Rosette

Discussion in 'Sand Casting' started by Chazza, Aug 5, 2020.

  1. Chazza

    Chazza Silver

    My sister is restoring a house built in the 1860's and she has been looking for and finding old bric-a-brac for it. I thought I might be able to cast this rosette in aluminium; two failures, one success so far, the bad news is she wants six!

    We think that it originally screwed to the ceiling to surround the light cable,

    Cheers Charlie
     

    Attached Files:

  2. Jason

    Jason Gold

    What size diameter is that thing? It looks pretty easy to me. Silicone mold, wax copy, ceramic shell. Pour it in bronze.... What was the original made out of? Lot's of this stuff was plaster.
    NOW would be the time to duplicate it in plaster of paris reinforced with some metal if desired run in a mold.

    If you are trying to sand cast that, GOOD LUCK! Give up now.
     
  3. Chazza

    Chazza Silver

    Original is brass.

    Why should I give up, if it works casting it in aluminium in a sand mould?
     
  4. Jason

    Jason Gold

    From the looks of the original on the right, I see lots of negative draft... I'm not a sand guy, but I imagine that thing won't pull too cleanly from a mold.
    Is that aluminum version one of your successes?? You didnt say what the diameter of that thing is?? It makes a difference if it's 18inches across or 6inches.

    The original is a really nice piece. Why dink around with aluminum? Sil-bronze is your friend.
     
  5. HT1

    HT1 Gold Banner Member

    can we see the back side of the original???
    that will tell us more about how the piece was made

    there are several ways a piece like this could have been made in the 1800's :
    Repousse
    slush cast, probably in zinc, then plated or painted
    sand cast
    Stamped (Unlikely)
    cast from plaster (from a hand carved wood mold or master ) and gilded,


    the only one of these techniques that would have created backdraft on the original is Repousse, so it is unlikely the original has backdraft, so it should be easy enough to sand cast.

    little note: here im assuming the original is from the mid 1800's which all but throws out the idea of a rubber mold , which is where negative and Zero draft comes from... well now days CNC and Diecasting also have made zero draft prevelant, but that is a thread unto it's own

    as to your choice in metal you can use ANY metal your only real issue is the color you want , the original pictured has a very interesting patina, if it is natural?
    it will be very hard to replicate, even by allowing natural aging
    the base metal is yellow, but it is browning with no green, I suspect it is a yellow brass, probably with some tin ,
    if I was going to try to replicate that look in sand casting I would try a 70-30 brass ( That is the brass shell casings are made from) if you have seen old shell casings, they get that same brown patina , but polish up yellow, and only green if exposed to moisture (or salt) oh and of course 70/30 used to be a very common alloy becasue it was real easy to calculate and cast.

    as to the patina if the original is 1800, that piece was probably hand rubbed regularly(Monthly ), leaving a shine on the highes and letting the lows brown, it can be faked with Birch Casey Metal Antique, and sealed so it will last forever, or if you are somewhere dry away from the ocean, polish them out degrease the finished pieces and hand buff the highs with johnson pastewax, this will protect the highs, for years, but allow the lowes to naturally patina in 20 years you will have the natural patina


    V/r HT1
     
  6. Petee716

    Petee716 Gold Banner Member

    Both this and your other post about dropouts makes me think of the condition of your sand. Not saying there's anything wrong with your sand but both situations can be worsened by sand. I'm assuming your concern is with surface finish. What do your failures look like? I've had both dropouts and surface finish issues and conditioning my sand (petrobond) has improved both. Are you riddling or sifting on your facing sand? Also your pattern being super clean and then graphite dusted into the crannies.
    Pouring too hot can cause surface issues too. Too cold might cause problems with filling a thin casting. Manufacturers are going to make it as thin as they can get away with but you have the luxury of making it as thick as you want to.

    Pete
     
    HT1 likes this.
  7. Jason

    Jason Gold

    Frankly, I'm surprised it's made of metal! It would have been plaster here in the states at that time period unless it came out of a Newport mansion. It's a beautiful piece! No doubt it was originally cast in sand. For the idiot home gamer like me, lost wax all the way. No worries then about details not showing up. Wish you were closer, I'd make them for you in a heartbeat just to have a copy of the pattern! I can think of several places in my house that would look awesome! People in my hood pay big money for unique architectural details like this.
     
  8. Chazza

    Chazza Silver

    • Can get a photo of the back later on perhaps.
    • The failures were probably because the melt wasn't hot enough; or because of gas entrapment.
    • All of my sand is used for facing and filling the moulding box; it is very fine.
    • Diameter of the pattern is about 2".
    • I doubt it was made in the 1800's, as electricity probably didn't get to the house until the 1920's. It may not have been made for lighting at all; I first assumed that it was a surround for a door handle, but the hole in the middle seems too small.
    • I only have the equipment to melt aluminium.
    • I did not make myself clear earlier; I don't have any concerns about the quality of the aluminium one, as it will be used on ceilings about 10' high or higher. If critics can see detail from that far below, then I take my hat off to them. My sister is happy with it,
    Cheers Charlie
     
  9. Jason

    Jason Gold

    2" ??? I was expecting that thing to be around 12" in diameter. A beer can or cigarette lighter next to a part helps when determining scale in a photo.
     
  10. HT1

    HT1 Gold Banner Member

    2 inches.. sounds like a fancy backer for a drawer pull

    V/r HT1
     
  11. Petee716

    Petee716 Gold Banner Member

    You didn't mention if the piece came from the house or was obtained elsewhere. 1860's they were putting gas lights in houses so it still could have have been from that period. It's anybody's guess what it was used for.
    A usable casting is a usable casting.

    Pete
     
  12. rocco

    rocco Silver

    It's a bit of a mystery item, if it were backer for a drawer pull I would expect the hole in the center to be much smaller, just the diameter of a screw and if it were for a ceiling hung light fixture, one would expect it to be large enough to cover a standard octagonal electrical box, at least 4" in diameter. It could still be for a ceiling fixture but then it would have to be just one part of a multi piece cover or maybe part of the finial assembly that holds a lamp shade in place.

    Not that it matters to this discussion, but what does your sister intend to use them for?
     
  13. Jason

    Jason Gold

    At that tiny size, I could see it as a surround where a gas pipe would exit a ceiling for a gas light.

    It's so small, It would cost very little to use solid investment for it and get perfect details. Hell, send it to me, I'll make your sister a dozen of them. Just pay the postage.
     
  14. Chazza

    Chazza Silver

    I don't know, I just received the command to make 6 of them.
     
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  15. Chazza

    Chazza Silver

    Old – circa 1900 – houses I have lived in Western Australia, have had turned wooden pedestals attached to the ceiling in which the electrical connection to the light drop had been made. From memory the connection was covered by a bakelite finisher.

    I suspect that this brass one did the same job, mainly because it is the right size and the hole is the right size as well, however, there is no hole for a screw or other fastener to locate in, so my hypothesis may be wrong.

    Here is a photo of the back showing three circular marks, which makes me think that it may have been die-cast,

    Cheers Charlie
     

    Attached Files:

  16. HT1

    HT1 Gold Banner Member

    I agree with all that, though that rust around the hole could indicate some sort of lamp part they are oft put together on a threaded pipe with super thin nuts on the pipe holding different parts in place in this case perhaps two together formed a ball. we got a lamp expert in here that might have more info hope he chimes in

    intriguing piece none the less.

    Best of luck

    V/r HT1
     
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  17. Petee716

    Petee716 Gold Banner Member

    I was thinking maybe it was a cover for an old fashioned doorbell turn. That would explain the wear on the high surfaces but all the examples I found have screw holes. I'm going with Rocco's theory of the ceiling fixture component and then leave it alone. Happy casting!

    Pete
     
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  18. Jason

    Jason Gold

    That's the million dollar question. How was it secured to the ceiling of the lamp post? Either way, you'll have to come up with some method to get it to hang on to the down rod. A couple of small cross drilled and threaded holes in the nose for some small allan grub screws would be enough to secure it to it's down rod.
     
  19. Petee716

    Petee716 Gold Banner Member

    image.jpeg This example of a chandelier canopy is larger than the op's piece but shows the idea.
     
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  20. HT1

    HT1 Gold Banner Member

    very similiar to what I was thinking , because of the large hole I was thinking of an ornament on a floor lamp pole or big chandelier :)


    V/r Ht1
     

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