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Questions regarding EkoCrylic over EcoPrime, finish defects

Posted: Sunday, June 15, 2014 11:14 PM Quote
Hello,

On Friday (June 12th, 2014) I shot my entire airframe with EkoPrime Smoke Grey primer.  That finish came out well, so on Saturday I did the necessary prep work then shot the tail section and wings (bottom side of one wing, both sides of other wing) with EkoCrylic top coat in Juneau White.  The good news is that there were no runs!  The bad is that there is mild orange peel on the entire topcoat (it improved 24 hours later as the paint flowed out a bit more), and the grey can be seen throughout the finish if you look at it with a close eye.

Here are the details:  I measured the paints by weight as shown in the video (divide weight of paint in grams by 3.3, add that amount in catalyst after zeroing out the tare, zero out the tare again, divide original paint weight by 2.75 then add that amount to the paint/catalyst).  I thought I did that all properly, but after checking the flow rate with a Zahn #2 viscosity cup, I came out to 14 seconds.  Since you suggest 20-21 seconds, I made up more paint-catalyst mixture and added it to the original mixture until I got 20 seconds.

The weather was clear in the mid 70's and low humidity.

The setup I have is a Croix CX-10 turbine with a Sicmo HVLP gun with the container underneath the sprayer (all high quality equipment from the 90's, which I borrowed from a homebuilder).  There is only one control on the sprayer, which I believe is the fan control.  While spraying on Saturday, the fellow who loaned me this unit said that I needed to adjust the airflow control (which is located on the hose) to approximately half the air flow since it is a three-stage turbine that can potentially run two guns at a time.

I would start spraying with a low setting on the gun, then after each pass I would adjust that control a little bit higher.

I did two cross coats--three fog coats and one wet coat.  

Any suggestions as to what I may have done wrong?

As for repainting, what should I do to prep the already painted surface for another coat?  Should I do a fog coat/wet coat, or would one wet coat suffice?  How can I tell the difference between a wet coat and fog coat while I am spraying so I can correct myself?

Finally, as for the surface that is still in primer, since I am returning to work on Monday I may not be able to spray a top coat until next weekend.  Even if I can do it earlier, the weather here is forecast to be in the mid-upper 80's and perhaps in the 90's, which I think might be too hot for spraying.

Thanks in advance for your help.
Posted: Sunday, June 15, 2014 11:39 PM Quote
I highly suggest shooting test panels before ever painting any airplane parts to make sure you have a good process and technique worked out first.  Always test the paint viscosity cup with water first to verify flow rate of 14.5 seconds.

Try a 4:1:1 ratio when mixing paint.  You'll probably like the results better.  

I can not give much help in regards to how to use the spray equipment but I would personally leave the air flow alone and only change how much fluid you're introducing to that airflow.  

Re-painting you would wipe the surface with Isopropyl Alcohol then sand with 320 to get the surface smooth.  Tack rag it and then wipe with alcohol again and wait 15 min before spraying a tack coat/wet coat

Jason