Dye back

C

cjetmech

I hope this is the right spot to ask this question. I hear alot of people mentioning dye back, what is this? And why does it happen? A pic would be great if anyone has one. Thanks for answering my newb questions I appreciate it.
 
Great question!
Of course the answer really depends on the product and brand.
Some clears do not like being reduced and that can cause die-back.
SPI does not care about reducer as long as a good grade, low grades can and will kill the clear.
Some clears can cause their own die-back if flash times are not long enough because of the low amount of solids. Not the SPI.
SPI clears can die-back from the following:
Abuse of polar accelerator.
Using a crap reducer.
Baking to hot or to long.
Leaving the booth fan running to long.

Now the above should give you a general idea to why and the differences in clears.

Now the truth, of all the calls I get for die-back, it is 99% of the time, from the base coat solvents.
 
So on these base coats that say max flash times of 2 hours or 4 hours, is there really any harm in waiting overnight to clear?
 
Thanks Barry, that covers why it happens. So die back refers to a loss of gloss in a clearcoat from the reasons you listed?
 
Yes its basically a reduction of gloss from solvents comming out of a cured paint film. This causes the paint to shrink. Low grade reducers usually have a high moisture content which is a gloss killer. The moisture speeds up the kick off on the clear not allowing enough time for solvents to come out including the moisture.
 
AAE;5490 said:
Usually, you can hit it with a buffer and the shine comes back.
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You can get the shine back but there always seems to be a slight cloudiness that will always be there-this will be more apparent on dark colors. Slow quality solvents and or the least amount of solvent is always the best.
 
bmenard;5482 said:
So on these base coats that say max flash times of 2 hours or 4 hours, is there really any harm in waiting overnight to clear?
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Most of the bases give a 16 to 24 hour max set time to clear, some of the better bases are now saying indefinite and the SPI bases were that way, as long as the car did not go out of the booth or outside.

Overnight being 8-12 hours, should really never be a problem.
 
Thanks for clearing that up. I learn a ton just by reading everyones posts and any question I've asked has been answered. Even though this isnt the biggest website the people on it seem like absolute experts which makes me confident what they are saying is correct. Better than getting opinions from 1000 different people who just think there experts.
 
Ahh, thats what happened to my van, but it seemed to appear about a month after painting/buffing (pro spray base, euro)
 
can happen in the first 24 or it can be slowly over months. really the biggest cause i found is not letting the base sit long enough before clear. in an ideal world overnight to 24 hours is best.
 
Jim C;5507 said:
can happen in the first 24 or it can be slowly over months. really the biggest cause i found is not letting the base sit long enough before clear. in an ideal world overnight to 24 hours is best.
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Right as always bro!!


C10.. Ive done this before rushing base.. I remember using omni base one time, and needed allot of coats for coverage.. I mean allot.. Like 7.. I waited about an hour, then shot 3 coats of universal over it..sanded and buffed, it looked great.... the next summer it died back in the summer sun as the solvents escaped.. I sanded with P1200 3m disk and re buffed.. Never died again.. That was my rookie mistake.. Never again!!!

As already stated.... Dont use cheap reducers or cheap bases.. If you do, let them set for extended periods before you clear..
 
Another note also, of the calls I get for die-back 99% are over Dark Green, Dark Blue or Black, all you slowest drying colors.
 
Well this was Gm Storm Grey (ProSpray) and the base sat overnight before I cleared....with 2 coats of Euro unreduced
 
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