Orange peel

[grady]

Was wondering what the causes and solutions to this most undesirable condition. I recently sprayed awl grip's awlcraft 2000 2-part topside paint, the final product was very nice except it had some slight orange peel.

The hull was faired then sealed with 545 epoxy primer, then sanded with 320 and touched up. Then reprimed with another coat of 545 epoxy primer.

the hull was resanded with 320, wiped down and tacked.

The spray reduction was 2:1:3/4 which is exactly what awlgrip recommends.

Temps was low 70,s during application but fell to mid to low 60's 3 hrs after spraying. ( 35% H )

A call to awlgrip suggests that that mix may not have had enough thinners in it to allow it to flow to a smooth glossly finish.

I am about to resand and respray. but would like to be done at that point any thoughts

[mongo75]

I was kinda thinking along the lines of what they said- it seems like your topcoat might have dried too quickly. You may consider thinning it a hair, and turning the air pressure up a little to get a lower volume of paint out of the gun. I would definitely get some more opinions though.

[lazeyjack]

you are doing one of two things wrong
First you need to thin that and mosty linear urethanes up to 60%, that is not a joke! Second you need enough air pressure to break up the paint (atomise) which means no drop off is pressure, so if you a re using a good gun with a big air cap and a pressure pot your rig needs 23 cu ft a min, thats a lot of air
three double header coats, or 2 will do, with around 20 mins between coats, you may be going into cool weatehr, so you can use a speed drying agent too
cheers Stu

[grady]

The awlgrip rep did say that he wouldn't hesitate to thin up to 40%, the mix I used was about 25%.

I am using the 3 coat method with the last coat the heaviest, and I am also using a 2 qt pot. (HVLP) though w/reg at comp set @ 45 #, reg at h2o/oil/mist separators set @ 35 # press in pot set @ 7 #. This set-up is supposed to only use 7-9 cfm. ( And it better cause that's all I got ).

I also thought I may have under atomized, Tricky trying to dial every thing in, with almost all of it being new, I have no base line application experience to guide me.

But the primer laid down well, so did the first attempt with the topside lp.
very happy overall, just finish sanding the beast. 7 hours ( WHEW ) clean up in the morning and spray in the afternoon.

This time I'll add more like 33-40% reducer I'm really afraid to go to far outside of awlgrip's recommendations. But will try to crank up the air feed at the base of the gun to get a finer mist. As far as the material feed goes when I setting it up @ 7 # from the pot at no press @ the tip my paint stream is about 8-10 inches in length before it drops off. ????????

Whatever that means?

Anyway thanks for the replies, I'll be less anxious this time and I'll spend more time on sample spray patterns before hitting the hull.

P.S. I have been mixing all the paint for all three coat at the same time. Should I be doing that. ( it was less than 2 qts [ approx 60 oz's ])

Thanks again

and I will be checking this all night and morning up till go time.


Grady

[lazeyjack]

yes mix all the paint and dont be afraid to go 50%, get your gun up close, move about 20 inches per stroke, you cant over pressure, I use about 100psi , trouble is the air will fill with mist and it gets very hard to see, whatever you do dont breathe this stuff, its deadly and you need outside air supply , carbon filters do not remove the isocyanates
painting has ruined my health for sure, I egt very breathless now, and I have never smoked
Paint and weld fumes Boatbuilders are worh about 1000 bucks an hour, but do we get it?

[MichaelG]

Air pressure is a consideration. I have never sprayed what your spraying but have sprayed the top coat clears in automotive. The number one reason for orange peel is air pressure to high. You just have to test your self on a small panel to you get the finsh result you like.

[the1much]

you need to use cold cure with those mild temps. awl-grip should never be thinned more then 50%, and along with pressure in your gun, look for dampness too, and the right size tip. and before spraying,, put some thinner in your cup and watch the pressure @ your compressor,, and i usually set my pressure @ 80 till my last regulator @ the gun then i play with that till right,, i couldnt say what pressure i havent seen that dial in over 10 years heh

[lazeyjack]

I sprayed Nimbus, exactly as I said, mirror finish , 8 years in boiling sun
60% thinners 100psi at compresser running two guns, 3 coats 20 mins , light first, second heavier , 3rd heavier,

[grady]

I guess the first thing I'll do is reset the reg @ the compresser, then introduce more pressure at the tip.

And of course add more reducers.

Thanks for all the comments

I was doing my test patterns on sheets of cardboard, but I'm going to find a more suitable surface. and test test test!!!!!!!!!!!!!


thanks



Grady

[Kaptin-Jer]

Roll and Tip - Roll and Tip. You guys have got to learn! Safer, less ECO problems, just as fast, and the same bright finish. And I don't have to give my daughter to 1much to do the spraying (if I had one).

[CharlieCobra]

When I sprayed Alumigrip (Aircraft version of Awlgrip) viscosity was the biggest contributor to orange peel. The mfg recommended 17-21 but I found that spraying at 15 with a medium tack coat followed by one wet flow coat was perfect. Folks couldn't believe it was a Polyester Urethane. It looked like hand rubbed lacquer. My gun pressure was 35 PSI.

[grady]

yeah it seems to be the most common answer so I'll certainly add more reducer. I'm leaning toward 40% but I think that will about as high as I'll go.

I don't have anything to measure viscosity. but I am on the fast track to smoothing things out .

Thanks



Grady

[MichaelG]

Another facter in orange peel is having the gun to close to the project. High or low air pressure will be compensated by having the spray gun to far away or to close to the project. (Remember with orange peel, what your looking at is the material being pushed way from itself causing low spots in the finish.) Try to stay near the manufacurers recommendations for thinning and air pressure. ( I always sprayed thinner though). Another helpful hint is having your head in a position where you can see the finish as it's going on the project. Catching the backlighting over your shoulder and seeing the light reflect in your material at the point it hits the project is important. Have plenty of backlighting. (Have you ever seen the inside of a paint booth? there all lights.)
Hope that helps
MichaelG

[Kaptin-Jer]

I don't spray Awl Grip, but I do know that if I rub too hard with a new Tack Rag, or work Awl Grip when the humidity is very high I also get Orange peel. Your problem might be just that simple, but I would bet on the reducer, too much accelerator also causes orange peel.

[the1much]

i just found my awl-grip book thingy,,, says these are the reasons for orange peel
1.hot surface
2. improper gun adjustment or spray techniques
3.improper air pressure
4.orange peel in primer printing through
5.temp. to high or low
6.viscosity is too high
7.wrong choice of reducer
8.improper spraying sequences
9.improper re-coat time
im not saying any of these apply to you, its just what they have in their book