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Thread: Keeping things underwater for retrobrite

  1. #1

    Default Keeping things underwater for retrobrite

    I've been retrobriting a few things and the constant problem I have is keeping them underwater. Plastic parts float to the top.

    Sometimes you can use cable ties to attach a spanner or some other weight but often there is nothing to attach to. I tried tape, that failed after a few hours, I tried blutack (well, a knock off version) and that didn't last on larger parts, only the small ones with little buoyancy.

    Any ideas? I was thinking about hot melt glue but the liquid gets pretty warm. My hand isn't calibrated but I'd estimate 60-65C and I'm worried that the glue will start to melt.

    In hindsight I should have made the box with UV LEDs on the bottom, so I can put weights on the top of each part. I only have LEDs on the sides and the top so I can't put things in upside down. But then again I'd be worried that where they touch the bottom they wouldn't get enough peroxide to remove the yellowing and would come out blotchy.

  2. #2

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    I've used string a few times. Just loop it round the item and tie the ends to something heavy. Maybe move it around every few hours if you're worried about the string blocking the UV and leaving a line.

  3. #3
    Join Date
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    Doesn't it's floatation indicate the item is a witch/warlock, and thereby ought to be burned? Don't go soft man.

  4. #4

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    Quote Originally Posted by FishFinger View Post
    I've used string a few times. Just loop it round the item and tie the ends to something heavy. Maybe move it around every few hours if you're worried about the string blocking the UV and leaving a line.
    That's an interesting idea. It takes a long time to work though, I usually leave it for 48 hours so and most of it is while I'm not there, overnight or out. I'd be really worried about it leaving marks.

    For some reason though that has reminded me of something else to try: suction cups.

  5. #5

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    Just flip the items a few times while under water to get all air bubbles out. They won't float after that anymore.

  6. #6

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    Quote Originally Posted by Timo W. View Post
    Just flip the items a few times while under water to get all air bubbles out. They won't float after that anymore.
    Some of them have holes so any air escapes but they still float. The plastic is lower density than the water.

    I'm trying a suction cup. It was from IKEA for 5p so I'm not expecting much. Had a lot of trouble getting it to stick on in the first place.

  7. #7
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    Depends on the shape and size of the item, but sometimes I'll set clear bottles of water on the top of the item. Light can get through, but still move them around a bit periodically.

  8. #8

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    Quote Originally Posted by SomeGuy View Post
    Depends on the shape and size of the item, but sometimes I'll set clear bottles of water on the top of the item. Light can get through, but still move them around a bit periodically.
    Someone else suggested something similar. Ideally find something with small contact points, like legs. Maybe get a plastic fork and use the prongs as legs somehow.

    The more I think about some less crappy suction cups seem like a good option for larger parts. The only down side is that they are kind of thick for small items so you need more peroxide, but small items I could probably use tack or maybe binder clips or something.

    What I really need is a small expanding vice. I don't know what you call them really, basically a normal vice closes to grip the object but I need one that pushes outwards so it braces against the inner walls of whatever I'm retrobriting.

  9. #9

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    Quote Originally Posted by tipc View Post
    Doesn't it's floatation indicate the item is a witch/warlock, and thereby ought to be burned? Don't go soft man.
    No, it just means that retrobriting plastic parts turns them into wood.

  10. #10
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    Perhaps people need to consider whether "traditional" retrobriting is just too aggressive for aging plastics. Maybe the way to do things is to incrementally "bleach" the material (and peroxide is a type of bleach, just not chlorine bleach). Wiping down the surface with full strength or dilute peroxide of whatever strength. Doing it again after whatever length of time. Conditioning the plastic in between slatherings (say with mineral oil? Or some other oil, one that's perhaps petroleum based?). Many things can be kept alive if stored in the correct conditions. And/or treated along the way. Maybe an incremental bleaching won't do any significant damage. The discoloration still may come back.

    I'm sharing this for the upteenth time. I once put a warm coffee mug on top of a Tandy 2000. When I lifted the mug, there was a ring left behind that was much lighter then the surrounding discolored plastic. I don't think anyone really understands this stuff. Someone please consult a chemist and ask why that would happen.

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