Paint Prep - Carbon Fiber Parts

[Daveembry]

This is from the link I gave you to my post. Note it lists that etching primer for aluminum surfaces and is what I have been using.

CC now has confirmed (via Pete below) they are using the DP50LFG for the composites. My info below is exactly what CC and PPG recommend for aluminum, composites and paint with the FDGH Delfleet Evolution paint system. Don’t know what else to say?

Hope that helps. No other conclusions.

Delfleet Evolution Painting

Primers

• Aluminum surfaces. F3960G primer 1:1 with F3961F Catalyst. 1 wet coat. Paint immediately after sanding/cleaning surface. 24 hour pot life. 30 min. – 72 hours before sanding required before topcoat.
• Plastic & Composite Surfaces. DP50LFG Epoxy Primer (the “50” is Gray color) 2:1 with DP402LFQ Catalyst. 72 hour pot life. 1-2 wet coats. Dry to topcoat: 30 minutes if 1 coat and 60 for 2. Sand after 1 week to Recoat/topcoat.
• Plastic Windows. (“D” windows and bottoms of front windows). Same but first spray Bulldog Adhesion Promoter on; let stand 5 minutes and then spray primer.

Topcoat

• FDGH Delfleet Evolution. Mix 3:1 with F3260 Hardener and 6 oz. F3400/F3405/F3410 Accelerator per mixed (after the mix) gallon. F3400/Fast Dry. F3405/Medium Dry. F3410/Slow Dry.
• If hot and humid you can add 10% of the reducer F3331(warm temps); F3330 (medium) and reduce flash time between coats to 5-10 minutes. I found it a little too thick without the reducer coming out of a 1.3 tip, so I did use the reducer.
• 4-5 hour pot life @ 70F. 1 cross coat or 2 coats.
• 1 cross coat or 2 coats with 5-8 minutes between coats if using the faster accelerator. Don't let it get too dry.

Dave, I appreciate all the work you have done to detail your building methods.

I have read through the data sheets extensively, and try to listen to all the experts, you, the guys in the local paint store, and the old painter who just retired 6 months ago. I have spent hours reading the PPG stuff.

In the FDGH data sheet, one statement says "Performance Comment: Wash and Etch primers must be sealed before applying topcoat for optimum performance". The recommended 3960 is an etch primer. I haven't heard any mention of that from you or CC or any of my other experts.

I am feeling some frustration this morning after a disaster yesterday painting my struts. I'm still looking into the cause, but it may be that I didn't seal the primer, there is some incompatibility there. I will try to call PPG when they get to work.

Thanks, John

[Daveembry]

What happened with the struts? All aluminum I have primed and immediately painted with no problems.

Dave, I appreciate all the work you have done to detail your building methods.

I have read through the data sheets extensively, and try to listen to all the experts, you, the guys in the local paint store, and the old painter who just retired 6 months ago. I have spent hours reading the PPG stuff.

In the FDGH data sheet, one statement says "Performance Comment: Wash and Etch primers must be sealed before applying topcoat for optimum performance". The recommended 3960 is an etch primer. I haven't heard any mention of that from you or CC or any of my other experts.

I am feeling some frustration this morning after a disaster yesterday painting my struts. I'm still looking into the cause, but it may be that I didn't seal the primer, there is some incompatibility there. I will try to call PPG when they get to work.

Thanks, John

[aflyer]

What happened with the struts? All aluminum I have primed and immediately painted with no problems.

Short answer is that I prepped the struts with acid etch, alondine, and K36 primer. Then I painted topcoat (just as I did with the gear legs after just scuffing the white powder coat they came with, which came out perfect) and the paint has areas of what looks like very small fish eyes and funny rough areas (not like dry paint, but almost very small blisters).

Yesterday I spent some time on the phone with a PPG commercial coatings tech rep. He couldn't point to any smoking guns but said the K36 primer is an older product, normally used with a different line of urethane paint used on cars.

I plan to sand the paint and primer off and start over. Luckily the material the struts are made of is thick enough that I should be able to do this without hurting anything. I don't envy Dave having to sand the paint off the boot cowl, that must have been tough.

I am going to add some other posts here to try to share what I have learned about painting.

John

[aflyer]

When I built my RV8 (20 years ago) I hired the local airplane painter to paint it, having never painted anything. He did a beautiful job, and it gathered many compliments. As I flew the airplane around (8 times to OSH, and all over the country) the first words out of everyone's mouth was "did you paint it?".

When I decided to build the cub, I determined I would paint it. I have had many learning mishaps, and probably more to come, but no regrets, I knew it would be an adventure.

I have relied on several sources of information: my original painter, who was a sole proprietor of an aircraft paint shop for 30 years, and helped a Lancair builder win Grand Champion Kitplane at OSH a few years ago. He retired 6 months ago and is currently in S. America, so hard to ask questions of him now. Also the local PPG paint store manager who painted cars for 20 years before moving to retail. And of course Dave Embry.

I started with a great phone call with Pete Dougherty of CubCrafters and the production lead and one of the painters. They gave me some good tips on the Polybrush and Polyspray applications, and also Pete gave me a quote for a package of paint from CC. Unfortunately, there was a substantial markup of the paint included, and $1500 truck freight tacked on, which made it hard justify. Even with all my false starts and buying $400 gallons of primer I can't use, I will still save about $4K.

So, I am still learning. I can't really post a set of instructions, but I'll add one more post here for now.

John

[aflyer]

What John thinks he has learned so far...

After a talk with Steve at PPG tech support, it sounds like the newer primers do a good job on bare aluminum. However, he is adamant that the Delfleet topcoats "do not play well" with the etch primers, and that there must be a sealer coat in between. The local paint store manager also said the same thing. The F4943 sealer is interesting in that it is ready for topcoat in 15 minutes, so it is really still just one trip to the paint booth. like an extra coat of paint. So if I were using the etch primer, I would use the sealer.

With covid, a number of PPG products are in short supply, and right now my local paint store can't find any hardener for the F4943 anywhere in the pipeline, and said it could be anywhere from a week to 6 months for a new batch from the factory.

Steve at tech support recommended the F3993 line of primers be used on scuffed bare aluminum. That was also unobtainable.

He also recommended the DPLF line of epoxy primers. The data sheet for these claims "Strong corrosion protection" and that it can be applied over properly cleaned metal. CC already uses this primer for the fiberglass parts, so that gives me one primer for both aluminum and fiberglass. I feel comfortable with this primer over all the alclad parts like the boot cowl too.

And, I can actually get all the components! So, that is where I am headed today. I will report back.

John

[Daveembry]

John,

I know the frustration! It can be quite intimidating. I'm no pro but really enjoy painting myself and I've done some pretty exciting paint schemes on 6 carbon cubs so far. I'll pitch in here with more details that will maybe help out and I'll copy this over to my forum thread.

First, let me just say that I have always enjoyed challenges.....learning new things, as it appears you do too. I enjoyed the fact that other than 3 screws/nuts/bolts in the airplane, I can say that I have done every bit of it solely by myself with no help from anyone else (except hang the wings). Painting has been one part I have enjoyed.

I started painting in a temporary paint booth made from plastic and Harbor Freight fans to a full blown, professional grade, positive pressure paint booth I build in my new hangar (which I also build 100% from my own labor except for concrete and some help with beams). I have the advantage in that at my small airport here in Oklahoma, a HUGE hanger is occupied by someone who has become a good friend and he is the painter of choice of airplanes for most anyone in this area. He uses different products and doesn't paint fabric airplanes.......so he offers no suggestions to me on that aspect but he has helped in all other general areas concerning paint and has been a huge resource for me.

Painting (and other new challenges). Anytime in my life where I've taken on a new project, I've research to find the most knowledgeable, professional and experienced sources I could find...... AND THEN I'VE LISTENED TO THEM.

In this case, I found 2 professionals with the most knowledge and experience out there for painting Carbon Cubs.

1. Cubcrafters (who would I be to question what they have successfully done for over a decade and hundreds if not thousands of airplanes?)
2. PPG, one of the oldest and most professional paint manufacturers in the world for many, many years.

Everything I've done on these airplanes has been based on what CC said to do. (I know, in this case Pete was incorrect about the composite primer but that is a new position/subject for him and new products being used). If they are doing that in the factory, I'm going to do it on my airplanes without question.

DUHS is the PPG paint used by CC for many years. It is a high solids, single stage paint used for many years in the automotive industry that was very user friendly. I don't know if additives were done by CC for increased UV and flex, but they used it exclusively I believe for airplanes that wanted the "glossy" look that you can't get from the Poly Tone paints. PPG stopped making it many years ago and I believe CC purchased the remaining inventory of it.

I know they even experimented with basecoat/clearcoat paints and learned a lesson on that and that is the reason they don't do it now I think. (more info on that as a separate subject below)

Now with the changing environmental concerns, PPG went to the new line of Delfleet Evolution paint and that is what CC moved to when the DUHS they had ran out. This paint to ME....is very different. I don't like it nearly as well and it has substantially different qualities.....but none the less....when done right....it's a very brilliant paint that looks great and is very durable.

So, PPG makes this paint......they have spend their huge $$$'s in research on the best way to use it with the right combination of products to make it work best. CC has used it for the last couple of years I think. So, I'll just stick with what they say and ignore anyone else (well, I might "listen" but most likely not follow their advice over these 2 "professionals" with all their knowledge and experience.)

PPG makes the DATA SHEETS which I reference and you have looked at. Why question them? There are choices among their data sheet on hardeners, speed of accelerator's and/or reducers to use based on heat/humidity......but that's it. Why would you go use some other primer/sealer, etc etc outside their prescribed products to use?

I have used these new paints and they have worked fine, just as they prescribed. Some of the things different in this product over the DUHS is:

1. The acid etching primers they prescribe on aluminum is applied to bare aluminum immediately after scuffing/sanding and only 1 coat is needed. Then paint the topcoat color after 30 minutes. So it's a 1 day operation. You scuff/prime and paint all at the same time. The old primers were much different. Their pot like for like a month, you didn't have to sand it unless you waited like 7 days before topcoat, you used 2 coats instead of 1, etc. A different animal.

2. The primer dries super fast (a couple minutes). If you are not careful and have other items close (like another spar), overspray becomes a concern. It isn't like color coats where your overspray will melt in........ if you spray a something next to a primed part that you painted 2 minutes ago, the overspray will make very rough areas (maybe like you experienced). I learned that....... I just lightly sanded the rough overspray off before putting on the color.

3. I clean parts after scuffing/sanding with denatured alcohol instead of the cleaners. The alcohol dries immediately whereas they say with most cleaners/de-waxers, etc. to wait like 2 hours. Otherwise, the "fisheyes" can appear (from the moisture from the cleaner still vaping off). Also be sure when you use the waxed tack cloths, to be very careful and not "rub" those onto the surface of the part. I wear gloves when handling the parts after cleaning and the tack cloths are very lightly "moved" across the part so as not to rub off/press any of that wax onto the part ....or..... a "fisheye" will appear. This also goes if you've handled the tack cloth in your gloved hand. Wax gets on it and then you grab the part and ..... "fisheye". I tack cloth lightly, then I spray more alcohol onto my gloved fingers that have handled it to remove any way before touching the part again (or change gloves).

4. The color paint is also different. As I've said, it does NOT stick to itself very good. You have to SAND (not scuff) any painted surface with 220-320 sandpaper. Be sure and get every spot sanded so no gloss whatsoever. This is especially hard up next to the fineline tape that you may have down for a stripe or color change point. You have to sand all the way to the very edge of that tape.....or it may peel away when you remove the tape. Always be sure and peel away the tape going away from the painted edge so as not to get it peeling. With the DUHS, I think it would stick to glass! A very light scuff and paint away over it.......not this paint!

5. The color paint dries REAL FAST! The DUHS you could wait 30 minutes between coats at 70. With this paint, it's more like 5-15 minutes, any longer and you will get rough spots, fisheyes, orange peel, etc etc as a result of the paint getting too hard before the fresh paint hits it and blends in. This is hard when painting big areas like the fuse and wings because there is no delay between coats. Finish the 2nd side of the wing and flip it over and start right back over with the 2nd coat on the 1st side. Judge it by touching the edge of the paint (on the taped etc, overspray area) and you will notice it gets "tacky" real quick. You want to hit it with the 2nd coat while a little paint still sticks to your glove when you touch it. I had to completely redo some parts (like you) when I first started figuring this paint out.

6. As I said, this paint dries fast and also get hard far faster than the DUHS did. With DUHS, you had to wait some time at 70 before you could mask, etc but you could also paint over it without scuffing for days! The new paint.....it's a few HOURS. To apply fine line tape to make a new color or stripe, etc on DUHS, I would wait at least 2 days at normal temps (without baking), otherwise.......the tape would dull the gloss where you applied it and you would have to buff/polish to get it out. The paint would continue flow out for days. This Delfleet Evolution is DONE in hours. It's continues to gloss it seems for a few days but you can tape it the next day but you have to always sand it before the next coat over it.

7. I know this isn't your problem with spars because they are metal, but any fabric parts must sit and gas off for 2 weeks before topcoating with color. If you paint color on top of the Poly Spray too soon, you will see tiny bubbles appear (especially over the metal areas like leading edges of the wing, etc) immediately. This gassing of the vapors from the poly fiber materials is what causes the problems when using a basecoat/clearcoat process. The fabric gasses off on BOTH SIDES, outside fabric as well as the inside of the fabric. Basecoat paints are NOT a sealer. If you paint a basecoat paint over fabric and then put a clearcoat (which is a sealer) over it, it will gas THROUGH the basecoat color and perhaps mold/molt/distort (in other words....screw it up!) the basecoat. There is a way around it. You first spray the clearcoat over the fabric (over the poly spray) to SEAL the fabric.....then lay down your basecoat color on top of that.....and then back with the clearcoat. Heavy and clearcoats still want to crack in some areas (like around the grab handle). So why fool with it. Much easier to use a single stage.

I use a local PPG dealer here in Tulsa. The salesman is a friend and is super knowledgeable about the product and he works every day with the companies in the field that he sells this Delfleet Evolution paint to. It's used primarily on the heavy duty, fleet trucks because of it's durability and ease of use. He can make me up a quart of the paint in an hour and have it ready and stocks most everything on the shelf and the cost is fractional to where I have been getting it before (CC).

So I hope this sheds some light on the subject and my humble suggestion would be to not over think or over engineer this product and go with what the manufacturer and most experiences airplane builder (CC) says to do. A painter that painted an award winning RV has nothing to do with a paint process that was recently engineered by the world's leading automotive paint manufacturer and one that is used by a very successful and innovative aircraft company. I'm not "dissing" your painter.....it just that things change and just because one product line is used one way or the other makes no difference on the current products.

What John thinks he has learned so far...

After a talk with Steve at PPG tech support, it sounds like the newer primers do a good job on bare aluminum. However, he is adamant that the Delfleet topcoats "do not play well" with the etch primers, and that there must be a sealer coat in between. The local paint store manager also said the same thing. The F4943 sealer is interesting in that it is ready for topcoat in 15 minutes, so it is really still just one trip to the paint booth. like an extra coat of paint. So if I were using the etch primer, I would use the sealer.

With covid, a number of PPG products are in short supply, and right now my local paint store can't find any hardener for the F4943 anywhere in the pipeline, and said it could be anywhere from a week to 6 months for a new batch from the factory.

Steve at tech support recommended the F3993 line of primers be used on scuffed bare aluminum. That was also unobtainable.

He also recommended the DPLF line of epoxy primers. The data sheet for these claims "Strong corrosion protection" and that it can be applied over properly cleaned metal. CC already uses this primer for the fiberglass parts, so that gives me one primer for both aluminum and fiberglass. I feel comfortable with this primer over all the alclad parts like the boot cowl too.

And, I can actually get all the components! So, that is where I am headed today. I will report back.

John

[jmorrical]

Interesting detailed information here. Dave I’m about to prime most large aluminum parts. I’ve spent some effort to hang them in order to make this as efficient as possible. Your comments about overspray has given me some concern.

I can surly give a light sanding to knock down any overspray. Would you spray as is or separate parts more?

5948F7EA-3F8E-4E90-9C06-B785DC33FDE2.jpg

[Daveembry]

i would I think. For example I had 4 spars in paint booth at same time. They were hanging from cross wires I use about 4’ apart and nothing else in the booth and I had problems. The old primers didn’t do it but this aluminum primer is different. When you first spray it on, it looks terrible. Lumpy and blotched but as it dries in just a couple of minutes, it smooths out and looks fine. It seems like then when more paint hits it, like overspray, it puffs up and it’s like little grains of sand. It didn’t do it from just the primer in the air but with any direct overspray out of the gun (like spraying 1 piece and it directly hitting another part)

The primer dries so fast that I just carried 2 in and hung them and sprayed each one facing opposite directions. I gave them a few minutes to dry and removed them from the booth and did the other 2. Then I brought the first 2 back in and painted all 4 at the same time with color as usual and no problems. That’s the way I prime now with this primer.

I did the same thing the first time on flaps and ailerons. Had to sand them all down. Uggg.

Interesting detailed information here. Dave I’m about to prime most large aluminum parts. I’ve spent some effort to hang them in order to make this as efficient as possible. Your comments about overspray has given me some concern.

I can surly give a light sanding to knock down any overspray. Would you spray as is or separate parts more?

5948F7EA-3F8E-4E90-9C06-B785DC33FDE2.jpg

[aflyer]

Thanks Dave. This is turning into a great resource thread for anyone starting out as a painter!

Your point about overspray is well taken, and probably part of the problem with my spars. I have been careful to always paint downstream in the paint booth (from inlet end to outlet end), but parallel parts are dangerous too.

I modeled my paint booth after the one Bill Rusk built ("Building a Javron Cub" on supercubs.org, a great resource thread). It is working very well. When I finish the second wing (tomorrow) I will shrink it down to 12' long for the rest of the project, which is all happening in one hangar.

John

[Daveembry]

I was going to add that:

- when you sand the gelcoat off the carbon fiber parts (cowl, extended baggage door, main door, etc) it is "GRAY". Since I was told not to prime these parts, I painted 3 airplanes so far WITHOUT PRIMING the composites and they have all been perfect with no problems with adhesion or color. I do scuff them good with burgundy scotchbrite pads. THey matched the boot cowl perfect and it was aluminum and primed. BTW, the aluminum primer is GREEN, not GRAY like the composite primer is.......so there is no base color match anyway.

The colors I have painted so far is light gray (Grizzly); dark gray (Ol' Glory) and the latest was Firecracker red.

In the past I have painted white and orange and it does take 2 good coats normally (even when all primed) to give good coverage and hide the background color.

Thanks Dave. This is turning into a great resource thread for anyone starting out as a painter!

Your point about overspray is well taken, and probably part of the problem with my spars. I have been careful to always paint downstream in the paint booth (from inlet end to outlet end), but parallel parts are dangerous too.

I modeled my paint booth after the one Bill Rusk built ("Building a Javron Cub" on supercubs.org, a great resource thread). It is working very well. When I finish the second wing (tomorrow) I will shrink it down to 12' long for the rest of the project, which is all happening in one hangar.

John