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Tip: Cutting and Buffing Paint

If you are only doing one job, you might ask your buddies if there is one to be borrowed. That said, I find I am doing more and more finish projects so I splurged for a dewalt variable speed with soft start (avoids some of the compound flinging) :)

And you can even tell her it was on sale....:)

This Item Is Included in Our DEWALT $25 Off $100 Holiday Promotion. From November 26, 2014, to December 22, 2014, when you spend $100 or more on select DEWALT tools and batteries shipped and sold by Amazon.com you can get $25 off at checkout.
 
Thanks, Dan

I'm so glad I found Dan's awesome thread. Years ago I painted my plane with PPG Durathane and results were pretty bad in the orange peel department. I put the stuff on pretty thick so after reading this thread, I have hope that I can fix it. Since the original paint job, I have modified my cowling for a different exhaust system, and have been flying it in primer. Sadly, it appears that Durathane is no longer manufactured, which is sad because it has been fantastically durable and is highly chemical resistant. I have been looking for something similar but all I can find is Imron 3.5 HG at $255 per quart. Ungggh! Any suggestions would be highly appreciated since painting weather is rapidly approaching
 
PPG Deltron DBC basecoat and DCU2021 clear is holding up very well at 6 years into the game.
 
Thanks for the tip but I'm going to stick with the single stage polyurethane paint. It's just plain white.
 
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I'm so glad I found Dan's awesome thread. Years ago I painted my plane with PPG Durathane and results were pretty bad in the orange peel department. I put the stuff on pretty thick so after reading this thread, I have hope that I can fix it. Since the original paint job, I have modified my cowling for a different exhaust system, and have been flying it in primer. Sadly, it appears that Durathane is no longer manufactured, which is sad because it has been fantastically durable and is highly chemical resistant. I have been looking for something similar but all I can find is Imron 3.5 HG at $255 per quart. Ungggh! Any suggestions would be highly appreciated since painting weather is rapidly approaching

Take a look at "engineered siloxane" resins such as PPG PSX 700 or Sherwin Williams XLE-80. No isocyanates, low viscosity so sprays fine without thinning, tough as epoxy, UV and chemical resistance better than polyurethane, goes onto bare metal, legal even in California.

Here's a good place to buy pigments and dyes: https://www.paintwithpearl.com/. This is their Sapphire Blue Candy Pearl (10% by weight two light coats followed by clear, cut&buff, ~6 mil total thickness, about 16 lbs per airplane) after a few months of practice and an upgrade to DeVilbiss GTi Pro with T110 aircap (Harbor Freight guns will result in a Harbor Freight finish; ymmv):

2h50i7t.jpg


Perhaps if we all ask very politely, DanH will find the time to update the photo links in this most excellent thread. :D
 
Tape Line?

Is that a tape line!? IMHO, that is going to be somewhere between very difficult and impossible to blend. Paint spot repairs with blending, by their nature, require a tapering of the new paint thickness down to zero where it transitions to the old paint (the blend). You usually shoot the paint to a feather edge out a good ways from the actual repair area. The photo shows a large "step" (tape line) and very little surface area of new paint in which to create the "taper".

If I was going to attempt it, I would probably tape back close to the tape line again (to protect the old paint from the abuse to come at the line) and then a bit of scraping using a razor blade to knock the step down a bit (starting the taper) and then move to wet sandpaper on a block to move the taper out into the new paint. Remove the tape at some point and gradually use finer paper (always on a block), extending the blend into the old paint and then eventually move to buffer etc. Very tedious at best and I wouldn't want to bet on a good outcome (invisible blend).

Just my 2 cents based on my painting experiences.
 
paint block

I cannot remember the proper name but you can get a metal block that can shave cured paint. Like you I used a single stage paint (PPG DCC Concept) with no clear coat and then followed Dan's thread to cut and buff the orange peel, I bought the metal block to work small areas that I could not cut and buff easily.

My plane is basically all white and the PPG still looks good after 10 years http://pilotsareus.com/blog/

Figs
 
No not a run razor, looks like this https://www.eastwood.com/painters-nib-file-fine.html?SRCCODE=PLA00020&gclid=EAIaIQobChMI7LeOzc7E2wIVjobACh1VcQhAEAQYAyABEgL5UfD_BwE, called a painters nib file and is used to cut down painr runs. Tedious but works.
Figs

These metal blade solutions can make a sneeze into a two-day repair...
I find that the 3M thin rubber pad found at auto stores works best for runs and sags, and for blending too. It is just slightly convex and thin enough to focus pressure on the run/blend but still keep the flatness around it.
 
Anyone know the best way to blend something like this? It's single stage Full-Thane.

A quick googling doesn't reveal whether "Full-Thane" is a polyurethane or "acrylic urethane" blend, but in general polyurethane cannot be repaired. It won't bond to itself once fully polymerized. You'd have to strip the entire cowl and re-do. There may be chemical ways of altering it so it takes on more paint, but probably not worth the effort given the potential for damaging the surrounding paint.

Edit: one of the advantages of siloxane-epoxy resin is that it will chemically bond to fully polymerized epoxy (or to itself) without sanding. I wonder if it would stick to polyurethane too? Any chemists on here who can chime in?
 
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acrylic urethane

That is one of the nice things about the PPG DCC concept in that you can scuff up the surface and shoot another coat to fix dings etc. In addition the local automotive paint supplier can prep a matched paint rattle can for about $30. Did this last annual to touch up the wheel pants and it worked well enough for me.
Figs
 
A quick googling doesn't reveal whether "Full-Thane" is a polyurethane or "acrylic urethane" blend...
Sorry, I was misspelling it. It's Ful-Thane and is a "urethane single-stage topcoat". I used Nason® SelectSeal™ 422-51™ 2K Urethane Sealer (white), underneath. I sprayed the top coat on the sealer after a 30 minute wait. I originally painted my plane with PPG Durathane which I dearly loved but you can't buy it any more.
 
Razor Blade Trick

So today I used the razor blade trick to taper down the new paint. It worked pretty well but I have two recommendations. First, putting the razor blade in a vice and using a steel rod to curl over the edge seemed to work better than the 600 grit. I tried it both ways. Second, be sure to put a small piece of tape on the side facing you because it's almost impossible to tell which edge has the curl.

hTJZWB.jpg


After using the razor blade, I went to my tiny little Ace Hardware sanding block with 120 grit on the raised edge.

3CVVp8.jpg


After that I went to 320 grit on a 3M hard rubber pad, then 600 grit. It came out nice and smooth, but I can see different color bands. Whether I sanded through the top coat and exposed the white sealer, or whether the paint match wasn't quite perfect, I don't know, but it's good enough for now. Eventually, I'll have to reprint the entire canopy top (if I care).
 
No Pictures?

Am I the only one that can't see any of the pictures on the first 3 or 4 pages of this post? I can see the pictures in the last few pages.
 
Recommendations

Take a look at "engineered siloxane" resins such as PPG PSX 700 or Sherwin Williams XLE-80.

Aluminum -

I have a few Paint with Pearl pigments. I am ultimately hoping for a ghost blue pearl on white, and a metallic red. The SW metallics are not acceptable, as you need to shoot them from the base coat up in the same color, and my design has too many transitions to make that anywhere near affordable.

A few questions if you would not mind:
1) What do you suggest to use for a clear coat to shoot a ghost pearl over the XLE-80?

2) Do you know if SW makes a satin instead of a gloss white in the XLE-80 line?

3) What do you recommend as a actual source to buy the SW paints?
 
Aluminum -

I have a few Paint with Pearl pigments. I am ultimately hoping for a ghost blue pearl on white, and a metallic red. The SW metallics are not acceptable, as you need to shoot them from the base coat up in the same color, and my design has too many transitions to make that anywhere near affordable.

A few questions if you would not mind:
1) What do you suggest to use for a clear coat to shoot a ghost pearl over the XLE-80?

2) Do you know if SW makes a satin instead of a gloss white in the XLE-80 line?

3) What do you recommend as a actual source to buy the SW paints?

Ah, #1 is easy: nothing goes on top of polysiloxane except more of same! It's silly how slippery that stuff is once fully cured. The good news is it can later be recoated with itself without sanding, no loss of adhesion. It is extremely glossy as a topcoat and resists UV and chemicals better than polyurethane.

Sorry can't help with #2 and #3 as I never tried the SW version. I imagine any SW retail store should be able to order. PPG does have a semi-gloss version: PSX 700SG. I bought mine (high gloss clear) from here.

I tried a couple of interference pigments ("ghost pearls") in PSX 700 without success so far, but neither attempt was over black base. I'll do a proper test one of these days of untinted interference flakes over black and report what I find. Note that many pigments look different inside siloxane epoxies from their "normal" color inside acrylic topcoats or intercoats; I suspect different index of refraction of the resin, as opposed to chemical reaction. That might be what's ruining the interference effect. More research required.

I also tried PSX 700 clear over white Akzo epoxy primer (i.e. plain titanium dioxide tint), both applied with foam roller. After cutting and buffing this resulted in bright glossy white mirror finish shinier than any airplane at my home field. :D If you are not planning on metallics, have a lot of free time (roller deposits very thin coats) and don't mind wet-sanding the entire airplane twice, this could be an inexpensive and environmentally friendly way of getting a top notch finish that is lightweight and durable.

By the way, in case it's not clear from the manufacturer's instructions: siloxane epoxies stick to bare metal, no primer needed. Simply alodine and shoot pigmented then clear.
 
without success so far

Dan V,

I thought the ghost pears were to be mixed with clears, and shot over the base coat, not in it. At least that is what the Paint With Pearl page says (unless I am misreading it). Maybe that is causing the lack of success? That is why I asked about a clear coat.

If you were doing your plane with a pearl and using a clear coat, would you shoot PSX 700SG over the XLE-80, or would you do a tinted base of the PSX 700SG, and then shoot a clear coat over that?
 
I thought the ghost pears were to be mixed with clears, and shot over the base coat, not in it. At least that is what the Paint With Pearl page says (unless I am misreading it). Maybe that is causing the lack of success? That is why I asked about a clear coat.

Correct. So, the complete procedure would be:
- clean&etch
- alodine
- shoot black, wet sand if not flat
- shoot interference flakes or ghost pearl pigment--do not sand!
- shoot clear, wet sand and polish

The interference effect is relatively faint, the black base helps bring out the contrast. A light base overwhelms the colored reflection from interference flakes.

If you were doing your plane with a pearl and using a clear coat, would you shoot PSX 700SG over the XLE-80, or would you do a tinted base of the PSX 700SG, and then shoot a clear coat over that?

I wouldn't mix the S-W product with the PPG product. Although they are supposed to use similar chemistry it's not a given that they are compatible. Use the same resin for all coats. Alternatively, you can use any epoxy primer as first coat as the siloxane will keep it from chalking.
 
I can serve as a bad example!

DanH has put together a great thread here showing us all how it should be done. I'm just an amateur who hates painting, but maybe it would be useful for everybody if I posted a few examples of how it should NOT be done. First of all, your cutting and buffing will go a LOT better if you do a good job of applying the paint in the first place. In my case, I used a cheap Harbor Freight Binks-knockoff siphon gun, and really didn't have a good spray booth. Two strikes against me. There are a lot of tricks to adding the proper amount of reducer to the paint so that it will flow evenly without runs or sags with minimal orange peel. I guess I didn't know any of those tricks because I got all of the above. You won't get runs and sags if your workpiece is horizontal, but that is hard to do on a fuselage or if your aileron is hanging vertically from some wires so you can do both sides at once.

You will really want to minimize dust or other debris while spraying, so you should cover the floor of your spray booth with butcher paper or wet it down with a garden hose. You don't want to spray when it's windy. I didn't do any of those things with this last attempt, and here are the results:

aYn4pB.jpg


The good news is that all those "dust nibs" (I think they're called) sanded out, but it took some time and effort. I should mention that I'm using single-state Urethane paint (Nason Ful-Thane) which seems to work pretty well for a klutz like me. I started with 800 grit to remove 80% of the defects, then switched to 1200 grit for the last 15%. Yes, this is not a show plane so I'm willing to accept an occasional defect here and there. After that, I went to 2000 grit wet-or-dry and that made the surface almost shiny, but I can still see some faint scratches. I bought some 3000 Trizact discs which I will be using tomorrow. After that, I intend to use 3M "Perfect-It" compound #1, then #2 if necessary.

One thing I've discovered is that a foam 3M hand pad cuts almost as fast as the DA sander, and doesn't leave swirl marks. This has been an adventure.

PxboAC.jpg
 
I sense a lack of interest here, but I'm done cutting and buffing the wings. After the 3000 Trizact, I buffed with 3m Perfect-It #1 using a wool pad.

0F8tct.jpg


In the bright sun, I could see swirl marks so I bought a qt. of #2 polishing compound ($64 at the local paint shop!!!), and applied that with a flat foam pad. You definitely will want to mask off any control surface gaps and hinges lest you gunk them up with compound. It would also be smart to mask off adjacent areas because that compound slings everywhere.

qxsq8Q.jpg


After cleaning off the #2 Polishing compound, I could still see some fine swirl marks, but I said "screw it". In the shade, my wings have a mirror finish now.

Cv2Iu6.jpg
 
John, nice job.

If I were fine-tuning a new guy in the detail shop...

We quit wool pads years ago. There are polish pads available, but most of the common wool pads are cutters, a method which predates the fine grit abrasive disks you used. I think you would have had fewer swirl marks using a 3M white foam pad. Switch to a black pad for the swirl remover.

The photos appear to show too much compound. You want enough to wet out the surface, but not so much that the pad surfs up off the surface on a layer of liquid. Buff to near (but not quite) dry. You'll hear the machine begin to load up, and the pad will get warm. Go less dry with the last polish/swirl remover step. Think of it this way; we're removing material to make the surface microscopically flat, not adding material, as we would with a wax application.
 
You definitely will want to mask off any control surface gaps and hinges lest you gunk them up with compound. It would also be smart to mask off adjacent areas because that compound slings everywhere.

Of the two kinds of compound I used neither mentioned a key piece of info on the container: it is in fact water-soluble. A foamy bath with microfiber cloth will remove most residue from crevices. But yes, keep the compound out of hinges and bearings as it will abrade them in principle (no cause for worry in practice, very soft abrasive).

Concur with DanH on the use of foam discs not wool bonnets (Harbor Freight ones are fine); they come in different foam stiffness for different steps and leave no swirl marks. After use I wash away the goop from the foam under running water and centrifuge it out at max speed, they last a long time that way. Pro videos show removing dried compound with a screwdriver. I don't like this method as it makes airborne mess and ruins the foam quickly.

Contamination from residue of coarser grade compound will leave visible swirl marks, must wash well between steps!
 
Dan H and Dan V: Thanks for the encouragement and tips. I still have to cut and buff the fuselage so I'll ditch the wool pad and go with foam pads from Harbor Freight. Question: Will waxing hide swirl marks? I don't want to wax yet because I intend to paint some colored trim first.

P.S. The foam pad I used with the Perfect-It #2 said, "Machine Wash" so that's what I did. I tossed in the washing machine with my microfiber cloths on the "delicate" cycle. The foam pad seemed to come through that process intact. LOL!
 
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uk_figs little nib file got me to thinking. It looked exactly like my Dad's old aluminum file that I had in the tool box. So I got it out today and tried it out. It worked great for removing drips and runs on a convex surface. The serrations cut right into the drips and sags, but skittered right across the adjacent areas without cutting them. Thanks for the tip, Figgs!

eHdFU6.jpg
 
I have a bunch of cutting and buffing to do - really appreciate this on-going discussion. Haven't yet found the Trizact discs locally so am planning on doing 600 wet, 1000 wet, 2000 grit 3M Perfect-It buffing compound and 3000 3M polishing compound. I have the 3M foam pads and they seem to work well. Don't have the ability to use air tools (limited by electrical supply, can't run a big compressor) so will be doing it all with electric tools. Have a Makita 7" professional variable speed polisher and a Porter-Cable 6" variable speed random orbit polisher. I'm open to suggestions, given these limitations, of the best way to move forward.
 
It seemed to me that hand sanding worked just as well (or maybe better) than using the DA, so I think you'll be fine. The Trizact seemed to work a LOT better than the plain papers, but I only used the 3000 grit Trizact. If I had it to do over again (oh wait, I still have my fuselage to do), I would use the Trizact 1000 and 1500 before the 3000. Amazon.com carries the Trizact products; They deliver to Canada, right? Don't worry, if a klutz like me can do this, anybody can.
 
uk_figs little nib file got me to thinking. It looked exactly like my Dad's old aluminum file that I had in the tool box. So I got it out today and tried it out. It worked great for removing drips and runs on a convex surface. The serrations cut right into the drips and sags, but skittered right across the adjacent areas without cutting them. Thanks for the tip, Figgs!

.....]

Looks like one of the ready made versions is the same thing, but shortened way down and with the edges rounded off to prevent digging in -

STE35250.jpg


http://www.tcpglobal.com/STE35250_2.html#.WzFTo6dKhhE

Looks really easy to make a DIY copy. :)
 
Flexible Vixen Files

I'm not sure these would work better, but you can buy 14-inch Flexible Vixen Style Body Files
The unique feature of these files (not available on most body files) is their convex cross section. The cutting area is not flat, but higher in the middle than on the beveled edges. This tiny (1/64") height difference keeps the edges of the file from coming into contact with the workpiece, thus preventing gouges, which means the filed surface can be painted with only minimal intermediate finishing. These files are available in five cuts, ranging from special coarse to fine (see chart). Both faces of each blade have the same cut. These files are drilled and countersunk for attaching to file holders. 14" bent length.
 
OK, I've got my fuselage wet sanded to 2000 grit and will be using the 3000 Trizact today. I have a question for the experts, though. Which would work better for buffing and polishing, my 9" Milwaukee buffer or my 6" dual action? I need to know before I buy the recommended foam waffle pads. Thanks in advance.
 
Not hearing back, I bought some smooth foam pads for my 6" DA at Harbor Freight. They come in "Compounding" (or correcting), "Finishing", and "Polishing". I just bought the first two. I guess I'll just try them and see how they do. I also bought a couple larger foam pads for my buffer, but they're Hookit and my buffer just has a rubber pad. I really don't want to spend $60 buying a Hookit backing pad for my Milwaukee.

I also found The Ultimate Beginner?s Guide to Buffing Pads. The site recommends Griot?s Garage Flat Pads for beginners. That would be me. ;)
 
I finished the fuselage, such as it is. Not hearing back from the "experts" here, I used my 6" DA sander with a foam pad to apply the 3M Perfect-It #1 compound. That was a bad mistake. I had previously wet sanded the fuselage up to 3000 grit Trizact, and it was very smooth, but hazy. After buffing with the DA, it had deep, oval-shaped swirl marks which the #2 and #3 compounds wouldn't remove. The wings came out pretty shiny (with light swirl marks) using the wool pad on my rotary buffer for the #1 compound, and a flat foam pad for the #2 polishing compound. I never used the #3 ultra-fine on the wings. Since the wings came out so well, I should have ignored the "expert" advice against using the wool pad and done the same on the fuselage. As it was, I wasted a week's work and ended up with a mediocre job. Now, if I want a good finish, my only option is to drop back and re-sand the fuselage with the 3000 Trizact (or maybe even 2000) to remove the heavy swirl marks left by the DA and foam pad. Hopefully there is enough paint left to do that if and when I decide to. If there are any lessons here, they would be, 1. DO NOT use a DA sander for buffing, and 2. Use your own judgement instead of listening to "experts".
 
Hmmm, I use a variable speed rotary for all of it (buffing). Not sure how you avoid edge burn with a DA. I always buff "off" at the edges. Only takes and instant if you hit it the wrong way to take the paint off.
 
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I finished the fuselage, such as it is. Not hearing back from the "experts" here, I used my 6" DA sander with a foam pad to apply the 3M Perfect-It #1 compound. That was a bad mistake. I had previously wet sanded the fuselage up to 3000 grit Trizact, and it was very smooth, but hazy. After buffing with the DA, it had deep, oval-shaped swirl marks which the #2 and #3 compounds wouldn't remove. The wings came out pretty shiny (with light swirl marks) using the wool pad on my rotary buffer for the #1 compound, and a flat foam pad for the #2 polishing compound. I never used the #3 ultra-fine on the wings. Since the wings came out so well, I should have ignored the "expert" advice against using the wool pad and done the same on the fuselage. As it was, I wasted a week's work and ended up with a mediocre job. Now, if I want a good finish, my only option is to drop back and re-sand the fuselage with the 3000 Trizact (or maybe even 2000) to remove the heavy swirl marks left by the DA and foam pad. Hopefully there is enough paint left to do that if and when I decide to. If there are any lessons here, they would be, 1. DO NOT use a DA sander for buffing, and 2. Use your own judgement instead of listening to "experts".

What's a "DA sander"? I use this DeWalt polisher and HF foam pads and never had any issues with scratches from compound, neither the "Meguiar's" brand sold at HF nor the 3M 1-2-3 system. I suspect your compound or pads got contaminated; either that or you had deeper cuts left over from coarser grits that weren't visible after 3000 grit but got conspicuous after the flat areas got shiny.

Finally, I'm no "expert" at this hobby by any stretch of imagination, but was able to achieve amazing results following DanH's advice (see post #55). It did take several months of practice to get there, though, and I'd still rate my performance a "B-". The lesson you learned the hard way is: don't change any parameters of a successful painting process without first testing and re-testing on scrap.

Nobody said it was going to be easy! There's a reason pros charge ten grand for a paint job. Hang in there and you'll be proud of the result for many years.
 
I suspect your compound or pads got contaminated; either that or you had deeper cuts left over from coarser grits that weren't visible after 3000 grit but got conspicuous after the flat areas got shiny.
Nope and nope. The pads were brand new and I wiped down the fuselage after the #1 before going to the #2. Then I switched to a brand new softer pad. No contamination. The "deeper cuts" are oval shaped from my 6" Dual Action Sander and they weren't there after the 3000 grit. The DA and foam pad I used were just too aggressive with the #1 compound. Sorry, but I can't be consistent because I've never done this before (except for the wings which came out pretty well but everybody said not to use the wool pad so I didn't on the fuselage with poor results). With the wealth of knowledge here, I was hoping to get some practical advice before I did something wrong but beggars can't be choosers, I suppose.
 
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It looks like I'll be able to salvage my paint job. I chose a test patch on the top of the fuselage and tried to sand out the swirls with 3000 grit Trizact. It wouldn't cut it (pun intended). So I dropped back to 2500 grit wet-or-dry with a hand pad and that removed the swirls quite nicely using a 0/90 +45/-45 crosshatch pattern. Here's what the swirls looked like before:

ZN4HPG.jpg


Nasty, huh? I did the rest of the fuselage top with the 2500 grit and got all the swirls out. I plan to just repair the top and sides and forget about the underside where the sun don't shine. Next I'll go over it with the 3000 Trizact, then back to the 3M Perfect it. I'm thinking of skipping the #1 compound and going straight to the #2. I'll try a test patch and see how that works. I'll probably apply it with a microfiber pad for a true hand-rubbed finish. I'm scared of buffers now :eek:
 
You want practical advice? Stick to the tools and techniques detailed in the initial thread posts.
 
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