I have a multiple job that may best be made in a mold and I'm looking for ideas. It's not a terribly detailed item. What materials would you use for the mold and for the cast item? Durability is not a factor in this project and weight or structural strength are not necessarily important either. The finished item will be painted with an acrylic latex most likely.
Thanks and Happy Signing......Marty
------------------ Marty Happy Signmaker Since 1974 Happy Ad Sign & Design Regina SK, Canada S4N 5K4
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Marty...........5 alive need INput! What are you doing? What's the material? Need INput!
------------------ St.Marie Graphics & Makin' Tracks Sound Studio Kalispell, Montana stmariegraphics@centurytel.net http://www.stmariegraphics.com 800 735-8026 We're chiseling every day of the week! :^)
That's why I'm asking! have no idea where to start with regards to materials for both the mold and for the cast item. The cast articles are going to be stylized paintbrushes that will be attached or glued to a wall. Enuff info fer ya..... Marty
------------------ Marty Happy Signmaker Since 1974 Happy Ad Sign & Design Regina SK, Canada S4N 5K4
How BIG are the finished parts to be? That's the big question.
What kinda weight restrictions? Obviously if it's glued to a wall it cant be too heavy, but that depends on the wall. =) We could cast the sucker outta solid lead if it's goin on a concrete wall, or urethane if it's gotta be lightweight.
I build molds and prototypes all the time, I've done everything from tiny logos with CNC Laser cut lettering for custom jewelry, to injection molds for plastic parts, to fiberglass and CNC cut steel molds for boat hulls and autobody presses.
Size and weight requirements are the big issues here. You want to use a material that's cheap and plentiful enough to fill the volume without being too heavy, and also offers the fastest turn-around time.
Can you lay-up fiberglass?
How about a plaster mold?
If the parts gotta be big, you dont wanna fill the back of the mold with a solid or heavy material cause it makes the mold heavy, not to mention the shear amount of material it could require.
Most of my molds are fiberglass shapes about 1/4" thick, with a wood or aluminum or steel framing bonded to them for support and stability. You could use a fiberglass mold for casting other fiberglass parts as well as casting an item in expanding urethane foam or other plastic.
How big do the parts need to be? That's really the determining factor right now.
------------------ Mike Pipes Digital Illusion Custom Graphics Lake Havasu City, AZ http://www.stickerpimp.com
[This message has been edited by Mike Pipes (edited August 30, 2001).]
Posts: 8746 | From: Lake Havasu, AZ USA | Registered: Jun 2000
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The objects I'm planning on molding are about 20" long and 4" wide and maybe 2" in depth. The plaster mold sounds simple. Not sure I want to mess with fibreglass. I would prefer a fairly lightweight end product that could just be painted and glued to the wall. This is a whole new ballgame for me and I'm just looking for ideas from someone who's been there, done that!
Thanks and Happy Signing.....Marty
------------------ Marty Happy Signmaker Since 1974 Happy Ad Sign & Design Regina SK, Canada S4N 5K4
sculpt in plaster of paris, make a mold of fiberglass, and lay fiberglas in that mold. Its cheap ($50-100 for all would be reasonable including test and screw-up material), fast, and makes solid, long lasting parts that can be easily decorated.
Plaster and 'glas are a lot less messy and a lot cheaper than HDU, IMHO.
------------------ Robb Lowe Hub City Graphics Spartanburg, SC
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marty ive done "sand casting"...think this is were you want to go...you only need 3d on one side right?get 1x4, 1x6....make box set on table or ground...fill with play sand, moisten it til it will hold together, reverse draw object in the sand(this you do for the 1st one only)once you have it lookin the way you want..then mix up some plaster and pour it into depression, slowly at 1st so you get a good coverage on the bottom..then fill it to the top....let harden and dry then repeat process but now you have a mold to press into the sand.....
------------------ joe pribish-A SIGN MINT 2811 longleaf Dr. pensacola, fl 32526 850-944-5060 BEWARE THE TRUTH.....YOU MAY NOT LIKE WHAT YOU FIND
Posts: 11582 | From: pensacola, fl. usa | Registered: Nov 1998
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Ahhh... OK.. I think plaster is the way you wanna go then.
I'd probably start off with modeling clay for the original, working on a glass or otherwise smooth table. I'd put a coat of mold release wax down on the table (you could even use shortening or veggie oil) so the clay and plaster will release from the surface easier.
Build the clay model on the table with all the detail you want or dont want.
Mix up your plaster. At first I like to make the plaster a little on the thin side so when I apply it to models/prototypes it's sure to pick up the details, then I add a little more powder to the mix to thicken it up, which I then apply in heavy blobs to build thickness quickly yet keep the plaster from running off the model.
Make sure you cover the whole model very well, and make sure the plaster flows from the model onto the table surface so you get a nice flat flange around the edge of the mold.
Let the plaster setup completely, then pull it and the model off the table. This is where the mold release makes things easier. Then the clay should come up out of the plaster mold pretty easily because modeling clay is oil-based anyways and wont stick to much of anything.
Now you can cast plaster reproductions from the plaster mold, but be sure to use plenty of mold release before pouring the plaster in. You might want to reinforce the mold with more plaster, or even set it into a box filled with plaster to eliminate any chances of the mold breaking and to also stabilize it.
Check out the link below.. this is a page on my site dedicated to my truck, which I am underway customizing. I show some detailed pics of building prototypes and casting molds from them.. one project all done with fiberglass prototype and mold, the other started off with plaster molds which has ended up with solid cast resin master prototypes, and will eventually wind up as Silicone rubber molds to cast carbon fiber parts. =)
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I worked in a Museum for a while and the moulds were made of plaster, a dentist's plaster. A handy idea on larger moulds is to break apart rope (we used non synthetic) and after the initial thin layer is on mix the rope with the plaster. Stregthens it up. Rope imbedded into the plaster apart from a couple of loops enables it to be lifted easily Kerry Wright Print Wright AUstralia
------------------ Kerry Wright Gladstone Australia
Posts: 119 | From: Gladstone, Queensland, Australia | Registered: May 1999
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Marty, I have done quite a bit of moldmaking as a sculptor. To simplify a good mold I would:
Create a release by coating the item with greensoap and let dry, or better yet coat with shellac.
Then with a stiff brush, brush on tube silicone ( clear works the best so you can see bubbles and brush them out). Apply in 1/8 inch coats and let dry a day on each coat.
It will take a few days for the mold to become strong and set up enough to use. Then you make a 2 piece plaster mold to back up this silicone, as it will be floppy when you remove the pattern
You can cut the silicone up the side of the pattern with a jagged cut that can find its way home when put back together, Remove the pattern, and pin back together.
You then reback the silicone with the 2 piece plaster and pour your material. Most materials will not stick to the silicone at all and release well.
This will give you a high detail, easy to remove mold.
I use a much higher grade of silicone at 120.00 a gallon for my molds, but the tube silicone will work for simple detail and will last a while. It's biggest drawback is its drying times. The silicone mold needs to end up about 1/2 inch thick.
There is a book you need to add to your collection:
The Prop Builder's MOLDING & CASTING HANDBOOK by THURSTON JAMES Better Way Books Cincinnati Ohio 1989
It will tell you how to make the molds and even use materials such as Durhamn's Rock Hard Wood Putty for casting.
Great for learning about cold pour plastics and latex rubber molds, simple vacuform plastic molds...why you can even make your own Halloween mask!
If you can still buy books through the Letterville/Amazon link then try that.
I got my copy from Barnes & Nobel for $17.99
Hope this helps!
------------------ Draper The Signmaker Bloomington Illinois USA
Get To A Letterhead Meet This Summer! See you there! DUCK SOUP SPLATTER JAM Sept. 14,15,16 Somewhere in Alabama -------------------- 309-828-7110 drapersigns@hotmail.com Draper_Dave on mIRC chat
Posts: 2883 | From: Bloomington Illinois USA | Registered: Nov 1998
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I favor Mike Pipes process. I'd consider coating the modelling clay with spray can shellac before poring plaster on it. For a mold release I've used PAM, that stuff to keep food from sticking. With any mold release that contains any amount of silicone you need to do a soap and water wash to get that stuff off so paint will stick. You'll know by the fish eyes if this step is needed. You can also imbed a bolt with large flat washer into it before it sets up for mounting, so the weight is not just held by glue.
------------------ The SignShop Mendocino, California "Where the Redwoods meet the Surf"
Posts: 6712 | From: Mendocino, CA. USA | Registered: Nov 1998
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If this is a small/one time project, check out your local craft stores. Tap Plastics here in California has little mold resin kits complete with instructions.
Also, someplace in my disorganized library of technical literature, I have a book that describes all of the common molding techniques with instructions for some, pros and cons of each, and with a source of materials. It came from a small company in Tennessee and that is all I remember. Maybe this will jog a memory for another reader. Vic G
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When it comes to mold making, nothing beats leaving a loaf of bread in the breadbox for a month.
Back to reality. I have to make 18 indian heads for the logo portion of golf course tee signs. I'm contemplating making my own or sending out an HDU carved master to a company that specializes in this. Would this be too much of a project for a first time molder? These would have to be outdoor durable of course and will be attached to sandblasted HDU signs. The size will be a 4 to 5 inch circle.
------------------ Dave Sherby "Sandman" SherWood Sign & Graphic Design Crystal Falls, MI 49920 906-875-6201 ICQ: 21604027 sherwood@up.net
Posts: 5396 | From: Crystal Falls, MI USA | Registered: Apr 1999
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Naaaahhh you dont need to send out your master to have a mold cast from it.
Mold making and casting is a snap.
Just be sure your master has the finish you want the final parts to have because every feature on the surface (including fine 1500 grit sandpaper scratches) will transfer into the mold, then back into the finished pieces.
You may not be worried about the surface finish at all, say if you need to hand-paint each one once they're done.
I'd use a rigid mold for that project. Maybe a fiberglass or solid resin mold for dimensional stability and durability since you need 18 finished pieces.
Spray a coat of PVA into the mold, let it dry, then cast the part... use a casting resin for the part too, it's easy to use, cheap, and it cures in minutes. If ya cant get the part to release from the mold, drop it into a bucket of water. The PVA will dissolve and the part will come free.
------------------ Mike Pipes Digital Illusion Custom Graphics Lake Havasu City, AZ http://www.stickerpimp.com
Posts: 8746 | From: Lake Havasu, AZ USA | Registered: Jun 2000
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I like the idea of solid resin for both the mold and the end product. Solid resin is sort of a plastic if I'm not mistaken. Is that correct. Is it a two part system that hardens chemically. And where would something like that be available? I inquired at a couple of art stores and they had no idea. Sometimes it sucks to live in an agriculture-based economy in the middle of the prairies!
Oh, what is PVA?
Happy Signing...... Marty
------------------ Marty Happy Signmaker Since 1974 Happy Ad Sign & Design Regina SK, Canada S4N 5K4
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I have a close friend.....he does work for Disney,Universal,Sea World,etc.He's a master at molding ...he now lives in the sticks and,would be great for anyone needing anything cast.This man is an incredible airbrush artist also....Visual Link...936-264-2617...I don't mean to go on and on,but this man is incredible!
------------------ Stephen Michael Robinson Steve's Pinstriping Houston, Texas
Posts: 71 | From: Spring, Texas USA | Registered: Aug 2001
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Yes it's two parts, 100% solids and there's two types.
There's polyester casting resin, and there's epoxy casting resin. The epoxy resin is the stuff used to coat bar tops and tabletops for a hard, durable and water-clear surface, but the polyester stuff is cheaper and more common in art supply shops.
I know dickblick.com carries it, but you can also check any fiberglass suppliers. Sometimes fiberglass suppliers will have the casting resins in larger amounts.. gallons, 5 gal pails, etc.. but make sure it actually is CASTING Resin and not regular polyester resin for fiberglass layup. Casting resin is designed to be poured thick, regular polyester resin will warp and after time the surface starts to pucker and get wavy.
You can also look up urethane resins.. in fact if you check out urethanes, get the water clear stuff cause then you can use it for doming and 3D effects on your other work.
Almost forgot the PVA question.. =)
PVA (Polyvinyl Alcohol) is a liquid parting agent for casting from molds. You spray (or brush) it into your mold and let it dry. It forms a verrrrrrrrry thin film between your mold and cast part, to make releasing the part easier. It peels up easily and also washes away with water after casting.
Below is a pic of a PVA demonstration I did on my truck. You can see the area of the fender I sprayed with PVA, and that's my finger in there peeling up a small part of the film. It's a very very very thin film and works wonders for releasing parts, especially on a brand new mold where mold release wax just isnt enough until ya pull 4 or 5 parts from it and it becomes "seasoned".
------------------ Mike Pipes Digital Illusion Custom Graphics Lake Havasu City, AZ http://www.stickerpimp.com
[This message has been edited by Mike Pipes (edited September 01, 2001).]
Posts: 8746 | From: Lake Havasu, AZ USA | Registered: Jun 2000
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Thanks for the info Mike. But I'm still a little blurry as to what to make the mold from.
I remember a demo at Mazeppa. The guy made a mold that was very pliable, some what like rubber. He was able to release the part from the mold by peeling or distorting it slightly. Any help on what it is and where to get it would be appreciated.
------------------ Dave Sherby "Sandman" SherWood Sign & Graphic Design Crystal Falls, MI 49920 906-875-6201 ICQ: 21604027 sherwood@up.net
Posts: 5396 | From: Crystal Falls, MI USA | Registered: Apr 1999
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