me to sand off all my base and start over and I want to make sure I don’t make a similar mistake.

Took the week off work to make sure i had plenty of time. Got my doors, fenders, and other bolt on parts sealed, based, and cleared early in the week- all turned out great. Then moving on to the main body:

The surface going into the process is a combination of well cured SPI epoxy and 2K primer (sanded through primer to epoxy, 2K left in the low spots). Everything was sanded to 400 grit - shooting a solid color so no need to go further.

Anyways i started out with a reduced coat of epoxy for sealer, about a 30% reduction (1:1:~0.7). Sprayed that out in one wet coat and let it sit for between 2-3 hours. Then started base. I’m shooting shopline base (only thing I could get my paint code in) and activating with SPI universal activator. I sprayed 3 fairly wet coats with about 45 minutes flash between coats. I noticed on the 3rd coat some very fine wrinkling/crazing so that’s when I called it quits. After talking with a few people over the last couple days the first line of action was to let it sit overnight and sand out the wrinkles back flat and then shoot a couple light coats of base to see if it would take it. It did not- started wrinkling almost immediately after sanding with 1000 grit. It seems that i probably made 2 mistakes: I did not wait long enough after spraying epoxy to start base and the base solvents soaked into the epoxy? Second is I may have sprayed base a little to heavy. or it’s a combination of the two.

Anyways, given this is a restoration type project for me that I want to last a long time I’m going to sand off all the base and start over since it seems the problem is with the sealer or first coat of base. So here is the plan once I get to spraying again if you guys can confirm my approach makes sense

1)day 1: spray reduced coat of epoxy as a sealer (25-30%). I’ll probably spray around 7or 8pm. I’ll then wait overnight
2) day 2: spray activated base on unsanded sealer around the same time in the evening (~23-24 hours later). Most likely 3-4 coats with 30 minute flash times
3) wait overnight and spray clear 24 hours later the following evening.

I’m out of time on the time I took off work so this will have to be an evening and early morning type project now. I’m willing to adjust accordingly. I’ve attached a photo of the type of wrinkling that I’m dealing with. It seems to occur in areas and sections of panels that I would naturally have a tendency to lay it on a little heavy or have an overlapping coat- this is what is making me believe that the problem is with the sealer timeframe.
 

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Solvent is definitely attacking what is below and not just your sand through area.
Need more information in order to help resolve this issue:
As stated already the temperatures of the booth and metal.
Name of products used: 2k, reducers, base, activator, etc.
Speed of activators and reducers would help.
Did you use wax and grease remover or a tack cloth?
Also, are you sure you mixed the 2k properly?
 

mhouston

New Member
Solvent is definitely attacking what is below and not just your sand through area.
Need more information in order to help resolve this issue:
As stated already the temperatures of the booth and metal.
Name of products used: 2k, reducers, base, activator, etc.
Speed of activators and reducers would help.
Did you use wax and grease remover or a tack cloth?
Also, are you sure you mixed the 2k properly?
All products are SPI other than the shopline base itself, yes I’m sure that all products were mixed correctly. I should add that I’m using about 1 oz of universal clear activator per 26oz cup of already reduced base. Oh and all products are “Slow”

Metal temp stayed in the low 70s for all coats, air temp in the mid 70s. Lowest metal temp I recorded in one spot was 68 degrees. I did tack between sealer and base but not between coats of base. No wax and grease once the sealer was applied the first go-around. I did wipe lightly with some to clean up the sanded areas while trying to fix it in round 2, but the wrinkles showed up before that

The reason that I’m thinking the sealer application/timing is the issue is that I followed this same process with excellent results 3 days earlier with the only exception being that I previously let the sealer sit overnight due to how late I sprayed it that day. I’m also thinking that maybe I sprayed the base on heavier this time but that could just be in my head
 

crashtech

Combo Man & Mod
I don't have any experience with Shopline or this new poster, so I am going to sit out for a while and let this shake out.

In the material I use, the only time this happens is if the epoxy is applied too thick or at too low a temp, and/or not given enough time to dry.
 

texasking

Promoted Users
In my experience, I have seen the Shopline base do strange things that no other base does. Spraying it heavy is asking for problems. At this point, I would spray 2 coats of unreduced epoxy to really seal off what you have. Introducing more solvent may cause it to lift again. Time is your friend. Wait as long as possible to let the epoxy cure before sanding, then proceed with a reduced coat of sealer, base and clear.
 

mhouston

New Member
So it seems the general consensus is an issue with the sealer coat, whether it be too thin or thick or just not enough time before base. I could seal it up with more epoxy and wait. Can I accomplish the same thing by sanding it back down to the epoxy sealer coat (remove all base), refinishing to 400 grit, waiting a few days, spray a single coat of say 25% reduced epoxy and go straight to base?

I will most likely end up sanding through to metal on a few edges since the base in on all the jambs as well, so I may need to spray the epoxy unreduced, then wet sand the flat surfaces to prep for base
 

Chris_Hamilton

Trying to be the best me, I can be
Follow what Texas said above. Spray 2 coats unreduced. Give it the proper time to cure, sand it and then shoot a single coat of reduced epoxy for your sealer. Wait 4 hours minimum then base.
 

mhouston

New Member
Thanks for the help guys I will spray 2 coats tomorrow evening- I’m assuming I’ll need to scuff it to 180?

If I target shooting base again next weekend that would be 4 days of cure before shooting sealer- would that be long enough? I’ll be able to keep it above 70 that entire time.
 
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