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Building Tips and technical articles. => Paint and finishing => Topic started by: wwwarbird on February 11, 2014, 12:48:41 PM
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I airbrushed some trim using a mask last night and I've run into some trouble.
This model has a silver basecoat with the maroon color directly on top of that. It's all Brodak dope from the wood up but I'm not placing any blame there, I've always had great results using it.
The model was prep sanded very well, wiped down with alcohol, and the maroon was sprayed two weeks ago. I started adding the cream trim color last night. Per my normal routine I typically remove any masking material as soon as the dope tacks up after spraying, 99% of the time without issue. This time, when I went to peel back the lettering masks, as soon as I got to the fresh paint edge it wanted to bring up the cream and maroon layer together, cleanly, right down to the silver base coat. This issue was all around the outer edges of the cream line, the freshly sprayed areas where the underlying maroon had been softened.
An odd thing here is that at the same time I also sprayed an adjacent stripe around the wing that was masked with a combination of Frogtape and 3M blue masking tape. There was no hint of trouble with those areas, I only had trouble with the paint mask edges I was using for the lettering. The attached photos show where I stopped taking the lettering mask off last night. I waited until today to take the rest of it up hoping to have better luck. Not to be, it acted exactly the same way today, even after drying overnight.
I still have a lot more trim work planned for this model but I'm kind of stuck here, or un-stuck I guess. ???
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Looks like a case of not enough thinner in the cream color. Also, silver is the hardest color to get to stick or to get anything to stick to. For me anyways.
Derek
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Looks like a case of not enough thinner in the cream color. Also, silver is the hardest color to get to stick or to get anything to stick to. For me anyways.
Derek
Thanks Derek. Any thoughts on why the trouble is only around the areas with the paint mask and not the tape? Maybe something to do with the paint mask material being slightly thicker that the tape?
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Wayne,
The trouble probably started with the prep of the silver. Knowing you were going to cover it with more paint plus probably a clear coat, you could have used a, not so fine, sandpaper. May have helped?
If I think I'll have trouble, that is, removing the mask sooner than I should, I lift, then cut with a #11 blade. This way, the mask can be removed flush and as though you are removing tape. Bits and pieces, takes longer, but sometimes it's worth it.
I'd like to see a photo of the entire wing half.
I have an idea for a possible fix.
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Since it is pulling the maroon off you may have not had enough thinner there as well.
Sticking to silver is such a PIA I don't do the silver anymore. That just adds to many issues just like this one. If you do it again the future make sure it is very clean before you put your next color on top. Dust sitting on top then paint on the dusty coat without enough thinner can cause what you have.
The masking material could be pulling it up as it has a much larger contact area compared to the tape.
I am not sure if you do this but heat the mask and tape with a hair dryer as you pull it off the model. DO NOT USE A HEAT GUN EVEN ON LOW!! Hair dryer only! I think this is your only method now as you are pretty far into your finish. Heat it up and go slow. It should be hot enough that the mask will get very soft as it comes up. You will certainly be able to tell the difference in the feel of the material when it is heated. You may want to do a test strip or two on your work bench to see what it feels like as it heats up. Fine line vinyl type tape will change as well when heated, it gets curly and just pulls right up with no issues. I never ever ever pull anything anymore without a hair dryer in hand.
Also when you pull make sure you are laying it back over the unpeeled area, like you are pulling it off at almost 180 degrees to itself. This makes a Sharp cutting edge as it pulls up. If you pull it straight up at 90 degrees to the surface it will take everything off to the covering...ask me how I know this.
Hope this helps.
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Since it is pulling the maroon off you may have not had enough thinner there as well.
After thinking about Derek's thinner response I was also thinking that maybe the maroon didn't have enough thinner in it either.
(BTW, not that it matters, but I never use silver as a base coat myself for many of the above reasons. Silver is definitely not a "friendly" color to work with. This one is not my airplane, I volunteered to take over and finish this project for a friend after the silver basecoat had already been applied.)
I get what you're saying Doug, but it's not the mask material pulling paint up, it's the fresh paint itself that's lifting. When you go to remove the mask it comes off of the maroon area without a problem, but then it starts lifting the cream that is fresh over the maroon as soon as you reach that edge line. It then pulls the cream/maroon layers off right down to the silver. I do always roll any masking material back against itself during removal, keeping it flat back against whichever surface it's on. While keeping it flat like that I'll also pull it in a direction away from the fresh paint line whenever possible. I've never tried it in a case such as this but I don't feel like warming things with a hair dryer would help any, but am I missing something with that?
Either way, I'm definitely going to add more thinner before the next trim session. I've also got another idea though...
I'm thinking of spraying the cream and then letting it dry completely. Then, before trying to remove the mask, sand carefully around the very edges of the mask outlines just enough to break or thin down the "connection" between the edge of mask and the new paint. It seems like if the paint wouldn't cling to the edge of the mask so much that I would be much better off. Maybe by weakening that "connection" I could sneak through this headache? I dunno, but I think it might be worth a try. ???
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well Wayne, to me it looks like the cream did not have enough thinner, or was sprayed to dry,, or it was to warm or the thinner was to fast not allowing it to melt into the silver,, do I understand the silver is also brodaks?
my theory would be that when you sprayed the next color on the cream, it allowed the thinner to penetrate just enough to break the bond with the silver,,
silver, especially with a high metallic silver, does not lend itself well to adhesion as there is a higher concentrate of solids ( the metal particles) than with typical dope,,
therefore its harder to get a good melt into it,,
silver is a carryover from full scale aviation where the silver is used as a barrier for UV since Dope has no UV protection and the UV would penetrate the dope and deteriorate the fabric covering,, it does serve some purpose for a sanding finishing guide to help see imperfections but I dont use it, a bright white and a strong lite casting across the surface is just as effective to me,,
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Thanks for the info Mark, more stuff to think about and it all makes sense. And yes, the silver is Brodak as is everything from the wood up.
Also, just to clarify with everyone here, the cream is the most recent color added in this equation. It's being sprayed directly over the maroon.
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You did not say how many coats of cream you applied. It sounds as if you went with one heavy coat and then tried to remove the mask. If so, try going with 3 very light coats, letting them dry between coats. The first will be just a "mist" coat. Multiple thin coats will get you the same coverage as one thick coat but with less paint build up, both on the wing and on the mask. It will be lighter and the mask should peel off cleanly. The lighter application also will not soften up the underlying coats as much. If that is what you did already, well, then, never mind. 8)
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Good points "Butch" and even more to consider. I did do it all in one nonstop session, going over and over it with the cream until I had the coverage I wanted. It was done with an airbrush so it did take a LOT of passes since it was over such a dark color. At the time I was thinking that by doing that it would get me the necessary "bite" all the way through. That obviously backfired on me this time. I do think more thinner would have helped but I'm mainly blaming the silver basecoat. Trying your suggestion might be another option, I'll keep it in mind.
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You have probably found out that Diana Cream is somewhat translucent and does not cover well. I would consider starting with a light coat of polar grey and white (50/50) over the maroon. If you want the cream to "Pop" follow it up with a light coat of pure white. Now you will be able to get good coverage with only 2 light coats of color. I usually thin at least 60% when using an airbrush, seems like a lot but I hate it when the brush clogs up.
Depending on the damage you may want to sand off the lettering, re-finish the damaged section, and try again. Been there, done that and I bet I'm not the only person on this forum who has had to go that route. HB~> 8)
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The Diana Cream could have been applied first, over a single coat of white primer.
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I've never tried it in a case such as this but I don't feel like warming things with a hair dryer would help any, but am I missing something with that?
Yes, the warming with the hair dryer will release the adhesive on the mask and tape. It pulls off with much less pulling needed from you. Think of a clean piece of tape stuck down to the table, and a dirty piece of tape stuck down. The dirty one lifts right up with alot less pulling than the clean one.
Any time you can lower the amount of adhesion of the tape and mask before removal you can lower your chances of the dreaded peel ups.
Try it on your bench and see what effect it has if any. I live/swear by it. I first learned it from a Windy video years ago. It is just more little trick to loosening the masks and tapes prior to what could be the peel ups that make your head spin!
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You can buy "low tack" tape used for drafting.
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(snip) I do think more thinner would have helped but I'm mainly blaming the silver basecoat. (snip)
Hi Wayne,
I quit using silver as a basecoat several years ago, mainly for the problems you experienced. I know Windy swore by it, but that was for the ability of it to show any imperfections in the substrate. He really had a system worked out and it worked for him. It also is horrible to use a basecoat of yellow or similar. You get that great "puke" green color Randy P. loves so much! LL!
It DOES delaminate easier than any other color.
Bill
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You can buy "low tack" tape used for drafting.
You don't get the same sharp edge and if you need to leave it on there for a while and apply other colors it can easily start to pull up on its own with the shrinking paint that is now on top of the tape. I have tried it...for me it was no bueno.
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Yes, the warming with the hair dryer will release the adhesive on the mask and tape. It pulls off with much less pulling needed from you. Think of a clean piece of tape stuck down to the table, and a dirty piece of tape stuck down. The dirty one lifts right up with alot less pulling than the clean one.
Any time you can lower the amount of adhesion of the tape and mask before removal you can lower your chances of the dreaded peel ups.
Try it on your bench and see what effect it has if any. I live/swear by it. I first learned it from a Windy video years ago. It is just more little trick to loosening the masks and tapes prior to what could be the peel ups that make your head spin!
Thanks Doug, but did you catch this in Reply #5...?
My own quote: I get what you're saying Doug, but it's not the mask material pulling paint up, it's the fresh paint itself that's lifting. When you go to remove the mask it comes off of the maroon area without a problem, but then it starts lifting the cream that is fresh over the maroon as soon as you reach that edge line. It then pulls the cream/maroon layers off right down to the silver.
Softening the mask adhesion with heat makes sense, but that's not my problem here.
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I've also got another idea though...
I'm thinking of spraying the cream and then letting it dry completely. Then, before trying to remove the mask, sand carefully around the very edges of the mask outlines just enough to break or thin down the "connection" between the edge of mask and the new paint. It seems like if the paint wouldn't cling to the edge of the mask so much that I would be much better off. Maybe by weakening that "connection" I could sneak through this headache? I dunno, but I think it might be worth a try. ???
I have used this technique and it does work. It is rather tedious but it will save your a$$ sometimes.
I like the look of silver and I have used it quite a bit on my planes but it does take some skills that are only acquired buy making the mistakes yourself. Once you have it all figured out you will only make a few mistakes. HB~>
Someone said to sand the silver, not sure who but it is a BAD idea. You will not see the mess you created until you shoot final clear, then you will be able to see every sanding scratch that you put in the silver. It will almost turn black. Now this is a very effective technique if you are going for a weathered look on a scale type plane...
Derek
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Thanks Derek. Any thoughts on why the trouble is only around the areas with the paint mask and not the tape? Maybe something to do with the paint mask material being slightly thicker that the tape?
It could be a number of things including maybe you just got lucky with the tape areas.
Derek
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Thanks Doug, but did you catch this in Reply #5...?
My own quote: I get what you're saying Doug, but it's not the mask material pulling paint up, it's the fresh paint itself that's lifting. When you go to remove the mask it comes off of the maroon area without a problem, but then it starts lifting the cream that is fresh over the maroon as soon as you reach that edge line. It then pulls the cream/maroon layers off right down to the silver.
Softening the mask adhesion with heat makes sense, but that's not my problem here.
I see what you are saying. I have had that too. Could be not enough thinner as suggested earlier so it is thick and drying to the edge of the mask with more adhesion than it does to the paint. That sounds about right?
Look like you will be on it with the #11 for a while to get it off. Just a scar from the should be enough to get it to separate from the mask edge. Next time by with the cream just a bit more thinner and go slow on removal.
I am curious to see how it goes. Keep us posted.
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I remembered that I had this problem (same as Wayne's) when I used too hot of a thinner and added retarder (very humid). Made the trim paint TOO hot and melted to the basecoat. The trim came off, but the basecoat around it was fine. If I had left it alone longer it would have been fine.
BIG Bear
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I have used this technique and it does work. It is rather tedious but it will save your a$$ sometimes.
Derek
Saving my a$$ is my objective here. ;D
Thanks for the thoughts and ideas guys. Scribing the edge with a #11 might be a consideration too, I never thought of that. I'm gonna start with more thinner and we'll see how things pan out...
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Looks like a case of not enough thinner in the cream color.
Derek
Well, I made some positive progress tonight. ;D ;D ;D
Derek nailed it, apparently I just needed more thinner. After scratching my head for the past week I got a chance to attack it again tonight and try doing the outboard wing stripe and graphic. After staring at it all long enough and thinking about everything I just felt like more thinner would probably do the trick. I roughly doubled the amount that I already had in there and then shot it good and wet with the airbrush, all in one session again. As soon as it tacked up I peeled everything off and it came out perfect. Thinking back about that first session, I did use a bit less thinner than I normally would have. At the time I was thinking the cream would cover better that way but it actually seemed to cover better this time around, with more thinner. That's what I get for thinking. HB~>
I'll post some pics when I get further along. Thanks for the help!
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Well, I made some positive progress tonight. ;D ;D ;D
Derek nailed it, apparently I just needed more thinner. After scratching my head for the past week I got a chance to attack it again tonight and try doing the outboard wing stripe and graphic. After staring at it all long enough and thinking about everything I just felt like more thinner would probably do the trick. I roughly doubled the amount that I already had in there and then shot it good and wet with the airbrush, all in one session again. As soon as it tacked up I peeled everything off and it came out perfect. Thinking back about that first session, I did use a bit less thinner than I normally would have. At the time I was thinking the cream would cover better that way but it actually seemed to cover better this time around, with more thinner. That's what I get for thinking. HB~>
I'll post some pics when I get further along. Thanks for the help!
Thanks Wayne,
I have learned a lot from my mistakes and I make plenty of mistakes. Its knowing how to fix them that is the key!
Derek
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On my old Dreadnought I had a couple of small spots where the same thing tried to happen. I used a #11 blade and went around the edge of the mask very lightly. You don't need a deep cut, just a light score to give the paint/mask edge a place to "break" as you lift.
If you posted this problem on one of the scale plastic model forums, they would come back saying the root (besides using silver) is from too heavy a coat of paint, instead of many ultra light coats. The heavy coats "bridge" the interface between the surface and the mask and that lets the mask lever the coat right off.
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Well things have been going much better since I added more thinner to the cream color. Still kicking my own a__ for that mistake. I've got the lettering sanded and touched up pretty well from that initial train wreck, good enough that the bad spots should all but disappear with the final clearcoats. I've got all of the other trim done now too except for adding some stripes yet on the stab and elevator. Just have to do those and the "canopy" and I should have it whipped. Photos still to come...
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Well things have been going much better since I added more thinner to the cream color. Still kicking my own a__ for that mistake. I've got the lettering sanded and touched up pretty well from that initial train wreck, good enough that the bad spots should all but disappear with the final clearcoats. I've got all of the other trim done now too except for adding some stripes yet on the stab and elevator. Just have to do those and the "canopy" and I should have it whipped. Photos still to come...
That's good to hear Wayne. Cant wait to see some pictures.
Derek
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That's good news!!!
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Well, here's where I ended up...
With a lot of breath holding and nail biting I was able to finally get through the rest of the trim work. I fought a lot of various issues with this one in addition to the original "lift" problem in this post. Even as simple as this scheme is I don't think I've ever had such a hassle getting through a paint job. I won't explain the multiple train wrecks but it was a one step forward, two or three or four steps back all the way through. HB~>
Anyway, I'm not overly happy with the result but it is what it is and it's time to "abandon" the finish on this one. At this point I'm proclaiming it ready for clear, with my fingers crossed that nothing else pops up, literally...
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BTW, the "HotShot" is a mostly scratchbuilt original design built around a Brodak ARC P-40 wing. The idea was for the overall look of a '30's style racer or sport plane. That's also why I chose the Maroon and Cream color scheme, to help achieve the period look.
As far as the airframe goes only the main ARC wing itself was used, without the original kit flaps. Everything else was simply sketched out and done from scratch. It will be powered with a Saito .56, oomph shouldn't be a problem. ;D
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I like it Wayne,, its classy and different,, the colors do add to the golden era feel too,,
looking forward to flight reports,,
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Wayne,
I agree with Mark. I think you did a fine job with the model, even considering those issues.
The model"s appearance certainly remind me of the Globe Swift aircraft, which I happen to have time in.
It's a good looker!
Makes me want to finish a model!
Charles
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I like it Wayne,, its classy and different,, the colors do add to the golden era feel too,,
looking forward to flight reports,,
Thanks Mark, I always figure one less white plane at the field can be refreshing. ;D
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While you might not be happy with it, I think it's an amazing recovery, and the final product is beautiful.
The colours and scheme give it a very Rearwin look.
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Wow!
Love the wing graphics!!
Marcus