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| daves |
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 Registered Member #105 Joined: Wed Jul 15 2009, 12:01pmPosts: 2498 | This is something a little different from your model ship building log. This is my adventure into the creating of molds for casting reproductions of original carvings. It is not quite as easy as it seems and there are a lot of pitfalls and problems to over come. To begin I am working with the stern of the Oliver Cromwell and this is the original art work drawn by Harold Hahn.  Here is the original carvings I will attempt to reproduce. This is a carving done in boxwood by Janos Nemeth you can see more of his work at the thread "a few maritime carvings" right here in this forum under general build logs  | ||
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| daves |
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| Registered Member #105 Joined: Wed Jul 15 2009, 12:01pmPosts: 2498 | To begin there are a few choices of molding material to choose from Latex molding compound, liquid silicone molding and a Composimold heat and pour rubber which you heat up and pour over your pattern and finally a product called blu-Sil CMC. Here is the first pitfall not all molding materials are compatible with the casting material. This I found out the hard way by pouring a castable resin into a Latex mold and it glued itself to the latex mold. | ||
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| daves |
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| Registered Member #105 Joined: Wed Jul 15 2009, 12:01pmPosts: 2498 | here is the first test castings I used the casting resin from Micro Mark. I don't think this will work because it is like the expanding foam stuff. top is the original carving the lighter piece under it is the casting when you look really close it looks like a rough finish with tiny bubbles, so I will try another product called Clear Cast epoxy resin. The thing is Micro mark stuff hardens in about 5 minutes the clear cast takes 3 days.  | ||
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| daves |
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| Registered Member #105 Joined: Wed Jul 15 2009, 12:01pmPosts: 2498 | using clear cast epoxy resin makes a huge difference in the quality of the casting looking close the surface is so smooth  the problem is air getting trapped and as you can see in the lower right the resin stuck to the latex mold and ripped a pieces out. what I want to do is create a faux ivory which can be done with the epoxy resin because it produces a translucent quality the micro mark stuff is a flat color. You can wash down the carvings with a weathering color used by model railroaders and make it look like old ivory. As I mess around with mold making and casting I wonder if that is acceptable in ship modeling in general. What brings up the subject are comments made on another forum such as "at least there is no plastic used on the model" and other comments made that seen to make anything of plastic or resin such a sin. I have tinted the resin to look exactly like ivory or Boxwood to such a degree you could not tell the difference. When you look at a tiny boxwood carving there is no visible wood grain it looks like plastic. | ||
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| dave1254 |
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| Registered Member #2647 Joined: Fri May 25 2012, 08:08pmPosts: 447 | Dave For obvious reasons I like the clear resin better. I was wondering if you put the mold on a table that vibrates. As you pour the vibrations cause the air to rise. I guess you want the hole you pour into at the top so the air escapes. I have been trying to figure out how to do the moldings around the outside of the Sphinx. They are basically leaves on the stems joined into one long piece. I see now I have to make one good copy out of wood then make the molds. The other thought is what about a mold release agent so there is no chance of it sticking. Dave | ||
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| Norman |
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 Registered Member #1932 Joined: Fri Dec 02 2011, 10:02pmPosts: 170 | I have seen someone using a home made vacuum chamber to pull the bubbles out of epoxy castings. That worked well. | ||
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| daves |
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| Registered Member #105 Joined: Wed Jul 15 2009, 12:01pmPosts: 2498 | there is no time to vacuum or vibrate the Micro Mark casting material because it begins to set in less than a minute, by the time you pour the mold it is set. here is what the instructions said about bubbles when using Easy Cast epoxy resin 4. BUBBLES: EasyCast has been formulated to self degas within a few minutes of pouring under most casting conditions. However adding fillers such as granite or metallic powders can result in a cloudy, bubble filled mixture. These bubbles will slowly rise to the surface of your cast. If needed use a hair dryer and pass heated air quickly over the EasyCast surface to remove bubbles. Be careful, excess heat can melt or warp plastic molds.  the mold is open on the back so what I did was to use a stir stick from Mc Donalds and paint the inside of the mold surface. This really helped to get rid of surface bubbles but I missed the area to the left. I cast a bunch of new pieces using a mold release so I will see what happens. | ||
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| daves |
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| Registered Member #105 Joined: Wed Jul 15 2009, 12:01pmPosts: 2498 | dave1254 wrote ... I have been trying to figure out how to do the moldings around the outside of the Sphinx. They are basically leaves on the stems joined into one long piece. I see now I have to make one good copy out of wood then make the molds. Dave actually there are a few tricks you can look into check out this link http://www.marysminiatures.net/index.php?main_page=index&cPath=601 there are lots of miniature things you can use in the doll house hobby to repurpose for ship decorations. Or rather than trying to carve the master piece it is way easier to sculpt it in clay then bake the clay into a hard pieces for making a casting mold. I have also be known to plunder jewelry supply sources looking for stuff like this brass leaf sprays. These are approximately 44mm brass leaf sprays. They have a 2mm center hole. There are also some tiny recesses where you could apply tiny flat back rhinestones that measure about 1mm. so if the hole in the middle is 2mm you can guess the size of the leaf. There are thousands of items you can use to make ships moldings, carvings and all that stuff.  | ||
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| dave1254 |
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| Registered Member #2647 Joined: Fri May 25 2012, 08:08pmPosts: 447 | Thanks Dave I never even thought of the minaiture doll house stuffAs you can see by the detail in the photo I should be able to replicate the leaves and maybe even the lions head. Anyway I will continue to watch this thread with interest and when I get to that point when I build the Sphinx I may have some ideas. Dave  | ||
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| daves |
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| Registered Member #105 Joined: Wed Jul 15 2009, 12:01pmPosts: 2498 | before graphic art school I was a tough guy biker so this is something any respectable biker would never admit, it's true I was a closet piper. what is that? a cake decorator never did it as a job but I took classes in doing it. To me art is art if its on a cake or motorcycle tank, a car or the side of a van or on paper. Anyhow, to do the carvings on the side of the Sphinx I would pipe it. Piping does take some practice but you can get the hang of it much faster than trying to carve.   You can use a polymer clay you bake. Make the clay very soft and pipe it once the design is done then bake it so it turns hard. There is a huge selection of colors so you can make the carvings look like anything.   you can make your own piping tips or buy them. There was an on line class teaching how to pipe figures, scroll work, borders and most anything you can think of. Google images cake piping you will be amazed at the work that can be done this way. | ||
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