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Working with epoxy primers

G

GPV

Member
Hi All,

I would like to try priming my 14 with an epoxy based primer. The instructions for the products I have been looking at suggest that whole cans of part A and part B need to be mixed and there is no way to use partial cans over multiple priming sessions. This is apparently due to the hardener degrading over time. This is obviously very inconvenient and the only way to avoid excessive waste would be to do huge batch priming jobs and use a whole can at once. I would prefer to prime in reasonably small batches and mix the primer each time.

Does anyone have experience with using partial cans successfully?

Many thanks,

Greg
 
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Absolutely, just mix what you need. Seal them back up in the cans and mix well before using the next time.
I use a couple stainless dippers for each part since Akzo is 1:1. Just dip out what I need.
 
Eastwood

I used the Eastwood primers on my build. Good price and durable surface. You can dip out whatever amount you need. I would recommend ordering some urethane reducer with it. The unused part will thicken before you have used it all.
 
You can get a few years out of epoxy primer so long as you make sure the lid seals well and it doesn't get too hot or too cold.

A stir stick that's touched hardener (Part B usually) should never go in the Part A can (and vice versa)!

I punch 6-8 holes in the bottom of the rim of the can to help with drainback.

I've tried various ways to dispense. None of them work particularly well. For large amounts I've used a plastic spout that snaps into the rim. Works ok except cleanup of the spout is annoying and eventually the o-ring fails because I'm too lazy to clean it properly. For smaller amounts I use the cheapest ladle I could buy. It doles out about 75ml at a time.

I've heard good things about the Mixing Mate but have never used it.

DeKups or PPS 2.0 disposable cups are well worth the cost. I prefer the PPS 2.0 since it has built-in graduations on the cup holder. The DeKups and PPS 1.0 use an insert.

Speaking of Eastwood, I've been using their Concours gun to spray primer and it works well. It's quite a bit better than the cheap purple guns I've used in the past.
 
A lot of builders use Akzo epoxy primer, including myself. It works really well and it?s tough stuff after it?s hardened. I use stainless ladels into a Pyrex measuring cup. Then mix the two parts. Don?t forget to get some filters and pour through the filter into the gun cup. I use the el cheapo Harbor Freight spray gun for primer and it works fine.
 
Mixing Mate

I highly recommend buying the "Mixing Mate". It is worth every penny since it replaces the lid, stirs the material and allows for precise pouring of the desired quantity. When done I simply put it on the shelf until the next use and keep the mixing mate on the can until the entire can of paint is gone. Then I clean it once and move it to the new can. Wonderful product to have especially since their is little to no wasted material. I don't know about you but I don't like wasting material in paper towels or rags cleaning up drips when this stuff costs hundreds of dollars per gallon.
 
We used the 3M Accuspray system with SEM epoxy primer with good results.

We even setup one batch with a sealer in battleship gray for the cockpit, it's really robust and when you do ding it no flaking off like with paint. It's also very easy to touch up.
 
Syringes

I use syringes. I have rubberless as well but have not seen any problems with either.
Label the syringe and plunger so they don't get mixed up. Zero waste. Easy clean up.
 
Be careful with syringes. Medical ones have silicone grease on the rubber plunger. Caused me some grief with fisheyes until I identified the source.
 
Thanks everyone, lots of good insights and experience there.

I'm trying to avoid AKZO as it's hard to get here, zinc chromate is nasty and it's not the cheapest stuff. Hopefully the cheap zinc phosphate primers I am planning on using work sufficiently well. Got to be better than a rattle can at least right?

There are some chromate based primers available here made by a company called axalta, but they all seem to require alodining first. Not too keen to deal with that also.

Those mixing mates look great but I am not sure if they fit the litre sized tins we have here (although the size is close to 1qt). Fortunately the Eastwood does come in quarts so if I decide to use it the mixing mate will be a definite option. Otherwise I'll try syringes or small ladels.

Thanks for the help!

Greg
 
GPV said:
Those mixing mates look great but I am not sure if they fit the litre sized tins we have here (although the size is close to 1qt). Fortunately the Eastwood does come in quarts so if I decide to use it the mixing mate will be a definite option. Otherwise I'll try syringes or small ladels.
Click to expand...

Here in the states a quart of paint runs about 1/3-1/2 the cost of a gallon. If you can get gallon-sized (4L? 3.8L?) you should come out ahead.
 
+1

mulde35d said:
I highly recommend buying the "Mixing Mate". It is worth every penny since it replaces the lid, stirs the material and allows for precise pouring of the desired quantity. When done I simply put it on the shelf until the next use and keep the mixing mate on the can until the entire can of paint is gone. Then I clean it once and move it to the new can. Wonderful product to have especially since their is little to no wasted material. I don't know about you but I don't like wasting material in paper towels or rags cleaning up drips when this stuff costs hundreds of dollars per gallon.
Click to expand...

100% agree with this. Ive had a pair of these on my epoxy primer tins for a few years. Works exactly as described above. Highly recommended.
 
GPV said:
Thanks everyone, lots of good insights and experience there.

I'm trying to avoid AKZO as it's hard to get here, zinc chromate is nasty and it's not the cheapest stuff. Hopefully the cheap zinc phosphate primers I am planning on using work sufficiently well. Got to be better than a rattle can at least right?

There are some chromate based primers available here made by a company called axalta, but they all seem to require alodining first. Not too keen to deal with that also.

Those mixing mates look great but I am not sure if they fit the litre sized tins we have here (although the size is close to 1qt). Fortunately the Eastwood does come in quarts so if I decide to use it the mixing mate will be a definite option. Otherwise I'll try syringes or small ladels.

Thanks for the help!

Greg
Click to expand...

Hi Greg.
I see you are in QLD. If you decide on Akzo, Sea Air Land systems distributes Akzo products in Aus. They are in Eagle Farm. I have purchased a few times over the years from them hassle free.
http://www.seairland.com.au/
Cheers
Richard.
 
Akzo here and I use syringes as well. Good note on not using medical ones. Garden variety are cheap on amazon, and I use the rubber plunger ones until they get hard to plunge, then get another one - buy them by the bag full. Also my Akzo is from the start of my build, 5yrs ago, and still have plenty left and it works fine. Keep the lids on as everyone else has said. Sprayed some just a few weeks back with no issues.
 
Rattle can etch primer vs cheap 2k epoxy

I've been deliberating on the rattle can vs 2 pack epoxy based primer decision, and had nearly settled on rattle can until I performed a basic scratch and solvent test over the weekend.

For the test I sprayed some aluminium sheet with cheap 2k zinc phosphate based epoxy primer. The sheet was prepped with scotch brite and cleaned with acetone before spraying.

I already had a piece of similarly prepared sheet sprayed with a popular 1k rattle can zinc phosphate etch primer from a couple of months ago.

The difference in finish is obvious, with the 2k having the appearance of a semi gloss plastic and the etch primer being somewhat "powdery", for want of a better word.

After the 2k job was allowed to cure overnight I tried some scratch and solvent tests. While both products could be scratched with sharp metal implements, the 2k primer was completely resistant to being scratched with sharpened hard plastic. The 1k rattle can primer performed admirably, but was able to be scratched off in big wide strips leaving shiny metal behind. Even with sharp metal, far more pressure was required to completely penetrate the 2k coating.

I also tried rubbing with a couple of solvent (alcohol) soaked rags. The 1k rattle can rubbed off easily while the 2k epoxy was unaffected.

This is obviously far more stress than the coatings would usually be subjected to, but it gives some idea of how they may perform long-term or when wedged between vibrating parts.

All in all, the 2k epoxy seemed to provide a pretty impervious and resilient barrier while the rattle can stuff seemed only temporary.

I had high hopes for the rattle can as it is so convenient, but I reckon if you're going to all the effort of removing that nice alclad then you definitely want something as good as or better than the protection you are removing. I'm not so sure rattle can does that (this brand anyway). So I will be using some form of 2k epoxy primer or not priming at all. Still trying to make that decision!

Of course these are just my thoughts and your mileage and/or specific rattle can primer may vary.
 
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Hey Greg,

I?ve been using the water based Stewart systems EkoPoxy for my build - I?m building at home and it?s environmentally and physically non-toxic. The gun just cleans up with water. I acid etch on the drive and just hose it off. I used syringes to get it out of the pail, which I?ve cleaned with acetone and scotchbrite to remove any silicone.

It?s not that cheap but is hard wearing once it?s cured for a few days. I can dimple after 12 hours.

The only downside is the cost - at least shipping from the us is non DG. The last purchase was 2 quart cans which I mixed together in a plastic pail. Total cost delivered was $308 AUD (paint 200 ish and shipping 100 ish).

I searched high and low for a primer solution here in Aus, but couldn?t come up with anything that was not completely toxic or impossible to clean up.

I did come across a rattle can the other day which I am going to try - it?s called Norglass no rust all surface primer - they answered via email very promptly and advised their primer is not hygroscopic and doesn?t need to be topcoated. So I?m going to try it out and potentially use it for small jobs and on steel (you can?t use the ekopoxy on steel as it flash rusts).

Hopefully this is of some help to you.
 
Interesting,

I just got this back from a manufacturer of zinc phosphate epoxy primers:

"....The zinc phosphate in our AYB Epoxy Primer does not have any benefits for aluminium, only steel...."

So there you have it. Most rattle can primers in Australia are zinc phosphate based, including Wattyl Super Etch.

Given there is no cathodic protection and the coating seems a bit porous, I really do wonder how rattle can etch jobs will hold up long-term.

A non-chromate 2 pack epoxy might be a reasonable compromise as it at least provides robust isolation from the elements. Otherwise, it looks like it's chromate or no primer at all.
 
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Primer options

I started out in mid-90's using a Wattyl eurocryl self-buffering etch primer that was zinc chromate based, but it is no longer available due to health risks (carcinogenic). Recently investigated everything I could locate in Australia; Akzonobel, PPG etc. and anything aerospace related is around $700 per gallon. The Stewart Systems water based primer is around $300-$400 per gallon, I understand it is a bit harder to apply, but works well.
For painting the exterior, I've settled on Nason 2-pack epoxy primer. This will be top-coated and it provides a very tough barrier, but it's a hassle to put on because it is toxic (isocyanates - needs a forced air breathing system) and pot life is limited. That makes it impractical for preparing small parts.

My understanding of single pack etch primers, e.g. Wattyl self-etch, is that they are designed to be over-coated. They are porous, so they don't provide any real protection from corrosion on their own.

I've had good test results with Dulux all surface metal primer. If the aluminium is scuffed with red scotch brite and degreased, it sticks very well. After a week of curing it is very abrasion resistant. Cost is less than $100 for 4 litres. I have decided to use this to prime the inside of the fuselage where there are lapped joints in Alclad 2024, and for all 6061 and anything that is steel.

Alodine would also be an option, but it too is toxic and very time consuming.

I am aiming for an airframe that will last about 20 years. I would rather fly a bit sooner, than over-kill with corrosion proofing.
 
I have found non 2 part primers, ie rattle can primers almost hold up to water. It may be OK for totally sealed parts such as inside flaps etc. if you are priming an area such as cockpit interiors where you will scuff or get mild solvents on you will need epoxy. If you will be doing a bunch of painting get a Hobby Air with a full face mask. Respirators do not protect you from epoxy fumes. Think eyes.

Of course one of my best friends who paints with chromate once or twice a week says he just holds his breath. Sad to see his hands starting to shake.

Bob Grigsby
Cub flying
3B getting close I hope
Dues paid
Too many hoops for pic posting. Luddite syndrome
 
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