enamel watch and clock dial decals

Discussion in 'Horological Misc' started by KANEHUGHES, Apr 1, 2017.

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    KANEHUGHES New Member

    Mar 23, 2017
    I'm creating a clock and I'm currently trying to find out the best way to lay decals over fired black enamel dials. The problem I'm having with the decals that you can print and fire on is that they wont do them in white and I'm worried any other colours normally used wont be bright enough to show on the black. What ways were traditionally used to print onto the enamel dials, other than hand painting? and what would be the best option for me to use?
  2. JTD

    JTD Registered User

    Sep 27, 2005
    Welcome to the board.

    I'm not entirely sure I understand your problem - your heading mentions 'watch and clock decals' but then you say you are creating a clock, so I am a bit confused. That may just be me.

    However, I think you would likely get a better response if your post was in another section. Perhaps 'Clock Repair', even though technically I suppose you are not really repairing anything, I am sure a moderator can move this post for you to the better section.

    Meanwhile, some photos of what you are trying to do would be a great help in giving you information and/or advice.

  3. Ralph

    Ralph Registered User

    Jan 22, 2002
    I've seen black enamel dials with silver or gold numerals, more often then white. Silk screening might be one method for applying the numerals.

  4. ClipClock

    ClipClock Registered User

    Jun 20, 2013
    You could get a stencil made up, it isnt very expensive to have done. Then spray paint the numerals. It'd look very smart
  5. Tom McIntyre

    Tom McIntyre Technical Admin
    Staff Member

    Aug 24, 2000
    I think the key to the issue is that he intends to fire the dial and is looking for hard enamel white on black. Is there a living example of one of these? Black on white is my recollection of all fired enamel clock dials.

    A decal in this context is enamel on rice paper or some other thin paper that is laid on the dial wet and then dried baked and finally fired at a temperature that will burn off the paper and melt the enamel on to the dial.

    Like Ralph said silk screen is a more available technique than decals for a large object.

    I would think it might take a lot of layers and several firings for enough contrast with white on black.
  6. glenhead

    glenhead Registered User

    Nov 15, 2009
    I'd recommend going to a forum on ceramics. They'll have a heckuva lot more of an idea of how decals act and react on enameled surfaces, and would know more about alternatives. Good luck with this - I hope you'll post pictures of the result.

  7. MartinM

    MartinM Registered User

    Jun 24, 2011
    Would reversing the process produce the desired result.
    Do a black 'decal' over white porcelain.
    Essentially, a negative of the more common version, but done in the exact same manner.
  8. Tom McIntyre

    Tom McIntyre Technical Admin
    Staff Member

    Aug 24, 2000
    I have seen watch dials done both ways. I think the black cover with omissions over a white base is the more common.
  9. Bill Ward

    Bill Ward Registered User

    Jan 8, 2003
    #9 Bill Ward, Apr 12, 2017
    Last edited: Apr 12, 2017
    The word "enamel" has several meanings.
    True, or vitreous, enamel is powdered, often colored, glass. White enamel of this sort is really just clear glass with a white powder dispersed in it, making it translucent. It has very little covering ability, especially over a dark substrate. This is why enameling of high quality is often done over polished copper, silver, platinum, iridium or gold- it brightens the light colors. You can see just how transparent true enamel is in an engine-turned enameled piece; the ridges are completely visible right through the layers of enamel. So, true enamel over black probably won't turn out all that well on a dial. You can see this effect on the grisaille medieval enamel panels from Limoges; the translucent effects were produced by multiple layers of white, and by selectively grinding off parts of the white. They're beautiful, but quite dark. You also have to consider the fusion temperatures of these enamels; you don't want to melt the ground when you fire the next layer. Usually, the lighter colors fuse at a higher temperature than the darker, for the above reason.
    Enamel also means a fired smooth paint. This is what we see on those 19thC Swiss scenic watch dials, and also on some 19thC stained glass painting. These paints are usually pigmented, so they cover better. I guess you could screen print with these. They're available from stained glass suppliers.
    And, of course, enamel also means just a glossy paint, of any sort. That's what you'd get at the hardware store. Probably not appropriate, nor permanent, for dialmaking.
    I can't recall anyone mentioning the use of printed, ceramic-type decals for enameling on metal, though that doesn't mean it hasn't, much less can't, be done. The clock supply catalogs sell (or used to sell) rub-on draftsman decals, but these aren't too permanent.
  10. Tom McIntyre

    Tom McIntyre Technical Admin
    Staff Member

    Aug 24, 2000
    The word enamel is used pretty loosely, but I was talking about fired glass enamels. I would not call the white oxides "powder" since that is the core technology of all enamels. The red enamels for example have gold in them. I think that white is typically lead oxide in older enamels and probably titanium dioxide in more modern ones. I see some advertised that are supposedly opaque.

    The firing temperature is really the big issue. O'Hara imported their enamels from France as glass billets and ground them themselves. In order to get a really good white base, they used at least 3 layers of white with decreasing firing temperature for each. As Bill said, the more color the lower the temperature in general but I think that is not a given, just the way the world is.

    So, some clever chemist needs to figure out what oxides that fire white have a really low firing temperature maybe around 700C or possibly a little lower.

    Pure silicon dioxide melts at 1600C. The glass is actually a solution of the colored oxide in silicon dioxide. All solutions have a lower melting point than either of their pure components. (Feel free to substitute "alloy" for "solution" if you like.)
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