Thanks Keith for the reply,
2 Hours seems like alot of time to mix,Why not pour 2 parts in mixing bowl and use a drill & small paint paddle to stir together well ???
You have to pardon me but what is milk glue?
I'll look for your post,I'll probably contact manufacture for his directions on this.
Thanks again
Hogwire
Hog, hey .. lol.. I can only find one jug. So, good thing I've already shown a pic .. a couple reply's above.
But in answer to your question. Yes.. its seems you are a painter.. and know what to do. But when I got my jugs.. you could see a bit of 'displacement'. Its kind of 'oily' and needs to be mixed up real well. I chose to watch a movie and just kep turning up side down.. and back again. I knew of no other way~
I think the 'small note' on not scraping the cups.. was / is a problem.. of not mixing correctly. Like I said.. sounds like you've got it all under control.
But hey.. when you get it.. report back and take a few pics. I'd like to see if its mixed pretty well. If you have any questions .. go ahead and ask.
Milk glue.. I"m sorry.. Elmers.. white glue... lol. All and all .. its pretty simple and fast. Just take a bead around the edge of the master so no silicone will leak underneath. Master is face up. I make my own frame.. as shown in the above pic. That allows me to just glue the bottom with paper.. and its easy to peal off. I also add wood to the master to make it a bit thicker to handle. Using white glue.. is good enough.. soak it.. and it comes off again.
Ok, but you asked how to make a latex mold. I replied.. just go to youtube. First hit..
http://www.youtube.com/watch?v=h5ozmmKQeIo
This latex mold took an awful lot of coats. 20 coats plus a 'boot' in which he calls a mother mold.
I ask, how much will all this cost.. plus applying 20 coats of time.. spread out no more than 24 hrs of 'in between' coats. I went to the train show and looked at some rock molds. I bought this one.. I believe it was called Brandon.. or Bragdon.. lol... but he had nice molds. Tons of them. I only had so much money, so I spent some time just looking and bought 3 molds. This one was I bought for $18 dollars. The other two were $15 and $25 dollars. Thats all I could spend, (wife) and so I bought the 3 best molds you could get. The guy I talked to was really nice.. for all I know.. Brandon himself. He explained some of the molds.. and how and why to use each one.
But getting to the point. You can buy some nice rock molds.. to use endlessly many times over in many shapes.
This particular mold.. I reversed.. or should I say.. instead of concave.. its convexed? .. lol.
Got a bananna anyone? I laid down a bananna on the table, taped it down with painters tape.. just the opposite of how you would normally pour a mold. I used a small brush.. and painted in the plaster.. into every little crack.. then applied plaster strips.. smoothed it out.. and.. well you'll have to wait to see the finished product.
But in terms of making a portal mold.. it might be cost effective.. but as far as rock molds.. you can buy nice ones for as little as $15 dollars. But as far as time.. no.. plaster is not 'time effective'. I'd rather use my time making fun molds like this one.
After I painted the plaster into the cracks.. I laid down the plaster cloth.
But hey.. like I said.. after putting 5 coats of latex down.. you might be wishing your money was better spent on silicone.. Just a time verses money factor I guess.
I was thinking of using large Lego bricks for the walling of the master ?
What do you feel about this ?
Interestingly, I just yesterday I scanned an article from an old MR into a computer file about using Lego blocks to form molds. The pictures showed a building front laid out with blocks, and other blocks taking the spots of windows and doors. The person writing the article mad a plaster casting using the mold. Definitely sounds doable and practical. In the next day or two, I'll be scanning another article on making latex molds.
Somewhere in the unscanned mess, I believe I also have some copied articles about using Lego blocks as jigs for holding things together while gluing,
5500 pages scanned, only about 30000 more to go.
Since this original question has been giving silicon rubber its attention, I thought I should point out some other advantages of the material. I worked in a professional model shop in New York for 16 years and we had a casting department that used silicone molds exclusively. I designed molds for the models that we were going to cast, ususally 10 to 50 pcs, and mostly in epoxy. The biggest advantage of silicone vs latex is that the silicone mold can be 1 or 2 inches thick in one pour. Because you can pour that thick you can make 2 or more piece molds allowing you to cast solid parts with detail on all sides, not just the front and side as with latex. We made molds of bottles for Avon decanters with incredible detail reproduction. As a prank one of the casting guys molded his thumb and the casting had fine hairs on it! This is a more complex but really easy process once you see how the molds are made.
One other point: I made a few masters from modeling clay on a sheet of acrylic and made the mold over it and then cast it in epoxy, a real nice effect.
I realize this could get rather complicated and too long for this forum, but if anyone is interested in more detail I would be glad to discuss it further.
Bob
Life is what happens while you are making other plans!
When I was in art school, in a class called "Plaster Workshop," where we learned about making patterns and molds, we used to give a bare plaster pattern a liberal coating of "tincture of green soap" as a release agent. As I recall (it WAS a few years back) we never had any problems removing the pattern from the mold.
There is one very large caveat, however! Beware undercuts!!! Better to make a multi-piece mold than have just one undercut. An undercut will give you fits getting the original out and you'll probably damage the mold in the process!
BiL Marsland (P5se Camelback) Lehigh Susquehanna & Western Northeastern Pennsylvania Coal Hauler All Camelback Steam Roster!! "All animals are equal, but some are more equal than others" -- George Orwell, Animal Farm, Chpt. 10
I've been building another subway station, and in the process I decided to upgrade the homemade latex molds I use for the wall and platform castings. The originals, my first molds, had no side walls so I had to use a styrene frame to keep the plaster in while it set up. This seemed silly, so this time around I made one last casting with the styrene frame, and then added side walls with latex. This was quite easy, and done in a few days with only 3 quick applications of latex. For those making your first molds, remember side walls.
I also added a mesh backing to one of my molds. It really does help keep the mold flat, particularly for the large flat tile molds I use for the subways. I went out to the garage and found some of the mesh that goes down on flower beds to control weeds. It works great.
It takes an iron man to play with a toy iron horse.
i know this is an old post but i just found this web site. anyway, i used some air drying modeling clay and rolled out a piece that was 6"X4"X1/4 thick. i let it start to dry, then took an exacto knife and started carving out small areas that became my stone wall. when it looked good i waited for it to dry then bushed somekind of sealer my wife had for her crafts. then i just used house hold latex silicone and spread it on with a putty knife. i made sure not to make it too thick, 1/8" at most. then when it dried, i could just peal it up. i painted it and it looks great. i would just cut out the shapes i needed. i could reuse the mold over again without any trouble.
hope this helps