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Thread: Paint and/or dope dope repair

  1. #1

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    Paint and/or dope dope repair

    Hi everyone,
    I'm new to this forum and a new supercub owner!
    There's one problem: My 1976 pa18-150 has original paint that is tired.
    I am looking for advice on how to fix cracks in paint, large areas peeling up exposing fabric etc. I've read all over and cannot find specific information on this.

    Pictures will follow

    Thanks!

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  3. #3
    phdigger123's Avatar
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    Well….. With original fabric from 1976 I would be concerned about what is underneath the fabric. Where was this airplane living for the last 46 years? Has it been hangared? You may have some serious corrosion in the rear door tube and/or the lower longerons. You may be looking at a full re-cover.

  4. #4
    S2D's Avatar
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    Acetone is your friend.
    Use lots of it on a rag to blend the stuff back in then redope the areas
    Looks like you have a metal belly so a good inspection of the tubing shouldn't be a problem.
    AFNB

  5. #5
    behindpropellers's Avatar
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    Quote Originally Posted by S2D View Post
    Acetone is your friend.
    Use lots of it on a rag to blend the stuff back in then redope the areas
    Looks like you have a metal belly so a good inspection of the tubing shouldn't be a problem.
    The door post tube though....

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    Quote Originally Posted by behindpropellers View Post
    The door post tube though....
    Which tube are you refering to?
    The tube that is part of the door or part of the frame the door sits in?

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    Quote Originally Posted by phdigger123 View Post
    Well….. With original fabric from 1976 I would be concerned about what is underneath the fabric. Where was this airplane living for the last 46 years? Has it been hangared? You may have some serious corrosion in the rear door tube and/or the lower longerons. You may be looking at a full re-cover.

    Thx for the insight.
    It has been hangared all its life in dry land.
    The frame looks perfect and so does the fabric from the inside of the tail! (no light spots)

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    What do you mean by redope the areas?
    Use the acetone to melt the paint back together and then dope it? I always thought it went dope and then paint in that order.
    What about the areas that the paint is peeling back in sheets? Can that be melted back on with acetone? Or repainted and blended?

    Thanks for the help!

    My apologies for my cluelessness.

  9. #9
    S2D's Avatar
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    First off forget the word paint. If your plane is original like it looks, you have dope on it .
    Nitrate dope then clear dope then silver dope then white dope.
    When you start rubbing that acetone in,bit will all mix together. Rub it til the edges are feathered. You really can't screw it up if it's dope.
    Now someone might have gotten lazy and sprayed some enamel paint on some of those repairs.
    They will be a little harder to get that enamel off before the dope starts blending together.
    Once you get an area feathered, you start building it up with dope. Clear, silver then white. Or skip the clear. Skip the nitrate too.

    On the bigger areas that have started to peel, go ahead and get rid of the loose piece, feather the edges and build back up with dope, not paint.

    Lot of elbow grease but not real expensive to buy some time before you have to recover.
    .
    AFNB
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  10. #10
    S2D's Avatar
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    Quote Originally Posted by behindpropellers View Post
    The door post tube though....
    Small drill and ice pick will answer that question.
    If the ice pick goes thru the tube, get someone competent to repair it.
    AFNB
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  11. #11
    S2D's Avatar
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    Best advice would be to find a good super cub mechanic that can look it over and advise you on what to do.
    Where are you located
    AFNB
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  12. #12

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    Talking

    Quote Originally Posted by S2D View Post
    First off forget the word paint. If your plane is original like it looks, you have dope on it .
    Nitrate dope then clear dope then silver dope then white dope.
    When you start rubbing that acetone in,bit will all mix together. Rub it til the edges are feathered. You really can't screw it up if it's dope.
    Now someone might have gotten lazy and sprayed some enamel paint on some of those repairs.
    They will be a little harder to get that enamel off before the dope starts blending together.
    Once you get an area feathered, you start building it up with dope. Clear, silver then white. Or skip the clear. Skip the nitrate too.

    On the bigger areas that have started to peel, go ahead and get rid of the loose piece, feather the edges and build back up with dope, not paint.

    Lot of elbow grease but not real expensive to buy some time before you have to recover.
    .
    Thanks for the tips!
    I will get some acetone and order some dope this weekend. Is there much difference between clear, silver, and white dope? Is the white UV resistant?
    I am in the Colorado plains area and have a decent mechanic sorted but not a supercub guy

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    What is the best brand to get for dope?

  14. #14
    skywagon8a's Avatar
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    Quote Originally Posted by Maxr View Post
    Thanks for the tips!
    I will get some acetone and order some dope this weekend. Is there much difference between clear, silver, and white dope? Is the white UV resistant?
    I am in the Colorado plains area and have a decent mechanic sorted but not a supercub guy
    Quote Originally Posted by Maxr View Post
    What is the best brand to get for dope?
    You had better sit down with that mechanic to learn from his advise. He SHOULD know fabric. If he doesn't, find another mechanic. Performing dope and fabric work is not difficult but does require an understanding of the process.

    Also Nitrate dope sticks down better than Butyrate. Butyrate fills better than Nitrate, thus takes fewer coats to finish.
    N1PA
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  15. #15
    Steve Pierce's Avatar
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    Door frame rust. https://www.supercub.org/forum/showt...oor-Frame-Rust
    You have 46 year old Ceconite and butyrate dope that has dried up and cracked. It has poor adhesion anyway. Download the Ceconite manual here. https://www.conaircraft.com/download-manuals
    You can take a blow gun and plastic scraper and remove most all of the finish and then re-coat. Just know you are starting a snowball.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  16. #16
    supercrow's Avatar
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    Quote Originally Posted by Steve Pierce View Post
    Door frame rust. https://www.supercub.org/forum/showt...oor-Frame-Rust
    You have 46 year old Ceconite and butyrate dope that has dried up and cracked. It has poor adhesion anyway. Download the Ceconite manual here. https://www.conaircraft.com/download-manuals
    You can take a blow gun and plastic scraper and remove most all of the finish and then re-coat. Just know you are starting a snowball.
    Agreed Steve Easier to cover that one then freak with it. And fix whatever else needs to be done after nearly 50 years old
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  17. #17
    S2D's Avatar
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    Quote Originally Posted by Maxr View Post
    Thanks for the tips!
    I will get some acetone and order some dope this weekend. Is there much difference between clear, silver, and white dope? Is the white UV resistant?
    I am in the Colorado plains area and have a decent mechanic sorted but not a supercub guy
    Only the silver is uv resistant.

    Somewhere on this site are some videos Steve Pierce and SJ made that go into great detail of how to maintain your airplane watch them and get you mechanic to watch them too.

    You are going to find there are mechanics that can
    1. Keep an old Super Cub flying for a long time
    2. Turn a Super Cub into a $150,000.00 piece of art.
    Some can do both, some can't do either.
    Make sure yours can at least do #1.
    Last edited by S2D; 11-02-2022 at 07:36 AM.

  18. #18
    pittsdriver's Avatar
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    Hate to tell you this but this is too far gone to re paint. You have several places that are down to the fabric. You might consult the Consolidated Coatings manual. The finish can be rejuvenated but that can only fix small cracks. DON'T use acetone. The first layer on the fabric is Nitrate. It soaks into the weave and gives a good base for the Butyrate to adhere to. Usually there is about three coats of Nitrate with the first coat brushed on. Following that is around three coats of silver Butyrate sprayed on and sanded between coats followed by the color coats of Butyrate. Even if you are just going for a re spray the airplane should be disassembled. If you go that far it really is time for a re cover. There are several fabric systems out there that are much better than dope and will last almost forever. I have used all of the systems and have settled on Airtech as the best. As for cost a re fabric job will cost over $30,000. Just the materials are now $8500. I just happen to be in the middle of a Cub re cover and I have done 6 Supercubs in the last few years.
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  19. #19
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    Just to save on confusion for anyone coming across this thread in the future, I thought I'd clarify the use acetone, don't use acetone discrepancy.

    I believe Mr. Pitts thinks you are going to respray the whole plane with paint or dope. If that were the case he is 100% right. You'd probably be wasting your time, altho it still could be done, just pointless.

    If you are talking about just fixing a few problem areas, Acetone works just fine to feather the dope. ( butyrate thinner also works, just a little slower and more costly to ship) Acetone can be picked up at any hardware store.

    So I took a couple pictures.
    The first is of an area that the dope peeled away from,that has been cleaned up.
    The second is a lint free rag saturated with acetone. (gloves are highly recommended)
    The third is after a little elbow grease is applied. (I probably did an area larger than needed)

    It is now ready to start building back up with dope.
    AFNB
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    It should not be that hard to fix what you have. Do find a local fabric guy and bring some beer or bottle of his/her choice. Clean up the loose stuff like S2D says and stop at silver. Ya can add some white if you want but silver does fine for a while. Seems to me one of our respected wrench turners had a bit of silver on his cub!! I would agree it will need a recover sooner than later but for a new cub driver with unknown tailwheel hours that may come much sooner than latter. I did lots of touch up on my first plane with MEK blending, silver, and bottom of an old can of paint my IA had. Sold the plane to Don Lee as a trainer and sure enough it picked up some new fabric over the years. If it is a stock cub you will be getting MOREBETTERDISEASE. When you figure out all the changes you need that is the time to do fabric. Just go fly for 3-4 years and then see what ya want. DENNY
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  21. #21
    BC12D-4-85's Avatar
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    Fix the obvious spots and fly the rest or sell the problem if it bothers. New to old they still fly the same.

    Gary
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  22. #22

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    Quote Originally Posted by pittsdriver View Post
    Hate to tell you this but this is too far gone to re paint. You have several places that are down to the fabric. You might consult the Consolidated Coatings manual. The finish can be rejuvenated but that can only fix small cracks. DON'T use acetone. The first layer on the fabric is Nitrate. It soaks into the weave and gives a good base for the Butyrate to adhere to. Usually there is about three coats of Nitrate with the first coat brushed on. Following that is around three coats of silver Butyrate sprayed on and sanded between coats followed by the color coats of Butyrate. Even if you are just going for a re spray the airplane should be disassembled. If you go that far it really is time for a re cover. There are several fabric systems out there that are much better than dope and will last almost forever. I have used all of the systems and have settled on Airtech as the best. As for cost a re fabric job will cost over $30,000. Just the materials are now $8500. I just happen to be in the middle of a Cub re cover and I have done 6 Supercubs in the last few years.

    Thanks for the input pittsdriver.
    Keep in mind that I have shown only the worst spots of the dope. The rest of the plane looks great. I am curious why you say not to use acetone though.
    Supercubs are made to be used, if i put $30k into new covering I wouldn't fly it the way it is meant to be flown
    Maybe sometime in the future but not today. I am confident I could go fly it across the country today just fine...it may even feel off some dope for me
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  23. #23

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    Thank you for the pics.I will be doing that very soon. The left side of my cub looks so bad because I had a small gas leak that de-laminated the dope (previous owners fault). This has since been fixed with brand new gas lines. The rest of the covering is great. I believe that if i touch up these areas I will be ready to fly for quite sometime and will probably redo it all in the future.

  24. #24

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    Quote Originally Posted by DENNY View Post
    It should not be that hard to fix what you have. Do find a local fabric guy and bring some beer or bottle of his/her choice. Clean up the loose stuff like S2D says and stop at silver. Ya can add some white if you want but silver does fine for a while. Seems to me one of our respected wrench turners had a bit of silver on his cub!! I would agree it will need a recover sooner than later but for a new cub driver with unknown tailwheel hours that may come much sooner than latter. I did lots of touch up on my first plane with MEK blending, silver, and bottom of an old can of paint my IA had. Sold the plane to Don Lee as a trainer and sure enough it picked up some new fabric over the years. If it is a stock cub you will be getting MOREBETTERDISEASE. When you figure out all the changes you need that is the time to do fabric. Just go fly for 3-4 years and then see what ya want. DENNY

    I agree Denny, fix the small areas to make it flyable and get some time under my belt. Recover years down the road and get some float fittings and other goodies installed
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  25. #25
    pittsdriver's Avatar
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    Quote Originally Posted by Maxr View Post
    I agree Denny, fix the small areas to make it flyable and get some time under my belt. Recover years down the road and get some float fittings and other goodies installed
    If you go to the Randolph website and download the manual it tells how to make repairs and re paint. They specifically say to use butyrate thinner to soften up and remove outer layers. I put a baggage door on a Scout and had to strip the dope down to the fabric to attach it around the door opening and tape. Worked great. I would just patch everything then and would not go to the work to re spray the whole airplane. Make sure the finish is in fact dope and not something like polyurethane.
    Vans RV7 finished 2008
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