Mysterious Solvent Pop... HELP :(

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PostPosted: Wed Jun 29, 2022 2:12 am
Desperately need your help... Out of clue as well as the 3 painters I spoken with...

First layer of clear: As soon as the flash time ends (approx 12-15min), solvent pops begins Millions of bubbles everywhere...

Really simple to reproduce:
1. Clean and sand the part 500 grit
2. Clean part (I tried everything... even to simple Water with a bit of soap)
3. Ensure part is thoroughly dried before shooting clear
4. Shoot a first layer of clear, if layer is on the thick side, I will see the clear "boiling" (bubbles appearing and disappearing as I look at it). If the layer is real thin I dont see this immediat effect, but in all the case, after flash time solvent pop appears and remains as criters.

What it is not and why:
1. Temperature & humidity: 73F at 55% humidity
2. Air at the gun: Was happening before and even after I added a 3 stage professional filtering (water catch with macro filters, Micro filter, big cylinder of dissecant, pumpink at gun) obviously no apparent numidity going out of gun. Dissecant still blue. All lines are new. No water in compressor.
3. Surface Prep: Tried all possible combination from complex to simple part cleaning protocol and I always let time for the part to dry.
4. Layer thickness: Happens even on real thin layers.... Gun barely open (5 turns closing) from medium to higher pressure(24 to 33 psi), always same issue. Also happen on thicker layer which is almost running.
5. Clear coat brands: Tried all possible speeds of Reducer (fast and slow) of (2) different brands: House of Kolor as well as Nason 468. Always same issue.

I really dont know what is happening... Why is the clear boiling like that and so sensitive??

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PostPosted: Wed Jun 29, 2022 10:55 am
I haven't used those particular products (Nason - one time only) but if you are mixing with proper reducers and activator they should spray out with no issues.

Something isn't right if your are getting solvent pop.
Common causes:
(1) Thinner/reducer evaporating too fast for spraying conditions;
(2) Inadequate flash time between coats;
(3) Excessive film thickness or "piling on" of heavy/wet coats;
(4) Too much air movement causing surface to "skin over" before solvents evaporate;
(5) Excessive purge/flash time before force drying.

Are you wiping the surface down with a solvent based automotive paint Wax and Greaser Remover?
This is generally the last step in cleaning prior to spraying paint or clear and needs to flash off at least 30 minutes depending on temperature.
I like to apply it by using a spray bottle. Spray it on and then before it dries, wipe it off with a clean shop towel. Repeat until the towel comes up clean.
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ACTS 16:31



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PostPosted: Wed Jun 29, 2022 11:09 am
tks!

cleaner: yes with water or water and wax remover (FastClean). waited 1h and even dried with air gun.

air movement: tested with booth fan on and alao fully off... same issue after 15-20min (flash time)... it happens obvuously a bit faster when booth fan on. same if i apply a bit of heat.

flash time: happen even on the first clear layer directly on the prepared part a little after the flaah time when clear starts to rigidify... even tried to pre apply an intercoat and alao happens and did not helped

layer thickness: even with the gun barely open a really minimum thickness this happens..

product and mix ratio: tried two different system and with all their possible reducer speed... same issue... yes following exactly the ratios...



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PostPosted: Wed Jun 29, 2022 11:18 am
not sure its a hint: if i spray a bit tick i literraly see the clear "boil" the 5min following the spray... eventually stops but again 20min after i have the reported solvent pop critera... and in that case of a bit heavy spray the clear stays soft even afte baking IR 140F for 30min (as per spec)



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PostPosted: Wed Jun 29, 2022 4:05 pm
what material os the part youre trying to spray made of? just shooting clear on it or is there a basecoat on it? can ya get some pics uploaded?



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PostPosted: Wed Jun 29, 2022 7:38 pm
Yes, I'm also thinking the clear doesn't like the base coat.

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PostPosted: Wed Jun 29, 2022 7:48 pm
Agree. Need to identify what he's clearing over.

OP, it's important we need exact paint you're using under the clear and details of reducer/thinner that is being used with it.

Pictures would also be a big help.
Chris



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PostPosted: Wed Jun 29, 2022 10:59 pm
What Brand of Clear are you using? and EXACTLY how old is it?
What Brand of Activator are you using? and EXACTLY how old is it?
IS it a Fast or slow activator?
Yes they do Make Fast medium and slow activators. Depends on the manufacture but most all do make different temp/speed activators.

Usually with too fast of activator you get blushing But could also be described as solvent pop. (The millions of bubbles is the clue!) Sounds like too fast of an Activator for the temp sprayed to me OR a Mismatch of Activator and clear.
Or really old clear and fresh activator or vise versa you get the idea.....

Why would you mix it with House of colors reducer and then try Nason reducer?
Never Mix Product brands ever! yes some people do it but its not a good practice.
I myself never reduce clear EVER! Yes some people it. I don't myself as Its designed to be used as is UNLESS the TDS says to do it I use it as is. Even when the TDS says IT can be or may be thinned with Reducer I still never do it. Clear is usually designed to be used as is.

At any rate is sounds like Blushing to me please Post Pictures please
Post sprayed and cured if possible
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PostPosted: Thu Jun 30, 2022 3:15 pm
no i would never mix brand of clear and reducer!

just said i tested 2 systems...HOK usc01 (3:1:1) and then Nason 468 (4:1)... and also tested both their slow and their med and fast reducer. so its not that. both are high solid and brand new gallons. was happening with the previous batches as well. following exactly the ratios of the specs between clear/activator/reducer)


here is the pic:
Image


it looks minor but its all over the place just hard to take pics of it



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PostPosted: Thu Jun 30, 2022 3:32 pm
carbon fiber?
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