Customs: Sanding plastic on Transformers figures without scratches

Discussion in 'Creative General Discussion' started by WereDragon EX, Feb 16, 2020.

  1. WereDragon EX

    WereDragon EX Well-Known Member

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    My friends and I have experienced some instances where pegs on some figures are too wide for the ports they are supposed to plug into. This has at times, resulted in stress marks appearing on the port as a result of a peg maybe being too thick being fitted into it. Of course, this likely necessitates sanding down the peg in question so that it does not stress the plastic of the port.

    However, in doing this, I am somewhat concerned about scratching up the plastic on the peg were I to sand it. That would adversely affect the aesthetics of the figure, depending on where the peg to be sanded is located on said figure. Not having not much experience with sanding plastic, I would like to inquire as to what grit of sandpaper is best to use for a task like this, sanding down pegs so that they aren't so thick while not scratching them up.

    Or, if there would be scratches in the initial sanding, how best to remove them (either through more sanding or some other polish or buffing agent) so the figure's aesthetics aren't affected. Also, what technique of sanding (dry or wet sanding) should be used in this task? It seems that the technique used when sanding plastic also could affect how the final job looks aesthetically.
     
  2. AutobotSDG

    AutobotSDG Well-Known Member

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    The best way I have found is for using several different grit sandpaper or sticks. I use the nail files with the different levels in one (see attached pic). You can find some that are numbered, which makes it easy to know the highest to lowest, just a matter of finding the right ones. By the time you get to the lowest grit, or the buffing layer, the plastic should be smooth again.

    s-l300.jpg
     
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  3. WereDragon EX

    WereDragon EX Well-Known Member

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    I suppose that could be useful. What sort of grit sandpaper is generally used for those sorts of products? My main concern is scratching the plastic by sanding it and then not being able to fix that. It seems that some people on the internet advise using a rougher grit first to remove the material that you want to remove and then going down to finer grits to clean up the sanded surface (removing scratches and making the surface of the sanded area smooth again). I suppose since plastic seems easy to scratch that I'm a tad wary about attempting something like this without a clear idea or guide on what to do.
     
  4. Snaku

    Snaku Primes Don't Party

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    You're correct that sanding will scratch the plastic. That's exactly what you're trying to do - scratch off enough material to thin it down. Personally I prefer to start around 300 to 400 grit - it takes a bit more work to wear it down but you're less likely to overshoot your goal and remove too much then if you started with something like 80 or 120. Then you just work your way up to higher grits. I think 2500 is the highest I've used before moving on to buffing/polishing.

    To reduce scratching, sand in circles rather than back and forth, especially when you're doing the lower grit sanding - that should prevent creating any deep gouges that are a pain to remove. As for wet/dry, your first step where you're trying to remove material will usually be dry then you switch to wet as you move to finer grits. I'd suggest you just follow @AutobotSDG's advice with the nail file - I've never used one but several members here swear by them, and they're just so convenient having all the grits you need along with the buffing surface. They're meant for creating a smooth shiny surface on fingernails which are softer and more scratchable than plastic so they should have no trouble leaving a scratch free finish on plastic.
     
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  5. AutobotSDG

    AutobotSDG Well-Known Member

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    I honestly couldn't tell you what the grits are on those files but as @Snaku mentioned, they are made for polishing fingernails which are softer, so the grits are definitely not too heavy. Just enough to remove what needs to be removed and smoothed out with the different sides.

    It's understandable to be wary at first, you don't want to mess anything up that you can't fix. Maybe try it on some junker toys you may find at a thrift store or something... doesn't even have to be a Transformers item, just something with similar plastic quality that you can see the various stages of sanding and polishing. If you mess up on a junker or random plastic toy, so what... at least you'll know what works and what doesn't when it comes time to using either the nail files or regular sandpaper/wet sanding.
     
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  6. WereDragon EX

    WereDragon EX Well-Known Member

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    The coarsest grit I tend to use in general is 220 grit. I suppose I'm wary about taking off too much material all at once and want a bit more control over the whole process. Admittedly, this does mean more elbow grease, but better that then taking off too much material and not being able to fix it adequately. I guess the main concern I'm having is scratching the plastic and not being able to get rid of the scratches. Or sanding something too unevenly and it doesn't look like what it did before (such as sanding a peg but it turns out not so cylindrical shaped as before).

    Thanks for the tip on sanding in circles, but I'm wondering how that is going to work on a smaller area, like say a peg that I want to sand down because maybe it's too wide/thick for the corresponding peghole. Does "sanding technique" not matter in that case because the peg is a small and narrow thing to sand and deep/disfiguring scratches are thus less likely to occur?

    What sort of substance do you use to polish or buff the sanded surface after doing all the sanding? I've heard that some people use automotive polish if they don't have a dedicated plastic polish. I've also heard that some use toothpaste or a paste made from baking soda and water as they are mildly abrasive and can apparently buff out minor scratches in plastic and impart some shine to the surface.

    It seems that these multi grit sandpaper nail files are actually a relatively economical option as opposed to actual sandpaper. Seems like you can get them from Wal-Mart or a drugstore/pharmacy pretty cheaply. It also looks like the finest grit on some of these files rivals 2000-3000 grit sandpaper even. I suppose one thing I'm wondering about is how to get good control over what you are doing when sanding with a nail file. If you want to say, sand a peg, you can rip off a small piece of sandpaper and contour it to the curvature of the surface you want to sand (like the cylindrical shape of a peg) and then sand accordingly. It seems much harder to do this with say, a nail file, which is basically sandpaper stuck to a popsicle stick shape. Can you cut or rip off a bit of the sandpaper that is stuck to the nail file to do the same thing with conventional sandpaper?

    I suppose my main concerns about sanding would be being able to sand something more or less evenly, like the aforementioned pegs, and doing so such that I don't warp the peg's shape by say, sanding off too much on one side and not enough on the other. It seems like I'm being over paranoid somewhat, lol. If I do scratch the plastic with coarser sandpaper, it would bother me a little, but apparently, you can use finer sandpaper to fix that or some abrasive like plastic polish or toothpaste. I suppose what I am trying to say is I am wary about screwing up and doing something I cannot fix easily. But yes, practicing on some junker toys/plastic seems like a prudent option.
     
  7. Snaku

    Snaku Primes Don't Party

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    I think at this point you've got just about all the information we can give you and it's probably time to start practicing on junk pieces. If the straight file won't work because of round pegs, then you're probably better off buying all the different grits of sandpaper to work through (though I'd bet the buffing stage could still be handled fine by the nail file - you shouldn't have to worry about it removing too much material on one side during buffing).

    As for polishing plastic, this is what I use. The number 1 compound is akin to a very rough toothpaste while the number 2 is smoother than toothpaste. The number 3 gives it a super slick glossy shine but if you don't want it quite that slick, you can still buff it instead.
     
    Last edited: Feb 21, 2020
  8. WereDragon EX

    WereDragon EX Well-Known Member

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    Yeah, I've done some work on sanding, and fortunately, the pegs themselves are in a common enough color that make it more aesthetically pleasing again is simply a matter of applying some paint in a matching color, which hides the scratches quite well. I generally found that 220 grit sandpaper is best for my needs, though those nail files sometimes helps. Admittedly, there were some screw ups, but fixing that was a matter of applying a thin layer of super glue to the peg to thicken it a bit again.