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Thread: Is there a safe media blasting material for paint removal on composite?

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    Registered User JamesAero's Avatar
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    Is there a safe media blasting material for paint removal on composite?

    I know the first choice for most people is sanding. Some people have suggested there are safe chemical strippers, but I don't trust that. Another alternative to sanding would be media blasting. Several sites have products listed as safe for fiberglass. I'm pretty sure they are referring to Corvettes and boats though. At the softer end of abrasives there is baking soda and plastic bead. The mid-range would be glass bead and the real rough stuff would be sand. Has anyone tried soda or plastic bead blasting to remove paint from an epoxy fiberglassed aircraft? Are there any educated opinions if not?

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    Registered User Tom Nalevanko's Avatar
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    Re: Is there a safe media blasting material for paint removal on composite?

    Baking soda seems to work well. Here is the start of work on the nose cowl of a 1977 Cessna 182. It certainly does the job that would be difficult to do by hand sanding. You can see some of the Cessna 77 ugly yellow underlying paint in the picture.

    I am still experimenting as the effort is a bit tedious. Next is to use a more coarse Soda; all available at Harbor Freight.
    Attached Thumbnails Attached Thumbnails Is there a safe media blasting material for paint removal on composite?-img_0151.jpeg  

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    Moderator Topaz's Avatar
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    Re: Is there a safe media blasting material for paint removal on composite?

    There's a dry-ice blasting process that might be good. Leaves no blasting media on the part at all, since it simply evaporates. The media is fairly "soft" as well.
    Last edited by Topaz; November 15th, 2010 at 12:46 PM.
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    Registered User BBerson's Avatar
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    Re: Is there a safe media blasting material for paint removal on composite?

    It takes a huge compressor to work any faster than sanding. A major investment just for an occasional composite aircraft.

    I tried paint stripper on nonstructural fairings. It works if you clean it off quickly before it attacks the epoxy. But some of the epoxy comes off anyway and requires rework. Sanding is usually the best for large surfaces.

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    Registered User JamesAero's Avatar
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    Re: Is there a safe media blasting material for paint removal on composite?

    Tom, what type of delivery system are you using? Your progress looks great so far.

    Topaz, I was interested in the dry ice blasting process as well. I think the cost would be discouraging though.

    BBerson, I could see using paint stripper on nonstructural items. Too bad the whole plane needs to be re-painted.

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    Moderator Topaz's Avatar
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    Re: Is there a safe media blasting material for paint removal on composite?

    Quote Originally Posted by JamesAero View Post
    ...Topaz, I was interested in the dry ice blasting process as well. I think the cost would be discouraging though.....
    Unless you plan on doing this a lot, I'd find a vendor and have them strip the part for you. Even if that's twice what having someone sand-blast it for you, we're still talking fairly low cost, compared to your time spent hand-sanding. I don't think purchasing a piece of equipment like this makes any kind of sense for an occasional use. By the time you took delivery and got yourself trained up, you could've hand-sanded the part twice over.

    Just out of curiosity, why do you need composites stripped of paint?
    "If you have built castles in the air, your work need not be lost; that is where they should be. Now put the foundations under them." - Henry James Thoreau

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    Registered User JamesAero's Avatar
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    Re: Is there a safe media blasting material for paint removal on composite?

    I'm checking into that as well. There is a place in Portland that could probably do it. They listed stripping the exterior of a Corvette for $600-$900 on their website. Sandpaper sounds a lot more attractive at those prices.

    The reason I'm looking into this is I bought a partially completed Star-Lite a few days ago. It wasn't ready for paint, the paint job is poor quality, and I don't want a yellow airplane. I guess I could sand it down partially, fill, prime and paint over the existing paint. I can't imagine the paint would weigh that much on a small single seat airplane.

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    Registered User wsimpso1's Avatar
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    Re: Is there a safe media blasting material for paint removal on composite?

    The LongEZ/Cozy folks talk about sandblasting (low pressure) and soda blasting to prep their surfaces for application of microballoon fairing compounds. Search on those keywords and see what you can find.

    Billski

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    Registered User Tom Nalevanko's Avatar
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    Re: Is there a safe media blasting material for paint removal on composite?

    I just use a shop compressor and a cheap Harbor Freight 15 lb. soda blaster. It works well although it is tedious and, in retrospect, a 40 lb. blaster would minimize the fillups. Makes a big mess too but I do it over a big box on a tarp outside the hangar and power wash anything that gets on the ground. Have been using the Medium blast media but will try the Extra Large one to see if there is any improvement. Supposedly this will not harm plexi so it can be used right next to a windshield. But I will test this first with some scrap pieces. Will keep you all updated.

    I don't think that this level of equipment is practical for a whole aircraft. I am doing it on a Cessna 182 that only has limited composite areas. But I do plan on using it on the aluminum in delicate areas.

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    Registered User BBerson's Avatar
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    Re: Is there a safe media blasting material for paint removal on composite?

    Quote Originally Posted by JamesAero View Post
    I guess I could sand it down partially, fill, prime and paint over the existing paint. I can't imagine the paint would weigh that much on a small single seat airplane.
    Correct.
    The paint only needs to be removed if cracked or peeling.
    But, if the weight is still a concern(such as control balance), then sand most of it off, but leave enough to allow a good form.
    Improper sanding will make it worse. Use proper sanding technique to maintain a good form.

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    Registered User Tom Nalevanko's Avatar
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    Re: Is there a safe media blasting material for paint removal on composite?

    Also look carefully for raised spots, blisters or 'bubbles' and knock these down. That's my main problem on my Cessna composite. I am taking it down to the bare fiberglass and will use epoxy/microballoons to give it a really good finish and then prime and paint for a worldclass shine.

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    Registered User JamesAero's Avatar
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    Re: Is there a safe media blasting material for paint removal on composite?

    Thanks for the suggestions everyone! I have tomorrow off, so I'll take the time to try sanding down a few areas before purchasing any more equipment. Hopefully it will not be as bad as I fear.

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    Re: Is there a safe media blasting material for paint removal on composite?

    Ground nutshell works nice and won't harm anything but the paint.

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    Registered User JamesAero's Avatar
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    Re: Is there a safe media blasting material for paint removal on composite?

    Here is an update if anyone is interested. I've tried sanding, soda blasting, and a chemical stripper. They all work well for different areas, but I would say none work well for all areas.

    The chemical stripper I used was E-Z Way Stripper. It worked as advertised, but the top layer of glass seemed a little soft until it completely dried. I only used it on an inspection panel and I'm still hesitant to use it on anything structural at this point. It would be great for tight areas that can't be sanded though.

    The Soda Blaster works fast, but the one I used had a small nozzle and doing a large surface would take forever. It also took the epoxy off down to the first layer of glass. Luckily this was tested on the inspection panel as well. I might have had too much pressure though. It could be used for tight areas too.

    Sanding has been the best method. I purchased an electric random orbital sander from Harbor Freight for about $20 and it has been a tremendous help. I also bought some Dura-Blocks for hand sanding and they work well too. Sanding seems to give me the best control over the end result. I wish there was a faster and easier way to do this, but it looks like elbow grease is best way for me to make this turn out well.

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    Registered User Tom Nalevanko's Avatar
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    Re: Is there a safe media blasting material for paint removal on composite?

    I just blasted 100 lbs. of the XL size soda from Harbor Freight today and finished the composite section of my Cessna top cowl. The larger size works much better on composite than the Medium size. Soda blasting is tedious but I don't think that sanding would have been any quicker or would have had really good results.

    I also blasted some fiberglass pieces that were on my nose canard. This worked well. See pix; the tools are in the pix to keep the pieces from blowing away. I will rework these like new. The alternative was to buy these new for the jaw dropping price of $900! Eek.

    I really doubt that the soda blast is removing resin and going down to the fabric. The resin is fairly hard and the soda is relatively pretty soft. What might be removed is a micro-slurry or equivalent on the fiberglass used to fill low spots.
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