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Thread: Acrylic crystal refinishing

  1. #1
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    Acrylic crystal refinishing

    Here's a quick example of how it's done and what can be achieved.......but it takes a bit more than polywtch.

    I received this Speedmaster last week for service and a bit of TLC. The crystal had suffered a deep gouge and looked pretty rough, but before condemning it I thought I`d try to refinish it. These crystals are thick, so refinishing was worth a try. Sometimes there are micro-cracks that only become evident after cleaning up, there's a risk of spending time and effort only to realise the crystal's scrap at the end of it, but given the price of a replacement this was worth a go.

    I don`t intend taking the crystal out of this watch, so the first job was to mask the bezel. I use electrical tape, yellow's the best choice because it's easier to see the edges. Simply run a scalpel blade around the reel to cut it down to a useful width, which also makes it easier to bend and flex.

    Here's what it looked like prior to starting work, the damage is clear to see and the rest of the crystal's not good.

    picture uploader

    First step is to work on the whole crystal using 1500 grit wet and dry wrapped around a small flat rubber block, wetting with dilute detergent/ water and wiping frequently with tissue. The water will turn milky as the plastic comes off, the detergent will ensure the fine particles stay dispersed and don't clog the paper. I work in swirls initially, them assess how the job's going. Not surprisingly the deep scratch was still evident but much shallower. I then worked down the length of the scratch until it was almost gone, then reverted back to an even swirl over the whole crystal, still using 1500 grit.

    Here's how it looked, obviously it gets worse before it gets better and at this point you have an even opaque finish, hopefully without any of the original scratches.



    Next step is to repeat the process using 5000 grit, followed by 7000 grit. At this stage the finish can be assessed, a magnifier will reveal whether all the damage has gone. If traces remain the process needs repeating using 5000 grit to cut a bit deeper. If the finish after 7000grit looks OK the next step is to polish using metal polish on a soft cloth. Solvel Autosol is as good as anything, use a swirling technique with moderate pressure until the crystal looks nice and smooth. Again, assess the finish under a magnifier and if you're not happy go back a couple of stages. In this case I was happy with the results, the initial 1500 grit treatment had removed all the damage and the subsequent steps took the fine scratches caused by using 1500 grit.

    Finally, polish with polywatch for a couple of minutes and the job's done. Thankfully no micro-cracks were revealed.

    [url=https://postimg.cc/Bty31pKD][/url


    The whole process took around 25 minutes. Using the rubber block is v. important to achieve a flat 'levelling' effect which gets the damage out by taking the minimum plastic off. Same principle applies to all refinishing work.
    Last edited by walkerwek1958; 16th February 2020 at 13:23.

  2. #2
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    Excellent result. Something I imagine you have to be quite bold with to start with.

  3. #3
    Master johnbaz's Avatar
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    WOW!

    You did a fine job of that, It looks 1000% better!!

    I've done a few mineral crystals using emery cloth and solvol autosol/T Cut then Brasso as it's finer than the Autosol!

    This Seiko SQ 4004 is a non runner but I had a go as I was bored!!



    I started off by rubbing on a flat surface on the Emery cloth (Used to have a 10mm sheet of glass for this years ago but dunno what happened to it!), I held the watch like this as it was the easiest way to keep it perfectly flat.



    After a good amount of rubbing to get rid of the deep scoring and ready to start on the cutting paste..




    I didn't really finish the job as my arthritic hands were aching by this stage but another ten or fifteen mins on the Brasso would have probably given a better finish!




    Apparently, For mineral glass Cereum oxide does the best job but it comes as a powder that is particularly noxious to the human body if breathed in!


    John

  4. #4
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    Thatís a very useful and informative post, thanks Paul.

    Iíve got a couple of watches with acrylic crystals including a vintage Speedmaster and have so far avoided scratching them. Bookmarked this post just in case I ever do.

    Cheers
    Neil

  5. #5
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    Quote Originally Posted by trident-7 View Post
    Excellent result. Something I imagine you have to be quite bold with to start with.
    As ever, practice on something worthless to start with. It's surprisingly easy. The materials cost very little and once you've got them you can refinish your acrylic crystal easily if it gets damaged.

    I`ve never tried refinishing a mineral crystal by similar techniques and I certainly wouldn't try it on sapphire.
    Last edited by walkerwek1958; 16th February 2020 at 13:40.

  6. #6
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    Quote Originally Posted by johnbaz View Post
    WOW!

    You did a fine job of that, It looks 1000% better!!

    I've done a few mineral crystals using emery cloth and solvol autosol/T Cut then Brasso as it's finer than the Autosol!

    This Seiko SQ 4004 is a non runner but I had a go as I was bored!!



    I started off by rubbing on a flat surface on the Emery cloth (Used to have a 10mm sheet of glass for this years ago but dunno what happened to it!), I held the watch like this as it was the easiest way to keep it perfectly flat.



    After a good amount of rubbing to get rid of the deep scoring and ready to start on the cutting paste..




    I didn't really finish the job as my arthritic hands were aching by this stage but another ten or fifteen mins on the Brasso would have probably given a better finish!




    Apparently, For mineral glass Cereum oxide does the best job but it comes as a powder that is particularly noxious to the human body if breathed in!


    John
    I`ve used diamond paste and a dremel for working on localised scratches on mineral and sapphire glasses but it's very slow.

    Much as I admire your efforts on the Seiko, a new crystal is a better alternative on these. I fitted one last week to the very same watch, cost from Cousins was under £1 using a generic crystal that's 0.1mm thinner. I could've fitted a sapphire for around £13.

    There will be times when a replacement isn`t available or the cost is prohibitive, but replacement is usually my preferred option with mineral/sapphire.

  7. #7
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    If you want to be really fussy you could use 10000 grit wet and dry with some menzerna universal polishing cream dabbed on it.

    That would finish it better than 7000 grit to Autosol combo.

    Autosol is actually quite aggressive, it is used a lot with shagged exhaust pipes.

    The Menzerna one I mentioned is considerably finer than autosol and when you use it with incredibly fine wet and dry it gives a very high end polish if you are patient and take time to step up the grits appropriately.
    It does take time for the very mind finishing to work properly because it barely does anything to the naked eye but at the microscopic level it is working

  8. #8
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    Quote Originally Posted by walkerwek1958 View Post
    As ever, practice on something worthless to start with. It's surprisingly easy. The materials cost very little and once you've got them you can refinish your acrylic crystal easily if it gets damaged.

    I`ve never tried refinishing a mineral crystal by similar techniques and I certainly wouldn't try it on sapphire.
    If your car has yellowing or clouded headlights practice on those first, you'd be amazed what you can achieve.

    I don't go quite as fine on headlights, I think I start with something like 800 grit then go to 2000 and 3000 and finish with something like Greygate plastic polish which is available from camping / caravan shops.

  9. #9
    Craftsman Templogin's Avatar
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    Very impressed. Thanks for sharing.

  10. #10
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    Looks super Paul.
    Cant wait to get the watch back!

    Sent from my SM-N976B using Tapatalk

  11. #11
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    Great job and post, thanks for taking the time - v useful.

  12. #12
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    Thanks for the comprehensive write up Paul. This method really does work; itís worth following all the steps.

  13. #13
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    Nice job Paul, although I would never let one of my crystals get to such a bad condition.

  14. #14
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    Quote Originally Posted by xellos99 View Post
    If you want to be really fussy you could use 10000 grit wet and dry with some menzerna universal polishing cream dabbed on it.

    That would finish it better than 7000 grit to Autosol combo.

    Autosol is actually quite aggressive, it is used a lot with shagged exhaust pipes.

    The Menzerna one I mentioned is considerably finer than autosol and when you use it with incredibly fine wet and dry it gives a very high end polish if you are patient and take time to step up the grits appropriately.
    It does take time for the very mind finishing to work properly because it barely does anything to the naked eye but at the microscopic level it is working
    Have you tried this on an acrylic crystal? Sounds a bit like overkill to me, but it might have some value for steel case refinishing. Getting the final mirror finish on polished stainless is quite demanding, it's all too easy to put as many hairlines in as you're removing.

    The regime I use on crystals gives perfect results, polywatch as a final finish is excellent stuff.
    Last edited by walkerwek1958; 16th February 2020 at 20:18.

  15. #15
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    Quote Originally Posted by alphajet View Post
    Nice job Paul, although I would never let one of my crystals get to such a bad condition.
    The owner of the watch has just bought it off ebay for a good price.....I don`t think anyone deliberately gets them into that condition!

  16. #16
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    A great writeup and just shows what can be done (in the right hands that is) alot of watches are probably written off as people don't know this kind of work can be done.
    Thanks for sharing.

  17. #17
    Master TKH's Avatar
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    after 20+ years of refinishing some very enjoyed watches can only agree that with right tools and practice good results can be achieved as Paul says / demonstrates

    the trick for me is starting with lighter papers at first 2000 to see if it gets the result you require then getting slightly tougher 1500 / 1200 if not, acrylic is really forgiving and quite nice to work on..

    many skating rinks restored...






    and Johnbaz thats great work on a crystal
    Last edited by TKH; 16th February 2020 at 21:00.

  18. #18
    Fantastic result, thanks for posting. If the owner of the watch doesnít mind it would be great to see the work involved in getting the movement working too. Iím sure a few of us would like to see a good outcome on this watch after reading about it when it was bought.


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  19. #19
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    Quote Originally Posted by sandman View Post
    Fantastic result, thanks for posting. If the owner of the watch doesnít mind it would be great to see the work involved in getting the movement working too. Iím sure a few of us would like to see a good outcome on this watch after reading about it when it was bought.


    Sent from my iPhone using Tapatalk
    I'm more than happy for paul to document and post the work involved with my watch.

    It is of course completely up to paul him self whether he would like to!

    Sent from my SM-N976B using Tapatalk

  20. #20
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    Quote Originally Posted by walkerwek1958 View Post
    Have you tried this on an acrylic crystal? Sounds a bit like overkill to me, but it might have some value for steel case refinishing. Getting the final mirror finish on polished stainless is quite demanding, it's all too easy to put as many hairlines in as you're removing.

    The regime I use on crystals gives perfect results, polywatch as a final finish is excellent stuff.
    I do use that on metal polishing to be honest,

    for acrylic I used wet and dry paper and then a leather strop with polishing compound to finish it by rubbing the acrylic up and down the leather.

    I did get the acrylic more polished than new lol, there was very obvious shine and reflection to it that was not there when new.

  21. #21
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    Thanks for posting this interesting write up and photos. Iíve polished the odd exhaust but never a watch crystal, so good to see whatís possible. I just need to find a suitably shagged donor to experiment with!

    Iíd love also like to add my own interest in seeing what happens to this watch through the rest of its restoration. Having read the original thread after purchase with great interest, it would be good to see the outcome.




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  22. #22
    Absolutely lovely job. I need to do something like this on an old datejust so this is very timely!

  23. #23
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    Amazing job, I would of thought that was too far gone. Glad you tried it recover it and glad you took these pictures.

  24. #24
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    What I`ve tried to show here is just how easy it is to refinish an acrylic crystal. The difference it makes to a watch is huge, especially if the watch has a clean dial.

  25. #25
    Grand Master Neil.C's Avatar
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    Quote Originally Posted by walkerwek1958 View Post
    What I`ve tried to show here is just how easy it is to refinish an acrylic crystal. The difference it makes to a watch is huge, especially if the watch has a clean dial.
    Nice job Paul.

    I've polished up a few acrylics over the years but on deeply scratched jobs I always wonder how thin the crystal is afterwards?
    Cheers,
    Neil.

    My Speedmaster website:

    http://www.freewebs.com/neil271052

  26. #26
    Grand Master Neil.C's Avatar
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    Quote Originally Posted by johnbaz View Post
    WOW!

    You did a fine job of that, It looks 1000% better!!

    I've done a few mineral crystals using emery cloth and solvol autosol/T Cut then Brasso as it's finer than the Autosol!

    This Seiko SQ 4004 is a non runner but I had a go as I was bored!!



    I started off by rubbing on a flat surface on the Emery cloth (Used to have a 10mm sheet of glass for this years ago but dunno what happened to it!), I held the watch like this as it was the easiest way to keep it perfectly flat.



    After a good amount of rubbing to get rid of the deep scoring and ready to start on the cutting paste..




    I didn't really finish the job as my arthritic hands were aching by this stage but another ten or fifteen mins on the Brasso would have probably given a better finish!




    Apparently, For mineral glass Cereum oxide does the best job but it comes as a powder that is particularly noxious to the human body if breathed in!


    John


    Very nice job John.

    I've had a go at that in the past and the advantage with polishing mineral crystals is that they are usually flat!
    Cheers,
    Neil.

    My Speedmaster website:

    http://www.freewebs.com/neil271052

  27. #27
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    I have never had the nerve to attempt to polish an acrylic crystal. Thank you for posting the guide, what a great end result.

    Dave

  28. #28
    Master woodacre1983's Avatar
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    Thank you for sharing this Paul. Great work and love reading and learning the techniques. Would you have to refinish the acrylic allot to make it too thin?


    Sent from my iPhone using Tapatalk

  29. #29
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    Acrylic crystals are generally between 0.6mm and 1mm thick. That doesnít sound like a lot, but a deep scratch is usually less than .05mm. As with metal scratches, some material protrudes above the surface ( think of a ploughed field) so the scratch feels deeper than it a actually is. Using a levelling technique ensures that the absolute minimum of material is removed consistent with getting rid of the damage.

  30. #30
    Grand Master Neil.C's Avatar
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    Quote Originally Posted by walkerwek1958 View Post
    Acrylic crystals are generally between 0.6mm and 1mm thick. That doesnít sound like a lot, but a deep scratch is usually less than .05mm. As with metal scratches, some material protrudes above the surface ( think of a ploughed field) so the scratch feels deeper than it a actually is. Using a levelling technique ensures that the absolute minimum of material is removed consistent with getting rid of the damage.
    Cheers,
    Neil.

    My Speedmaster website:

    http://www.freewebs.com/neil271052

  31. #31
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    Quote Originally Posted by Neil.C View Post
    Very nice job John.

    I've had a go at that in the past and the advantage with polishing mineral crystals is that they are usually flat!
    Cheers Neil

    I'd never try a domed one unless it was on my buffing machine, I'd probably break it with the heat produced!!


    John

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