D

Dean

Active Member
I primed my emmpanage parts for the first time. I took the following steps. Cleaned with Dawn soap, rinsed. Metal prepped with 79, rinsed. Alodined, rinsed then let dry for 24 hrs. Primed with Akzo primer 50:50 mix, no thinner.
I used a Wagner HLVP gun with my air compressor. Gun was set at 10psi.
What causes the orange peel like appearance? There are spots where there is no primer coverage. These spots act as if there was something interfering with the adhesion and not letting the epoxy evenly coat the aluminum.I noticed this during spraying. It didn't matter whether I held the gun near (<4") or far (>8"). I also adjusted the primer flow and air flow to no avail.
Should I scrub and rinse the parts again after I rinsed them and let them dry after the alodine step. Should I cut the Akzo primer with thinner? If so what should I use to cut the primer? How much do I use to cut the primer?
It takes 15-20mins for the Akzo to dry. Do I need to clean the gun every time or can I wait 20 minutes then make another batch and shoot it? Thanks in advance for your help. Dean
 
Dean said:
>I primed my emmpanage parts for the first time. I took the following steps. Cleaned with Dawn soap, rinsed. Metal prepped with 79, rinsed. Alodined, rinsed then let dry for 24 hrs. Primed with Akzo primer 50:50 mix, no thinner.
I used a Wagner HLVP gun with my air compressor. Gun was set at 10psi.
What causes the orange peel like appearance?

You have to much paint or to little air. Turn air up or paint down or both.


>There are spots where there is no primer coverage. These spots act as if there was something interfering with the adhesion and not letting the epoxy evenly coat the aluminum.I noticed this during spraying. It didn't matter whether I held the gun near (<4") or far (>8"). I also adjusted the primer flow and air flow to no avail.


If I'm thinking right you have some surface contamination (sp). Right before you prime wipe your parts with MEK or Acetone. The contamination could be just the oils off your hands.


>Should I scrub and rinse the parts again after I rinsed them and let them dry after the alodine step.

Don't scrub after the alodine step. You'll scrub the alodine off.


>Should I cut the Akzo primer with thinner? If so what should I use to cut the primer? How much do I use to cut the primer?

I don't know what primer you are using but the Akzo primer I use I don't thin.


>It takes 15-20mins for the Akzo to dry. Do I need to clean the gun every time or can I wait 20 minutes then make another batch and shoot it? Thanks in advance for your help. Dean
Click to expand...

Again not sure of your exact primer but primer dries quickly after it has been sprayed but the pot life should be 2-4 hours. In the winter mixed primer will stay in liquid form in a cup over night. It should be OK to leave primer in your gun for 20 minutes.

Hope this helps


:)
 
a clean air line is essential. I had some of that orange peel stuff you describe, and after using a dedicated hose, with a GOOD air filter, it was gone. moisture and oil etc.. in the air line can cause that problem.

do you have a good air filter? you sure you don't have any oil in the line (oiling that air drill?).
 
I'm not familiar with the gun you're using, but 10 psi could be way too low depending on where it's measured. Usually around 10 psi at the aircap is good, but unfortunately most gauges measure pressure at the gun inlet. This is usually MUCH higher. For instance, I use a SATA hvlp for most things and run the inlet pressure at around 20 psi. to get an aircap pressure of 10 psi. Next time you use the gun, spray it at some blank board or something and take note of the spray pattern. AKZO is a good consistency for spraying without any thinner, so you should get a nice fan pattern with tiny little particles. If you see large droplets on your test spray, the pressure is too low.

Also, this stuff needs a REAL thorough stirring before and after you add the catalyst. I usually let it sit for about fifteen minutes after I add the catalyst, and then come back and give it a good stir before spraying.

Regarding contamination, anything oily is bad. Water is real bad too. Make sure you have some sort of water separator on your air line and you should also get some of the little plastic screw on filters that go right on the gun. They catch a lot of water that makes it past the water separator.

Steve Zicree
RV4 WIRES!!!
 
I have 40psi at the tank regulator and the gun has its own regulator. I dialed it to 10 psi at the gun. I will check my lines for oil and water. I do not currently have a water separator on the air line so maybe water was getting into the primer and causing the spots. I don't have an oiler on the line. I will try a higher pressure but the problem appeared to be that the primer would not adhere to small spots on the metal no matter how thick I shot it. I used 60ml syringes to measure and mix the Akzo. Maybe there was leftover silicon on the syringe from manufacture and this caused the spots.
Just so I'm clear, are you saying that I can mix the primer, wait 15 mins and then shoot it. Won't it dry in the meantime and set up. It seems to set very quickly once applied. It is also difficult to remove. Acetone works but doesn't seem to be the best chemical. Any suggestions on cleanup?
Thanks everyone for your response. Dean
 
The 15 mentioned is called induction time. You need a few minutes for all the primer molicules to get together with the catalyst molicules and say Hi :D

You might try this. Take the regulator off your spray gun and store it nicely away in your tool box. Turn the air on your compresser up to 100. Most HVLP guns reduce air pressure by a factor of 10:1. My big HVLP setup at work reduces at 7:1. I run 85 - 90 psi at the wall. With the pressure drop due to the length of my air hose I'm right where I need to be at the air cap.

:)
 
Dean said:
Just so I'm clear, are you saying that I can mix the primer, wait 15 mins and then shoot it. Won't it dry in the meantime and set up. It seems to set very quickly once applied. It is also difficult to remove. Acetone works but doesn't seem to be the best chemical. Any suggestions on cleanup?
Thanks everyone for your response. Dean
Click to expand...

Dean,

Assuming you're using the AKZO primer that Spruce sells, you need to wait more like 30 minutes for the induction time, and it has a pot life of 8 hours. I've used the stuff over the course of a whole day of priming and never had it dry in the gun.

You really need to read the datasheet at http://www.akzonobelaerospace.com/products/DataSheets/463-12-8.pdf
Lots of good info.

For cleaning the gun I use acetone. If you're trying to clean primer that has set on something you can use MEK and a lot of elbow grease and it'll eventually come off.

PJ
40032
 
Back to the air pressure thing. If the gauge on your gun is right near the air inlet it's just measuring line pressure. Actually you can forget all the talk about psi and just adjust the pressure upward until the spray pattern starts to become a big ol' foggy blast and then back it down a bit.

It was suggested on here that you could run it at 85 psi and that the gun would drop it down. I think someone is confused. If you try to put anywhere near that much pressure into a gun that was designed as HVLP you'll waste more paint than a conventional gun. These things usually require line pressures around 20 psi. with the trigger held open.

Don't worry about the akzo drying while you're working. Once sprayed into a thin film it dries super quick, but takes much longer in a gun. It cleans up very well with acetone unless it has cured.

Good Luck,
Steve Zicree
 
On boy; lot's of places for things to go wrong, so let's touch on a few:

I primed my emmpanage parts for the first time. I took the following steps. Cleaned with Dawn soap, rinsed. Metal prepped with 79, rinsed. Alodined, rinsed then let dry for 24 hrs.

Don't use soap at all. Use a generic "wax and grease remover" (eg., Ditzlers part number is DX330, and Dupont's is called "Prep Sol") because soap will never clean off contaminants as well as a wax and grease remover. Not only that, it's possible to leave soap residue on the surface which won't help a bit.
Additionally, you wipe on wax and grease remover WET and then DRY it immediately with a fresh, clean, towel. Don't allow it to evaporate on it's own because any contaminants floated with the wet application will simply stay on the surface.

Primed with Akzo primer 50:50 mix, no thinner.

I don't really care about ratio of the mix other than that you DO IT LIKE THE INSTRUCTIONS SAY with regard to the ratio of primer to catalyst. However, I would also thin (with a compatible thinner/reducer) the primer by about 50% no matter what the instructions say.
First of all, the inert thinner won't affect the chemical reaction of the primer other than to slow down the chemistry. It will still, however, cure as intended.
Second, you're priming a brand new aluminum surface so you don't need very much filling as much as you simply need the adhesion promoting and corrosion protection properties of the primer.
Third, thinning the primer a bit will encourage it to lay down REALLY WELL, and all you should have to do before going into the color coat is to scuff it to get rid of any dust nibs.

I used a Wagner HLVP gun with my air compressor. Gun was set at 10psi.
What causes the orange peel like appearance?

Lot's of things can cause orange peel so it's hard to say in your case. However, some things that cause it are:
1. Improper pressure for atomization.
2. Improper viscosity of the material. This is sort of related to #1, but don't think that just cranking up the pressure will overcome an improper viscosity mix.
3. Wrong size needle and fluid nozzle (they're matched sets) for the material being sprayed. (This a common one among people new to painting).
4. Some surface contamination that prevents the material from "wetting out".
5. Using the wrong thinner/reducer for the ambient temperature.
You could be having a problem with more than one of the above.

There are spots where there is no primer coverage. These spots act as if there was something interfering with the adhesion and not letting the epoxy evenly coat the aluminum.I noticed this during spraying. It didn't matter whether I held the gun near (<4") or far (>8"). I also adjusted the primer flow and air flow to no avail.

Do those spots look like little "craters" if you view them from an angle? If so, they are typically called "fish eyes" and are caused by some kind of contamination on the surface.
Or are you talking about striped areas with very little coverage? If that's the case, you can add improper fan adjustment to the list of things above that can go wrong (and oh yea, I'm just hitting the high points... there's lots more where they came from :eek: )
You might even be seeing some kind of reaction to some soap residue that may not have been totally rinsed from the surface.

Should I scrub and rinse the parts again after I rinsed them and let them dry after the alodine step. Should I cut the Akzo primer with thinner? If so what should I use to cut the primer? How much do I use to cut the primer?

Yes, after the Alodine has been allowed to react with the aluminum, you need to rinse it off with water and the blow it dry with clean air.
Then before you prime it, wipe it wet with wax and grease remover, wipe it dry with a clean cloth, give it a gentle wipe with a tack cloth to remove any dust, and spray the primer.
Note that many companies recommend using either RO water (filtered by Reverse Osmosis) or Distilled water because it is VERY possible that your local water may have a high enough mineral content as to interfere with the Alodine chemistry.

It takes 15-20mins for the Akzo to dry. Do I need to clean the gun every time or can I wait 20 minutes then make another batch and shoot it? Thanks in advance for your help. Dean

I haven't used the Akso products myself, but I'm sure it's like any of the other brands in general use. So my first question is; what does the P-Bulletin say about "pot life"? I'd be surprised if it's any less than at least 8 hours which would mean that you could mix up a batch and let it sit in the gun and use it all day until you hang it up for the night at which time you'd clean the gun and have a beer.

Like I said, there's lot's of places where things can go wrong in the paint "system". And being a system, anything that goes wrong anywhere in the system will affect the whole system.
I'm guessing you didn't want to hear that. :eek:

As far as the parts you've already sprayed, I'm afraid what you really need to do is to strip off everything down to the bare aluminum and start all over.
 
Last edited:
Thanks for the information. I definitely have craters all over the entire piece(s) and they are all uniform. It appears I have some type of contamination problem. I will rinse with demin water and then clean with grease remover after I alodine the pieces. I will use rubber gloves when handling the parts. I will also let the primer sit for 30mins (induction time) before shooting it. Last time I mixed and shot immediately. Thanks again for all your help. Dean
 
szicree said:
Back to the air pressure thing. If the gauge on your gun is right near the air inlet it's just measuring line pressure. Actually you can forget all the talk about psi and just adjust the pressure upward until the spray pattern starts to become a big ol' foggy blast and then back it down a bit.

It was suggested on here that you could run it at 85 psi and that the gun would drop it down. I think someone is confused. If you try to put anywhere near that much pressure into a gun that was designed as HVLP you'll waste more paint than a conventional gun. These things usually require line pressures around 20 psi. with the trigger held open.

Don't worry about the akzo drying while you're working. Once sprayed into a thin film it dries super quick, but takes much longer in a gun. It cleans up very well with acetone unless it has cured.

Good Luck,
Steve Zicree
Click to expand...


Sorry, not confused. That is how it is. It set my supply pressures according to the tables in the spray guns manual.

:)
 
Dean,

FWIW, this is what I do on internal parts, it works like a champ. Scuff the parts with scotchbrite until there is no shine, clean with MEK turning rag frequently (it will go black quickly). Mix the Akzo, exactly 50:50 isn't critical, I use a stainless soup ladel that takes a couple of oz, three to six of green stuff then same of clear stuff. The green stuff has to be stirred up very well (and settles out in two or three weeks). Stirr the Akzo well and leave for 30 mins. Once parts have been scuffed don't touch with bare hands - wear rubber gloves. I use a cheap "HVLP" gun from Harbor freight, it takes 40 psi at the gun (BTW its not really HVLP). To spray the stuff I use a tack or dust coat first, don't be in too much of a hurry to get too much paint on too quickly. Wait a minute or two and put a full coat on. If required sometimes I put a 2nd coat on. I find the Akzo remains sprayable for a day or so (in 80 or 90* temps). Must clean the gun the day you spray otherwise its very difficult. I use regular thinner or MEK for cleaning. I always miss bits here & there, can be covered up using a small brush (this is the inside - no points for beauty). If I want to alodine something first I use a "Touch'n'prep" pen, much easier than regular alodine.

I use a regular filter mask when mixing and a Hobby air respirator when spraying - otherwise I get a horrible headache.

I have not experienced the problems you are seeing. The main problem I get occasionally is poor flow out of the paint with a kind of dusty surface (that I can rub off easily with scothbrite) - but usually everything is just fine. I think this is because my gun is flowing not enough paint or too much air. I've tried thinning with regular thinners (say 10 or 20%), but that doesn't seem to make much difference. Overall I'm very happy with the Akzo paint - seems fairly tolerant of poor technique. As others have said, I suspect you have dirty parts or oil/water in your air line.

Hope this helps, Pete
 
Don't dial down the air to 10 psi at the gun. The 10 psi is at the tip. I had trouble too until I read a couple of good online articles.

Here
http://hotrodders.com/kb/body-exterior/articles/spraygun.html

and this one here was very good
http://purplesagetradingpost.com/sumner/techinfo/HVLPspraygun.html


I followed the latter's advice and got beautiful results. Now, no offense intended, but for some stupid reason, even though I finally had the gun set perfectly, I read a message here about opening eveyrthing wide open and backing off -- or some such advice. Don't do it. I tried it. Major disappointment and I was stupid to try when I had finally gotten it calibrated perfectly. But I figured if it was posted here, it must be right. :eek:
 
An excellent way to check for surface contamination before priming is checking for a "water break free" surface. To check for this, dip into or spray the part with water. The water should form a continuous film (water break free) without beading up for over 30 seconds. If there is a contaminated spot, the surface tension will cause the water to pull away from the surface leaving a dry spot with no water film. This area needs more cleaning. A good time to check is when rinsing off the alumiprep if you are etching. Since doing this, I have not had any problems with fisheyes. Other than that, the AZKO is a very easy primer to work with.
 
You must log in or register to reply here.