Would one of you guys tell me the different uses or applications for Zinc Chromate, Alodine, Acf-50, and Alumiprep.
Thanks.
Coatings
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wrenchturner
- Rank 4
- Posts: 231
- Joined: Mon Apr 11, 2005 5:05 pm
You can use them all together. Basically, Alumiprep is used to deep-clean the aluminum. Alodine is applied after, to prevent corrosion. Zinc-chromate is the primer which also helps to prevent corrosion. ACF-50 is sprayed on after, usually in the wings or belly, again used as a corrosion preventative. ACF-50 can also be used as a alternative to WD-40 or LPS-1. I'm not sure if that's a recommended use, but I have seen it used lots of times like that. Hopefully tha helps you.
Thanks wrenchturner, I wasn't sure I was maybe overkilling the things I'm working on.
One more question what kind of paint would be best to use on top of the Zinc Chromate, and for engine application would some of these high temperature engine paints like you can buy at CTC be good enough?
One more question what kind of paint would be best to use on top of the Zinc Chromate, and for engine application would some of these high temperature engine paints like you can buy at CTC be good enough?
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GA MX Trainer Dude
- Rank 3
- Posts: 153
- Joined: Wed Aug 03, 2005 4:36 pm
- Location: West Coast
Grouchy
What are you painting - there are so many different paint systems out there to work with. Just a couple of hints and tips from doing lots of painting - aircraft - cars - and f##king houses too.
First off - real Zinc Chromate paint is just about impossible to get any more - part of the enviromental cleanup BS. The spray can replacements range from sh#t to almost acceptable but most no longer have any sacrificial effect for corrosion protection. They will work OK if you are not in a very corrosive environment.
The best and only thing that I will use on aluminium is the 2 part epoxy primers - and follow the instructions to the letter. Proper metal preperation is very important and after the chemical wash is completed keep washing it for at least 2 more washes than you think it needs. If you don't want paint blistering around the seams and river heads this is very important.
Remember when you are priming for a topcoat of paint that the paint and primer must be compatible - best to use the complete system if you can - buy primer and paint from someone who knows what they are doing - CTC is fine for an old bicycle but I would never use their paint on and aircraft - yes people do - and thats OK to - just not what I would do.
The primer actually has more work to do than the topcoat - the primer coating must adhere to the surface and then the topcoat must adhere to the primer. If the primer cannot "KEY" to the substrate then it will lift at the substrate/primer interface. If the topcoat cannot adhere to the primer then it will lift at the topcoat/primer interface. In addition one of the things that many people do not consider when choosing paint and why a paint system is often better is the amount of movement with temperature change - this can be a real problem in high altitude aircraft as they will go from a +40 C runway to -50 C at altitude. If you have differing thermal expansion rates between the primer and your topcoat you are going to have problems.
If all you want to do is prime for corrosion protection - use one of the 2 part epoxy primers.
Last Point!! Use your safety equipment - some of the paints are very toxic and require a full suit and air fed breathing masks. Trying to do it half-ass#d will get you killed or at the least add to your toxic substances burden. I have been away from painting with the old style 2 part poly paints - Endura - Imron etc. but for several years I could walk past a paint shop and tell you what they were painting with just by what it would do to my sinuses. When these paints first came out - early 70's - many of us didn't follow the safety requirements and some have paid very dearly for that.
Hope this helps. PM me if you want more info.
What are you painting - there are so many different paint systems out there to work with. Just a couple of hints and tips from doing lots of painting - aircraft - cars - and f##king houses too.
First off - real Zinc Chromate paint is just about impossible to get any more - part of the enviromental cleanup BS. The spray can replacements range from sh#t to almost acceptable but most no longer have any sacrificial effect for corrosion protection. They will work OK if you are not in a very corrosive environment.
The best and only thing that I will use on aluminium is the 2 part epoxy primers - and follow the instructions to the letter. Proper metal preperation is very important and after the chemical wash is completed keep washing it for at least 2 more washes than you think it needs. If you don't want paint blistering around the seams and river heads this is very important.
Remember when you are priming for a topcoat of paint that the paint and primer must be compatible - best to use the complete system if you can - buy primer and paint from someone who knows what they are doing - CTC is fine for an old bicycle but I would never use their paint on and aircraft - yes people do - and thats OK to - just not what I would do.
The primer actually has more work to do than the topcoat - the primer coating must adhere to the surface and then the topcoat must adhere to the primer. If the primer cannot "KEY" to the substrate then it will lift at the substrate/primer interface. If the topcoat cannot adhere to the primer then it will lift at the topcoat/primer interface. In addition one of the things that many people do not consider when choosing paint and why a paint system is often better is the amount of movement with temperature change - this can be a real problem in high altitude aircraft as they will go from a +40 C runway to -50 C at altitude. If you have differing thermal expansion rates between the primer and your topcoat you are going to have problems.
If all you want to do is prime for corrosion protection - use one of the 2 part epoxy primers.
Last Point!! Use your safety equipment - some of the paints are very toxic and require a full suit and air fed breathing masks. Trying to do it half-ass#d will get you killed or at the least add to your toxic substances burden. I have been away from painting with the old style 2 part poly paints - Endura - Imron etc. but for several years I could walk past a paint shop and tell you what they were painting with just by what it would do to my sinuses. When these paints first came out - early 70's - many of us didn't follow the safety requirements and some have paid very dearly for that.
Hope this helps. PM me if you want more info.
You can train a monkey to ride a bicycle but you can't train it to fix it!!!
Putting a little scuff on a surface with scotchbrite before priming and painting is often overlooked. The two part primers like endura etc.. will really stick if they can get a mechanical grip. Just out of curiosity a year ago I took excess primer and top coat paint left over from small jobs and after quickly wiping off the rusty oily pitted inside surface of some steel drip pans about 20 years old with an alcohol soaked rag,poured on the waste paint and sloshed it around.It stuck like glue and has not come off since, not even a little bit. Any place that fish-eyes formed from oil and grease I just stirred vigourously with an acid brush until it covered.Is this the way to do it?? Hell no! but it does show that a lot of the adhesion of paint must occur due to gripping irregularities in the surface as these surfaces should have had all the paint peeled off due to surface contamination.I have also seen paint flake off in sheets where a pretty good effort was made to do everything right by the numbers, especially when the aluminum is mirror smooth.
Thanks for the replies. I'm just cleaning up the baffles on a C85 and since I have them off I was thinking about painting them white to give the engine a nice clean look. Also since they are off I might paint the cylinders if I can find out how to do it properly without taking them off.
Coatings
My two cents worth.
If you want to do a real nice job, use all the steps you listed. Start with Alumiprep, then Alodine, then a two part epoxy primer, then top coat. Areas such as inside wings and fuselages I would spray down with ACF-50, which I found to be awesome at keeping corrosion at bay. Of course if you are on the prairies, then corrosion isn't a big problem.
But i would reconsider painting engine baffles. Heat and the chemicals in these products don't really get along very well and you will wind up with burnt and peeling paint, I can almost guarantee. As well, the original idea in baffling and firewalls is to control heat, which is beat done with bare stainless steel and aluminum. My preference is to clean the metal up really nice, whether it is stainless or aluminum, so that it is a clean dull finish. Any steel parts I usually prime and paint with high heat engine mount paint to keep from rusting.
Again, this is my two cents worth.
Have fun
If you want to do a real nice job, use all the steps you listed. Start with Alumiprep, then Alodine, then a two part epoxy primer, then top coat. Areas such as inside wings and fuselages I would spray down with ACF-50, which I found to be awesome at keeping corrosion at bay. Of course if you are on the prairies, then corrosion isn't a big problem.
But i would reconsider painting engine baffles. Heat and the chemicals in these products don't really get along very well and you will wind up with burnt and peeling paint, I can almost guarantee. As well, the original idea in baffling and firewalls is to control heat, which is beat done with bare stainless steel and aluminum. My preference is to clean the metal up really nice, whether it is stainless or aluminum, so that it is a clean dull finish. Any steel parts I usually prime and paint with high heat engine mount paint to keep from rusting.
Again, this is my two cents worth.
Have fun
I imagine the c85 baffles have been painted long ago now, but.. the majority of piston engine baffles are essentially ducts to control cooling airflow a relatively low temp application. If it strikes your fancy to improve their appearance and preserve their life by coating them with paint,why not? I like a light colour it shows up leaks and corrosion by-products better plus oil and dirt also clean off a painted surface better than bare metal or at least with less effort. Heat shields/baffles placed near exhaust and turbocharger (high temp)are probably best left natural metal finish to function best.
