Activating base?

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440A-body

This is kind of a two part question. Please forgive me if this seems elementary to you guys, but I have not been able to comprehend this for some reason.
A little history, I have been doing bodywork and restoring cars as a hobby for over 20 years, and have never activated base coat. Frankly I have never
heard of doing it until about a year ago.

Now for that question. Why should it be done and what are the benefits to doing it? I have never had any problems in the past by not doing it.

The reason I ask is, I am getting down to final sanding on a friends 84 Camaro drag/show car. Did all the bodywork then primed it with Slicksand to
get it level (must have went through a hail storm), blocked it with 180 and applied SPI highbuild for final blocking down to 400 wet. We will be applying
SPI white sealer, and using (please forgive me for this ....he already bought paint) Omni base in color called Clapton Green. Then cleared with
UC, then cut and buffed.
 
Basecoat is by far the weakest link in today's high end systems, typically every product is catalyzed except for the basecoat. Anything that can be done to improve the performance of the basecoat should be welcomed by those who wish to do quality work. Several of the benefits of activating basecoat include improved adhesion to the substrate, improved flexibility, increased chip resistance, and better resistance to wrinkling in the event of a repair. Barry might be able to go into more technical detail, but most manufacturers agree that basecoat activation improves the properties of the product, and many make it mandatory for the refinish of flexible parts.
 
Thank you! I appreciate the answer, that makes total sense in the grand scheme of things now. I will be doing this on the Camaro then.

However the Omin MBC base tech sheet has no activator listed for it. What would you recommend?
 
Take a look at the tech sheet for DBC, it recommends 5% DX57 in many situations, which is just an isocyanate activator. I haven't personally used MBC, but it's likely to be similar to DBC. The Universal Clear you are using has an isocyanate activator that can be used the same way as DX57. The usual recommendation is 1-2 ounces per sprayable quart, and 1 1/2 ounces per quart is just slightly less than 5%.
 
O.K. with that being said,I'm getting that I can use the UC activator with out harm, or should I use MH169 Omni clear activator? If I use the Omni will I be asking for trouble when the SPI clear is applied (such as a compatibility issue)?
 
i have used UC activator in DBC base for a while now with no issues but never in omni. PPG wants around 40 bucks for that small can (i think half pint) of DX57, thats just ridiculous.
 
I've used the spi uinversal clear hardener in omin and it works fine. Only need about 2 oz to a thinned qt.
 
i catalyze everything. all my base for prob 8 years now. i had some cheap job recently on some bs part so i had some black limco base which is an acrylic enamel basecoat. boy i'll never do that again. the cat actually half kicks the limco so anything you put over it wrinkles it like a sob. with that said it my fault for not using a good base. bites me in the a$$ every time.
 
orangejuiced86;25638 said:
Does activating base reduce the risk of mottling with lighter mettalics?
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There is nothing better of making a metallic spray good, then an ISO>
 
Jimc You should have used the acrylic enamel hardener in your base and let it dry over night at above 55-60* and then put on your clear. I've had this happen also on enamel if I didn't let it dry good before clearing. I just let it set in the sun a few days and it seemed ok.
 
By window I'am guessing you are talking about recoat time. Just give it a little more time between coats and if a real high metalic color I wait overnight to clear coat. I've had colors like a bright sliver get mottling if I clear coat to soon. I'am not a production shop so its no big deal.
 
KevinH;27271 said:
So by putting an activator in the base what does it do to a window?
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Most company's say it extends the time and it really does, yes it makes the base stronger but you are not using enough ISO's and there is not enough Polyols in the base to totally lock down.
When you see a wet on wet system, they usually do this by increasing the ISO (NCO) rate.
 
Jim C said:
i catalyze everything. all my base for prob 8 years now. i had some cheap job recently on some bs part so i had some black limco base which is an acrylic enamel basecoat. boy i'll never do that again. the cat actually half kicks the limco so anything you put over it wrinkles it like a sob. with that said it my fault for not using a good base. bites me in the a$$ every time.
Click to expand...
We used some Limco black base a year ago, on an all over 80K resto to "save money"!?!?!? It was not catalyzed and we sprayed DC5335 on top. There was some delam issues. Was it because of enamel base? Limco says to put their "urethane" clear on top.
 
Not to hijack the thread, but is the same 1-2 ounces of UC activator ok to use in Pro-Spray Metallic ? thanks
 
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