Van's Air Force
Don't miss anything! Register now for full access to the definitive RV support community.
Severe orange peel
- Thread starter jayres
- Start date
Was it over the hwole airplane, or on some parts? Since you called it severe, I would recommend stripping. It can be accomplished by sanding, but with some of the high gloss paints, you can think you have it sanded smooth until you repaint. Then it looks like you have orange peel again, but it is in fact due to the original imperfections in the substrate.
have you figured out the original cause? Usually, orange peel is caused byu putting the paint on too dry or too hot, thereby not giving it a chance to flow out.
Vic
have you figured out the original cause? Usually, orange peel is caused byu putting the paint on too dry or too hot, thereby not giving it a chance to flow out.
Vic
Vic,
It's a rather long story but I'll try to keep it short. The orange peel is pretty much all over the plane but random (not everywhere). The first coat was bad but not too bad. I think the original cause was because I didn't know to stop and let the compressor build up pressure when it started running low (I thought that once I started, I had to spray contiuously until the panel was covered). Once the pressure got low, the paint wasn't atomizing properly and consequently, not flowing out either. Then I had the bright idea of using an HVLP sprayer that I bought from Harbor Freight for $40 (big mistake). I only sprayed the fuselage this time. Perhaps the substrate was part of the problem (I did lightly sand it but not much). This time the paint really didn't flow, resulting in severe orange peel everywhere I sprayed (which is pretty much the whole upper fuse and cowl. I did have the wings and tail section covered. I believe that cause of the severe orange peel on the second coat was due to the sprayer not atomizing the paint (again but much worse than the first time). I had the paint reduced at twice the recommended ratio, so I don't think I was spraying too dry. This is only my opinion and my paint experience and knowledge doesn't go much beyond painting a few houses.
Jimmy
It's a rather long story but I'll try to keep it short. The orange peel is pretty much all over the plane but random (not everywhere). The first coat was bad but not too bad. I think the original cause was because I didn't know to stop and let the compressor build up pressure when it started running low (I thought that once I started, I had to spray contiuously until the panel was covered). Once the pressure got low, the paint wasn't atomizing properly and consequently, not flowing out either. Then I had the bright idea of using an HVLP sprayer that I bought from Harbor Freight for $40 (big mistake). I only sprayed the fuselage this time. Perhaps the substrate was part of the problem (I did lightly sand it but not much). This time the paint really didn't flow, resulting in severe orange peel everywhere I sprayed (which is pretty much the whole upper fuse and cowl. I did have the wings and tail section covered. I believe that cause of the severe orange peel on the second coat was due to the sprayer not atomizing the paint (again but much worse than the first time). I had the paint reduced at twice the recommended ratio, so I don't think I was spraying too dry. This is only my opinion and my paint experience and knowledge doesn't go much beyond painting a few houses.
Jimmy
Sand and re-shoot.
Assuming your paint will let you get away with it (no solvent lifting) you can sand smooth with 400-600 wet - try not to sand through the paint - and re-coat one more time. HPLV guns are really tough for first-timers. Since you only have to do it once (one big project) get an old school siphon gun (Binks BBR is my favorite). You will get better results but use more product and make a bigger mess in your shop. Reduce as per instructions! Thinning can cause as many problems as anything, and because it will take more coats to cover, you will have more orange peel build up.
ff
Assuming your paint will let you get away with it (no solvent lifting) you can sand smooth with 400-600 wet - try not to sand through the paint - and re-coat one more time. HPLV guns are really tough for first-timers. Since you only have to do it once (one big project) get an old school siphon gun (Binks BBR is my favorite). You will get better results but use more product and make a bigger mess in your shop. Reduce as per instructions! Thinning can cause as many problems as anything, and because it will take more coats to cover, you will have more orange peel build up.
ff
As the previous poster said, you could sand with 400-600 grit, but be careful to make sure that you sand it flat. I t could look sanded properly, but the application of paint will still show the previous orange peel. You can sand it, and then put a film of water on it, let the light catch it just right, and you might be able to tell if the orange peel is still there.
Get a compressor that will keep up with the gun. That's a must. And run a long enough length of hose to let the air cool down. I use a water trap right at the compressor, then another trap at the junction of two 50' hoses. If the air is still hot, coil up some of the hose and put it in a bucket and cover it with ice cubes.
Vic
Get a compressor that will keep up with the gun. That's a must. And run a long enough length of hose to let the air cool down. I use a water trap right at the compressor, then another trap at the junction of two 50' hoses. If the air is still hot, coil up some of the hose and put it in a bucket and cover it with ice cubes.
Vic
I forgot one other thing. I put an extra fan right by the compressor blowing on the compressor cylinder. It keeps it much cooler that just the flywheel fan on the compressor.
Vic
Vic
cytoxin
Well Known Member
mine had an unbelievable amount of orange peel. i thought i could paint
...
wetsand and buff if you have three coats or more. if not wetsand and shoot one final slick coat..i dont see the need to strip at all. you need a decent base/primer to paint on and you would have to do that all over again.
Note: if you use a DA sander with 500 +- 100grit on an interface pad it will sand smooth and flat...sand by hand and you will transfer alot of the orange peel as vic said.
...wetsand and buff if you have three coats or more. if not wetsand and shoot one final slick coat..i dont see the need to strip at all. you need a decent base/primer to paint on and you would have to do that all over again.
Note: if you use a DA sander with 500 +- 100grit on an interface pad it will sand smooth and flat...sand by hand and you will transfer alot of the orange peel as vic said.
Last edited:
frankh
Well Known Member
Just a minute
Hold on there Jimmy,
Your casting dispersions before you know the cause i think. Not saying you didn't get a bad gun but that would be most unusal. Those HF guns are excellent usually IF you know how to use them right.
As others have said wet sanding should be fine assuming you have a good adhesion.
Then you need a decent sized (OIL FREE) or at least a compressor where you KNOW you won't get oil carryover.
Then for heavens sake make sure you PRACTICE on an old metal shelf BEFORE you paint the airplane.
Wind up the pressure at the gun to 40 psi with the trigger pulled.
Load paint and mix it down about an extra 10% over what it says on the can.
Then set up the cigar shaped spray pattern with the correct mixture..spray on the shop wall. pull the trigger full on then off and examine the pattern....Get this right before doing anything else.
www.hotrodders.com and do a search and print out the spray pattern..it will give examples of good and bad.
The practice getting a full wet coat on the metal shelf...Then do the same thing with the shelf propped vertically.....spray while moving..
When you got all that down then paint the airplane...
There is quite a bit to learn but don't just immediately assume its the equipment cus it probably aint! I say this bacause if you were getting orange peel you would have stopped after the first panel..That tells me this is your first attempt.
its a skill like anything else.
Frank
Hold on there Jimmy,
Your casting dispersions before you know the cause i think. Not saying you didn't get a bad gun but that would be most unusal. Those HF guns are excellent usually IF you know how to use them right.
As others have said wet sanding should be fine assuming you have a good adhesion.
Then you need a decent sized (OIL FREE) or at least a compressor where you KNOW you won't get oil carryover.
Then for heavens sake make sure you PRACTICE on an old metal shelf BEFORE you paint the airplane.
Wind up the pressure at the gun to 40 psi with the trigger pulled.
Load paint and mix it down about an extra 10% over what it says on the can.
Then set up the cigar shaped spray pattern with the correct mixture..spray on the shop wall. pull the trigger full on then off and examine the pattern....Get this right before doing anything else.
www.hotrodders.com and do a search and print out the spray pattern..it will give examples of good and bad.
The practice getting a full wet coat on the metal shelf...Then do the same thing with the shelf propped vertically.....spray while moving..
When you got all that down then paint the airplane...
There is quite a bit to learn but don't just immediately assume its the equipment cus it probably aint! I say this bacause if you were getting orange peel you would have stopped after the first panel..That tells me this is your first attempt.
its a skill like anything else.
Frank
Allen231ah
Well Known Member
I used PPG concept topcoat and used the hot weather reducer even though i applied the paint in cold weather,also i increased the amount of reducer by about 5% . This will allow the paint to flow out better but also makes it easier to get runs and sags . Do a light tack coat and come back in about 10 to 15 min with 2 or 3 cross coats . You may be able to wet sand and apply a light coat of color or possibly a clear coat . Be sure you have enough dry air , low air pressure will not atomize the material . I used a Sata gun but a good Binks conventional gun will work fine . I'm not a big fan of the budget HVLP .
If you're going to re-shoot, do as William said, random orbital sander, 3M Hookit or Hookit II pad, a box of the new Trizact discs in 500. There's a foam interface pad too, if you want to use it for the curved surfaces. I like to sand wet, others like dry, and I think you can go both ways with this stuff.
Yesterday I sprayed a whole series of test passes on a 4x4 steel sheet I have propped against the booth wall just for gun setup. Spraying PPG DCU2021 clear, I could not find any setting for a new Sata 90-2 HVLP that would match the HF 43430. Tried the book settings, then off-the-card stuff too, like 35 psi inlet, full fan, and low paint volumes to maximize atomization. The 43430 at 45 psi (at the gun, not the regulator), full fan, and 2 turns out on the needle would shoot slick enough to read the labels on the flourescent light bulbs across the room. However, the effective fan width is not more than 6" or so and I'd like to cover more per pass.
Got no axe to grind here; believe me, at $320 I want the Sata HVLP to work. Maybe it was a dumb buy. I tried a Sata 90-2 RP a few weeks ago. It was better, so I may see if my paint guy will swap and I'll try to fine tune an RP. Sata advice would be very welcome. Before the 43430 I shot everything with a Binks #7.
Yesterday I sprayed a whole series of test passes on a 4x4 steel sheet I have propped against the booth wall just for gun setup. Spraying PPG DCU2021 clear, I could not find any setting for a new Sata 90-2 HVLP that would match the HF 43430. Tried the book settings, then off-the-card stuff too, like 35 psi inlet, full fan, and low paint volumes to maximize atomization. The 43430 at 45 psi (at the gun, not the regulator), full fan, and 2 turns out on the needle would shoot slick enough to read the labels on the flourescent light bulbs across the room. However, the effective fan width is not more than 6" or so and I'd like to cover more per pass.
Got no axe to grind here; believe me, at $320 I want the Sata HVLP to work. Maybe it was a dumb buy. I tried a Sata 90-2 RP a few weeks ago. It was better, so I may see if my paint guy will swap and I'll try to fine tune an RP. Sata advice would be very welcome. Before the 43430 I shot everything with a Binks #7.
Painting
I suggest you open the paint volume on the Sata HVLP. I use 29psi at the gun handle and I get a 10 inch fan. Now you have to move fast! Also remember to **** your head at about 45 deg to the surface and look at the spray hitting the surface. Go real fast and go slower. You can see the difference between a dry and a wet coat. Go just slow enough to make your wet coat. If you start out too slow you will have sags and runs.
By the way it is easier to fix a run or sag then dry or orange peel.
Also an option on the orange peel is to sand most of the peel then clear coat (provided you have the technique mastered).
Ken
I suggest you open the paint volume on the Sata HVLP. I use 29psi at the gun handle and I get a 10 inch fan. Now you have to move fast! Also remember to **** your head at about 45 deg to the surface and look at the spray hitting the surface. Go real fast and go slower. You can see the difference between a dry and a wet coat. Go just slow enough to make your wet coat. If you start out too slow you will have sags and runs.
By the way it is easier to fix a run or sag then dry or orange peel.
Also an option on the orange peel is to sand most of the peel then clear coat (provided you have the technique mastered).
Ken
<<I suggest you open the paint volume on the Sata HVLP. I use 29psi at the gun handle and I get a 10 inch fan. Now you have to move fast! >>
Thanks Ken. Actually the above is the very first setup, three passes, fast, normal, and slow enough to force runs on the vertical panel. And I had already shot some small pieces (rudder bottom, trim tab), wasn't happy, and thus the test panel.
The fast pass was obviously too dry, a mist coat really, but that was the point; I was trying a "mist, wait, then shoot".
The normal pass was a "move fast" as you describe, sprayed almost heavy enough to run, with a glare light to see the contact surface. I like the application rate and fan width, but the as-sprayed surface texture wasn't all that great, per the previous small pieces. Fully filled, but distorted, not flat, maybe 1/8" between the highs, not the small nubby stuff of classic orange peel. After cure it checked at 1 mil with my thickness meter.
Flooded pass was a little flatter and flowed out, where it didn't sheet run and drip <g> About a 1-1/2 mil. You can get away with it spraying horizontal, but DCU2021 will bow up in a thick bead along the edges if you do, and edge work to correct it after is a pain. I think you can flood clear with any gun on a horizontal panel. I did a lot of that on previous parts. It works, but I was hoping for a thinner coat with better finish....thus the Sata purchase.
Your gun is also a 90-2 HVLP? Are you (or have you) sprayed high-solids clear like the PPG 2021 with it? Mine does pretty good on the pearl base coat, but that has less viscosity and I think less surface tension.
In any case, sure is nice to have somebody with the same gun. I appreciate the help.
Thanks Ken. Actually the above is the very first setup, three passes, fast, normal, and slow enough to force runs on the vertical panel. And I had already shot some small pieces (rudder bottom, trim tab), wasn't happy, and thus the test panel.
The fast pass was obviously too dry, a mist coat really, but that was the point; I was trying a "mist, wait, then shoot".
The normal pass was a "move fast" as you describe, sprayed almost heavy enough to run, with a glare light to see the contact surface. I like the application rate and fan width, but the as-sprayed surface texture wasn't all that great, per the previous small pieces. Fully filled, but distorted, not flat, maybe 1/8" between the highs, not the small nubby stuff of classic orange peel. After cure it checked at 1 mil with my thickness meter.
Flooded pass was a little flatter and flowed out, where it didn't sheet run and drip <g> About a 1-1/2 mil. You can get away with it spraying horizontal, but DCU2021 will bow up in a thick bead along the edges if you do, and edge work to correct it after is a pain. I think you can flood clear with any gun on a horizontal panel. I did a lot of that on previous parts. It works, but I was hoping for a thinner coat with better finish....thus the Sata purchase.
Your gun is also a 90-2 HVLP? Are you (or have you) sprayed high-solids clear like the PPG 2021 with it? Mine does pretty good on the pearl base coat, but that has less viscosity and I think less surface tension.
In any case, sure is nice to have somebody with the same gun. I appreciate the help.
Mike D
Well Known Member
Usually I am just lurking here sponging up information from you all in preparation for building. But finally here is a problem I have had a lot of experience with. So I will put my .02 in here.
The best tip I can give is to prevent runs or orange peel is to have a well lit area to paint in. Buy or borrow as many lights you need to be able to read the reflections as you are applying your paint. You are looking for even illumination. Take a look at a paint booth and see how they arrange the lights. (Both on the ceiling and walls) I like long fluorescent tubes because they linear reflections show warps and the start of runs. Sometimes I even use a portable 1? light to check problem areas. Color correct lights would be a great if you have the money.
Experts can substitute different reducers if they don?t have the correct temperature reducer but I would never recommend it until you have done quite a few jobs and know what you are doing. So, get the right reducer for the right temperature and use the correct amount. Use a reducing stick to measure with. If you over or under reduce it will affect your ability to achieve the correct flow and could affect the hardness and/or finish of the final result. Solvent popping and soft paint are not good. Also use the correct hardner if your paint system uses one. Too much hardner will make your paint soft when it dries. (I know that sounds backward but its not)
If you use a machine to sand out runs or orange peel be careful not to heat the metal too much or it can shrink the metal and cause warping. I recommend wet sanding (by hand) with 400 then 600 grit using a rubber sanding block. Then use a rubber squeegee to wipe off the water to see if the surface is smooth.
As for the application of paint, everyone has their own preferred settings but usually the key is to use the recommended pressure (per paint instructions) and the correct needle size. (you may need different sizes for primer and painting) Set your gun up so the trigger gives only air for the first ? of travel and then fades into more paint flow as you pull. I usually set my flow control to full on then back it off a turn or two. This will give me the ability to adjust the flow with the trigger as I paint. The air at the beginning eliminates sputter and allows for cleaning of the tip at the end of every pull. Rehearse your painting motions before you pull the trigger. This will let you know if you have enough reach to tie each stroke together (keep a wet edge and overlap your strokes) and let you plan where you will need to guide the hose so it does not hit the wet paint.
Sometimes drying paint on the gun's tip will restrict the flow and cause orange peel even with full trigger pull. Stop, take the tip off and clean it.
A good paint job is all about preparation. Degrease the part using one towel for application and one for wiping off the degreaser. Never let the degreaser dry on the part. (towel in each hand) Prime the part. Wet sand the part with 600 grit sandpaper, and paint within a day of sanding the primer. Degrease the primed part. Wipe with an anti-static dust cloth and then paint. Dont do extensive wet sanding in the booth. (contamination)
As for oil and/or water in the lines, I recommend having a filter (water trap) at the compressor and a disposable filter on the gun. This will solve the problems of condensation that may occur in the hose. You know you have a problem with contamination if you see fish eyes appear. If your compressor can keep up with your grinder it can keep up with your painting (larger tank is better).
Sorry for the long winded reply but hopefully I have helped someone here.
The best tip I can give is to prevent runs or orange peel is to have a well lit area to paint in. Buy or borrow as many lights you need to be able to read the reflections as you are applying your paint. You are looking for even illumination. Take a look at a paint booth and see how they arrange the lights. (Both on the ceiling and walls) I like long fluorescent tubes because they linear reflections show warps and the start of runs. Sometimes I even use a portable 1? light to check problem areas. Color correct lights would be a great if you have the money.
Experts can substitute different reducers if they don?t have the correct temperature reducer but I would never recommend it until you have done quite a few jobs and know what you are doing. So, get the right reducer for the right temperature and use the correct amount. Use a reducing stick to measure with. If you over or under reduce it will affect your ability to achieve the correct flow and could affect the hardness and/or finish of the final result. Solvent popping and soft paint are not good. Also use the correct hardner if your paint system uses one. Too much hardner will make your paint soft when it dries. (I know that sounds backward but its not)
If you use a machine to sand out runs or orange peel be careful not to heat the metal too much or it can shrink the metal and cause warping. I recommend wet sanding (by hand) with 400 then 600 grit using a rubber sanding block. Then use a rubber squeegee to wipe off the water to see if the surface is smooth.
As for the application of paint, everyone has their own preferred settings but usually the key is to use the recommended pressure (per paint instructions) and the correct needle size. (you may need different sizes for primer and painting) Set your gun up so the trigger gives only air for the first ? of travel and then fades into more paint flow as you pull. I usually set my flow control to full on then back it off a turn or two. This will give me the ability to adjust the flow with the trigger as I paint. The air at the beginning eliminates sputter and allows for cleaning of the tip at the end of every pull. Rehearse your painting motions before you pull the trigger. This will let you know if you have enough reach to tie each stroke together (keep a wet edge and overlap your strokes) and let you plan where you will need to guide the hose so it does not hit the wet paint.
Sometimes drying paint on the gun's tip will restrict the flow and cause orange peel even with full trigger pull. Stop, take the tip off and clean it.
A good paint job is all about preparation. Degrease the part using one towel for application and one for wiping off the degreaser. Never let the degreaser dry on the part. (towel in each hand) Prime the part. Wet sand the part with 600 grit sandpaper, and paint within a day of sanding the primer. Degrease the primed part. Wipe with an anti-static dust cloth and then paint. Dont do extensive wet sanding in the booth. (contamination)
As for oil and/or water in the lines, I recommend having a filter (water trap) at the compressor and a disposable filter on the gun. This will solve the problems of condensation that may occur in the hose. You know you have a problem with contamination if you see fish eyes appear. If your compressor can keep up with your grinder it can keep up with your painting (larger tank is better).
Sorry for the long winded reply but hopefully I have helped someone here.
Urethane paint
Good suggestions Mike. The key is seeing what you are laying down and to catch any holidays and fix them on the first pass. Sags and runs will have to wait.
Dan, follow the paint mfg instructions but as a general rule urethane paints should not be applied with a tack or mist coat. Usually 2 medium wet coats.
What you need to learn is what is a medium wet coat. That is why I suggest practicing by going from dry to wet. You will be able to see the difference. Start fast and slow down until you get that wet sheen. You can see it as it lays down. Remember to overlap 1/2 your fan. Once you get the feel it stays with you.
I open my paint flow, set a wide fan, and squeeze the trigger all the way and maintain a constant 6 to 8 inch distance above the surface. I have eliminated 4 variables. Now my only variable is speed. Control the speed control the application.
Ken
Good suggestions Mike. The key is seeing what you are laying down and to catch any holidays and fix them on the first pass. Sags and runs will have to wait.
Dan, follow the paint mfg instructions but as a general rule urethane paints should not be applied with a tack or mist coat. Usually 2 medium wet coats.
What you need to learn is what is a medium wet coat. That is why I suggest practicing by going from dry to wet. You will be able to see the difference. Start fast and slow down until you get that wet sheen. You can see it as it lays down. Remember to overlap 1/2 your fan. Once you get the feel it stays with you.
I open my paint flow, set a wide fan, and squeeze the trigger all the way and maintain a constant 6 to 8 inch distance above the surface. I have eliminated 4 variables. Now my only variable is speed. Control the speed control the application.
Ken
Thanks Ken and Mike.
Killing a few birds with one stone; here's a (sadly) typical surface as sprayed. Ignore the dirt specs, that's a different issue:
Not the nubby orange peel I think of as sprayed too dry. Sort of "irregular", wavy, not flat. Perhaps I'm just having a buildup problem, ie, the primer and base coats are not slick enough? Most of my past large panel painting experience was with Poly Fiber on fabric. That means everything was sanded with 400 wet a few times until just prior to color.
This is the other side of the part after machine sanding with 1500 Trizact, a little hard blocking with 2000 wet, and a few passes with a 1900 RPM buffer, white 3M pad, and 3000 grit 3M compound:
Jimmy, like the other guys said, you can fix it without stripping.
Killing a few birds with one stone; here's a (sadly) typical surface as sprayed. Ignore the dirt specs, that's a different issue:
Not the nubby orange peel I think of as sprayed too dry. Sort of "irregular", wavy, not flat. Perhaps I'm just having a buildup problem, ie, the primer and base coats are not slick enough? Most of my past large panel painting experience was with Poly Fiber on fabric. That means everything was sanded with 400 wet a few times until just prior to color.
This is the other side of the part after machine sanding with 1500 Trizact, a little hard blocking with 2000 wet, and a few passes with a 1900 RPM buffer, white 3M pad, and 3000 grit 3M compound:
Jimmy, like the other guys said, you can fix it without stripping.
Last edited:
Dan, you just showed what is great about this stuff. You can fix almost anything and end up with a show finish if you are willing to put in the time. I think we amateurs can look like professionals. The difference: they do it once, we do it several times. (sounds like building an airplane) But it is the results that count.
Ken
Ken
cytoxin
Well Known Member
first things first
1. if mine looked that good i would have left it.
2. you can sand out muuuuch worse than that.that level of orange peel could likely be sanded out of 2 coats. if its worse than you bettr have three coats on there to work with...watch the rivet heads.
3 dans photo looks like what your average new car finish looks like. i notice them all now at the red light while sitting in traffic. they have a fair amount of orange peel . the worst one ive seen yet was a nissan.
the trizact and the da are the ticket..as far as heating up the metal,,very unlikely, you would have to try pretty hard to do that and i dont think you could do it with 500+ paper especially wet\ on a DA
1. if mine looked that good i would have left it.
2. you can sand out muuuuch worse than that.that level of orange peel could likely be sanded out of 2 coats. if its worse than you bettr have three coats on there to work with...watch the rivet heads.
3 dans photo looks like what your average new car finish looks like. i notice them all now at the red light while sitting in traffic. they have a fair amount of orange peel . the worst one ive seen yet was a nissan.
the trizact and the da are the ticket..as far as heating up the metal,,very unlikely, you would have to try pretty hard to do that and i dont think you could do it with 500+ paper especially wet\ on a DA
Thanks Ken and Mike.
Killing a few birds with one stone; here's a (sadly) typical surface as sprayed. Ignore the dirt specs, that's a different issue:
Not the nubby orange peel I think of as sprayed too dry. Sort of "irregular", wavy, not flat. Perhaps I'm just having a buildup problem, ie, the primer and base coats are not slick enough? Most of my past large panel painting experience was with Poly Fiber on fabric. That means everything was sanded with 400 wet a few times until just prior to color.
This is the other side of the part after machine sanding with 1500 Trizact, a little hard blocking with 2000 wet, and a few passes with a 1900 RPM buffer, white 3M pad, and 3000 grit 3M compound:
Jimmy, like the other guys said, you can fix it without stripping.
Last edited:
Dan, thanks for the photos. The first shot is very similar to what I experienced on my second coat (except mine was a little more pronouced). So you think this was due to the substrate not being smooth enough? That could be, as I did very little light sanding on the previous coat (lightly hit it with 500 grit by hand just to knock off any surface contamination (grit). I know others on this thread have warned against over thinning, but I wonder if that would have helped the paint flow out better. I have ordered a new spray gun from Harbor Freight that is rated for 5 scfm, which is well within the flow capacity of my compressor. I am curious to see how it works on some test panels. If anyone else has any more experience or knowledge they can lend me, I do appreciate it.
Thanks again to all, Jimmy
Thanks again to all, Jimmy
cytoxin
Well Known Member
Jimmy, overthinning will mostly cause it run and apply less paint to the surface. if you want it to flow out, use a thinner for higher temps it dries slower and doesnt reduce the film build and allow the paint to flow.. this will also cause it to run if not done carefully. between each coat touch the paint on an ajacent taped surface and if it strings then wait until it doesnt before you apply the next coat.
in general if painting a small surface then use the correct temp thinner if doing a large surface use a range slower than the current conditions temp wise.
William,
<<you can sand out muuuuch worse than that.that level of orange peel could likely be sanded out of 2 coats. >>
Confirmed. This was in fact two coats.
<<.watch the rivet heads.>>
I sanded the bare metal with 120 on a firm Stickit pad. If there is a rivet head sitting .001 too high, it will show it. Beats finding a high rivet the hard way after paint.
<<.as far as heating up the metal,,very unlikely, you would have to try pretty hard to do that and i dont think you could do it with 500+ paper especially wet\ on a DA>>
100% agree. You can get it warm enough to oil can a little using the 120 dry, but it tightens up again when it cools 60 seconds later. You'll never get it hot enough to hurt it.
<<if you want it to flow out, use a thinner for higher temps it dries slower and doesnt reduce the film build >>
Agree again. I'm now using the 75-85F reducer at 70F, and at 80F I go to the 95F reducer. Learned it the hard way....shop temps shot up from 70 to 90 or so one morning. Got caught with the 75-85 stuff in the gun and it was a mess. Orange peel was bad, so I figured I'd just shoot an extra coat and sand the snot out of it with 600, then shoot again. What happened was that the surface flashed over before all the reducer trapped down in the paint could escape. I guess they call it solvent pop, but the effect was to form teeny tiny bubbles trapped like a bug in amber. Can't see them, but sanding opened them up. A respray showed a zillion pinhole pits, just like unsealed fiberglass. I stripped the panel and started over. Live and learn....use slow reducer, give it time to flash well between coats.
Jimmy,
<<So you think this was due to the substrate not being smooth enough?>>
Certainly not the aluminum. The DPLF epoxy primer has a 7 day respray window, so time for an experiment; I'll shoot primer, wait an day, block it wet, then spray base and color on a perfectly flat surface to see what I get.
<<you can sand out muuuuch worse than that.that level of orange peel could likely be sanded out of 2 coats. >>
Confirmed. This was in fact two coats.
<<.watch the rivet heads.>>
I sanded the bare metal with 120 on a firm Stickit pad. If there is a rivet head sitting .001 too high, it will show it. Beats finding a high rivet the hard way after paint.
<<.as far as heating up the metal,,very unlikely, you would have to try pretty hard to do that and i dont think you could do it with 500+ paper especially wet\ on a DA>>
100% agree. You can get it warm enough to oil can a little using the 120 dry, but it tightens up again when it cools 60 seconds later. You'll never get it hot enough to hurt it.
<<if you want it to flow out, use a thinner for higher temps it dries slower and doesnt reduce the film build >>
Agree again. I'm now using the 75-85F reducer at 70F, and at 80F I go to the 95F reducer. Learned it the hard way....shop temps shot up from 70 to 90 or so one morning. Got caught with the 75-85 stuff in the gun and it was a mess. Orange peel was bad, so I figured I'd just shoot an extra coat and sand the snot out of it with 600, then shoot again. What happened was that the surface flashed over before all the reducer trapped down in the paint could escape. I guess they call it solvent pop, but the effect was to form teeny tiny bubbles trapped like a bug in amber. Can't see them, but sanding opened them up. A respray showed a zillion pinhole pits, just like unsealed fiberglass. I stripped the panel and started over. Live and learn....use slow reducer, give it time to flash well between coats.
Jimmy,
<<So you think this was due to the substrate not being smooth enough?>>
Certainly not the aluminum. The DPLF epoxy primer has a 7 day respray window, so time for an experiment; I'll shoot primer, wait an day, block it wet, then spray base and color on a perfectly flat surface to see what I get.
Last edited:
Jimmy,
Results of the primer blocking experiment.
Two coats of DPLF (no reducer) indeed had some surface texture following an 18 hour cure (it would probably flow out better with the optional 1/2 part reducer addition). It is listed as a non-sanding primer because it is too gummy to sand dry, but it sands wet just fine. So, I blocked it with 600. I got an improvement in final as-sprayed finish, but I wouldn't call it a huge difference. Compare this photo with the previous post:
I conclude every little bit helps, but primer roughness doesn't seem to be the main factor in my own clearcoat orange peel result. Can't sand the intermediate base coats because they are metallics and pearls.
Following Mike's and Ken's suggestions, I paid particular attention to ensuring two full wet coats. Here you can see the telltale "wakes" around rivets, this on a rudder sprayed with the surface just off horizontal.
Also getting a run from time to time and some thick edges, and I've measured around a mil per pass on the test panel. I think I'm getting it on wet enough.
Maybe I should just stop worrying about it and rely on the cut and polish process. Got to get out the dirt nibs and stuff anyway. However, I sure would like to learn out how to shoot this stuff and get the glass look as-sprayed.
The "education and recreation" continues <g>
Results of the primer blocking experiment.
Two coats of DPLF (no reducer) indeed had some surface texture following an 18 hour cure (it would probably flow out better with the optional 1/2 part reducer addition). It is listed as a non-sanding primer because it is too gummy to sand dry, but it sands wet just fine. So, I blocked it with 600. I got an improvement in final as-sprayed finish, but I wouldn't call it a huge difference. Compare this photo with the previous post:
I conclude every little bit helps, but primer roughness doesn't seem to be the main factor in my own clearcoat orange peel result. Can't sand the intermediate base coats because they are metallics and pearls.
Following Mike's and Ken's suggestions, I paid particular attention to ensuring two full wet coats. Here you can see the telltale "wakes" around rivets, this on a rudder sprayed with the surface just off horizontal.
Also getting a run from time to time and some thick edges, and I've measured around a mil per pass on the test panel. I think I'm getting it on wet enough.
Maybe I should just stop worrying about it and rely on the cut and polish process. Got to get out the dirt nibs and stuff anyway. However, I sure would like to learn out how to shoot this stuff and get the glass look as-sprayed.
The "education and recreation" continues <g>
Spray vertical or horizontal?
If one has a choice, for example, wing or fuselage in a rotary device, is it preferable to spray a panel horizontal or vertical.
The advantages I see for vertical are ease of movement with the gun and hose, (therefore longer runs, easier to maintain distance from surface so the paint thickness is more unifrom) and possibly less contamination in the paint from anything floating in the air.
The disadvantage for vertical is increased likelihood of runs and sags.
I have painted quite a few cars and reshot the clear-coat on my Cherokee where there wasn't the option of surface orientation. I would like to hear from more experienced aircraft painters about their preference.
If one has a choice, for example, wing or fuselage in a rotary device, is it preferable to spray a panel horizontal or vertical.
The advantages I see for vertical are ease of movement with the gun and hose, (therefore longer runs, easier to maintain distance from surface so the paint thickness is more unifrom) and possibly less contamination in the paint from anything floating in the air.
The disadvantage for vertical is increased likelihood of runs and sags.
I have painted quite a few cars and reshot the clear-coat on my Cherokee where there wasn't the option of surface orientation. I would like to hear from more experienced aircraft painters about their preference.
