removing glue from plastic....

Discussion in 'Scratchin' & Bashin'' started by stary, Dec 17, 2003.

  1. stary

    stary Member

    I read, either here or on another forum, that you can do this by soaking the part or parts in either boiling water, or pine-sol. But, how long do you soak them for?
    Would rubbing alcohol from the drugstore also work? The structure (a WALTHERS bridge) is not painted, and the parts are already apart.
    I'm talking about the plastic solvent glue, from TESTORS.:confused:
  2. ezdays

    ezdays Out AZ way

    Testors is not a glue, it actually melts the plastic and forms a weld with the second piece. It evaporates quickly. The thicker solvent-based "glue" is actually the same solvent in a thick base that helps it bridge gaps and holds the two pieces together while the solvent does its thing. If the pieces are apart and it looks like there is glue on them, it is really deformed plastic. Unless someone knows of another way, as far as I'm concerned, the only way you can get rid of it is to sand or file.

  3. MasonJar

    MasonJar It's not rocket surgery

    If a solvent type glue is used there is no "glue" to remove. The joint is actually made of a small amount of each part that was melted by the solvent.

    You have two options. One is to cut the pieces apart at the joint, and then file or sand the pieces back to near original condition, as Don suggested.

    The other way is to apply more solvent glue, which will weaken the joint so it can be pulled apart. There are two problems (challenges?) with this - 1) You may damage a part of the piece, like the outside face, or small details as the plastic is softened by the solvent, and 2) you will have to wait until everything hardens, because you will have to sand/file it anyway.

    Hope that helps...

  4. Fred_M

    Fred_M Guest

    And add; the methods you mention, pinesol, rubbing alky are paint removal pratices. Boiling water is to soften plastic to bend it and is usually destructive to the pieces of a kit. It's also dangerous for the burns that can result. My fingers are still healing from a hotmelt glue accident last week. DASH
  5. jon-monon

    jon-monon Active Member

    If you have a lot to remove, you might employ a sander. Have to be very careful with a little drum sander on a dremel. Maybe a jitterbug or belt sander upside down in a vice, unless you have some sort of bench sander.

    I watched that episode a couple of nights ago. The last M*A*S*H as far as many are concerned.
  6. MasonJar

    MasonJar It's not rocket surgery

    Sorry - I realized after reading Jon's message, and going back to your original, that the pieces are already apart.

    However, the same info applies - there is no glue to remove. The spot that appears to have glue is actually the platic itself, distorted by being softened by the solvent. It has then hardened into a "not as it originally was" shape.

    You can sand or file, but if the area is really bad, you might try a chisel blade in your Xacto knife - use it to get most of the really rough stuff off before sanding with fine sandpaper.

  7. TrainClown

    TrainClown Member

    The Best Way To Remove Plastic

    What ever works for you. I guess.

    I do not like to sand plastic, unless I need to absolutely smooth out the surface for paint. I find it is too dusty when you have to remove a lot of material and shape a piece. And when I try to sand one spot I wind up sanding all the area around the spot too, and this distorts the surface. Filing works good if you have a file to fit the space you need to shape, and if it is sharp enough not to tear the plastic. I usually file stuff to align it and make it fit square.

    What I find to be a better way is to carve off the offending bits of plastic. I have a pocket knife that I have sharpened razor sharp and this works good because the blade has more guts to it than an Exacto knife. My pocket knife has a long pointed blade and a shorter rounded blade. I find the knife will do the same thing as sand paper or a file if it is used as a scraper to scrape the old distorted glued area down to near perfect. And I carve off chunks and even shape windows out, much like whittling.

    But I have another weapon in my kit. It is a set of micro chisels. I keep these razor sharp too. They are real good for getting in areas I can't access any other way. My small gouge is about 1/16" wide and is good for cutting out bolt washers that I cast. My big gouge is about 3/16" accross and is good for cutting holes to start windows. I also have a skewed end chisel that is about 1/4" and it is a honey to carve in fine details. I use the square flat chisels to cut glue out of edges on bits I stuck together and clean off the glue to the smooth surface. And the V gouge is excellent for adding details like wood grains and chips out of the end of boards. I also use the V gouge to clean up some glue joints.

    The blades leave the plastic smoother than sanding or filing and the plastic carves like hard cheeze. I also like how the chips are easier to clean up than the dust created by sanding. More control than a Dremel, although I have one of those too, and it has its special place. I have a few old dentist bits that are really small and they are a honey for some jobs. But I try to use the knife or the chisel set first.

    Of course you need to know how to get that razor sharp edge. A dull knife will cut you sooner than a sharp one (ever hear that? It's true!) Get yourself some fine wet/dry sand paper. Get one sheet of 200 grit, one sheet of 320 grit, one sheet of 400 grit, one sheet of 600 grit and if you can find it, a piece of 1500 grit. I cut the sheets in half as soon as I get them. It makes them easier to store and use.

    You also need some stroping wax, commonly called jewlers rouge. This will give you the absolute razors edge you want. Although you can replace it with the 1500 grit if you can't find any.

    Get yourself a piece of 1"x2" pine about 6" or 8" long. Sand one flat side with 80 grit untill it is as smooth and as flat as you can make it. This wiill stand in for your sharpening stone. It elevates the action of sharpening off the table and gives your fingers holding the knife some place to go. Cut a piece of the 200 grit to cover the wood block. Use the 200 if your blade is in bad shape with nicks missing and needs alot of material removed to form an edge. Christ! this is taking too long!

    Basically it goes like this:

    200 grit to clean up the blade and shape a basic rough edge. Hold the blade up to a light, if you can see a reflection of light off the edge of the blade as you twist the edge towards your eye, you've more work to do.

    320 grit is if the blade was already sharp and you just want to put a new edge on it.

    400 grit is to refine the edge and start to polish the edge. Can also be used to touch up a blade that has just lost it's edge.

    600 grit is to further polish the edge

    Stroping wax is aplied to a piece of card stock like coloring it with a crayon. Get a nice thick layer of wax and then strope the blade, like a barber sharpening his razor. It is not the leather belt that puts an edge on the barbers razor, but the stroping wax he puts on the belt. Draw the blade back and forth over the wax, turning it carfully to drag the blade in each direction. If you have built up a little feathered bit of blade hanging off the edge of your knife during previous operations, then the stoping process is how you remove that. (that little flappy bit of steel is a good sign, so dont worry. It means that you have worked the edge down to it's finest tolerance.) Once you are satisfied with the stroping, wipe off the left over wax with a rag and look how she shines. Don't do the traditional thing, and drag your finger across the blade to see how sharp it is. You will likely cut yourself. It will be so sharp you won't feel the edge, it will feel and appear smooth. Do the right thing and try and cut some wood (always move the blade away from yourself untill your more experianced, of course) That knife is sharp now and will hold an edge (depending on how good the steel is) untill you mistreat it. And then you will be back at your sharpening stand.

    The 1500 grit can be substituted for the stroping wax and produces a fine sharp blade as well. I like to use the wet/dry black sand paper as it is much cheaper than a wet or oil stone, and stores in a small space at my bench and is ready to go when needed. I also sharpen the kitchen knives too. I haven't bought a new Exacto blade in years, I just keep sharpening the old one. ( and it come out sharper than a new one too) I don't recomend using fluid while sharpening. When the paper gets too dull to take any steel off in a pass, you will feel the blade skate over the paper. Time for a new piece.

    I had a hard time sharpening my micro chisels so I glued the sand papers to popsicle sticks and put the chisel in a vise and used the makeshift sanding boards with both hands to file on a new edge.

    Keep your tools sharp.

    Don't cut youtself! :eek: :confused: :cry: :mad: :curse: :oops:

    TrainClown :thumb:

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