I’d like to try my lst latex mold making on a Chooch small cut stone retaining wall. These walls are painted gray but don’t know if they’re solvent paints or acrylic paints. Has anyone used a specific mold release agent with these painted (as opposed to unpainted Woodland Scenics walls)? I’m concerned about my own acrylic (scenicing) paints sticking to my original commercial retaining wall after using it to make a latex casting mold. Will wet water/dish soap be my best bet? Pam cooking spray I imagine will prevent future scenicing painting on the original painted (base coat) commercial product… How far does a jar of Woodland Scenics latex rubber go on average? Can several tunnel portals or retaining walls be made from a single jar? (I think the jars are 16 oz.) Thanks!
I make a lot of my own castings from resin. Walls, girders, signal parts, etc. I still use plaster for rocks etc.
I don’t use latex because making the mold takes too long. You have to use many layers and they each have to dry over night before you can add another or else the completed mold will not cure all the way through. (my opinion) Latex is better for rocks because of their odd shape, but I think RTV is better for walls and girders etc.
I use RTV for making molds because once mixed and poured it will set up over night. (You do have to build a mold box so the RTV is contained.) Then I use casting resin to make multiple parts. Each mold will last roughly for 50 pulls. I use Mann 200 mold release (appears to be a wax in a spray) available from Smooth-On, as well as their Smooth Cast 320 Urethane casing plastic. Their Mold Max 30 is similar to the RTV that I use from Eager Plastics (Available in gallons only). You can get smaller quantities from Smooth-On.
www.smooth-on.com is their web site and there is lots of information available there.
If you are going to make a latex mold, you do not want to put anything on the master. The latex will not stick to it and form properly. If your master is raw plaster or other porus material, yes, paint or seal it so the latex will not soak in to it.
It does take a few days to make a good mold. Also, if you plan to use your mold over and over, after the 2nd or 3rd layer put some cheese cloth over the latex. This gives it added strength for multi use. Another coat or 2 of latex after the cheese cloth.
When you pour plaster into the mold, wet water can be used as a mold release. After you clean up your mold and go to store it, I have seen it recommended that you put talcum powder on it to help protect it.
Good luck,
What you are proposing to do is theft - stealing intellectual property from Chooch.
I will second Cowman’s comments. You don’t need to seal the master before painting on the latex. I have had good results using wet water as a release agent also. On the point about Pam spray I have had very good luck using a generic version of Pam on molds I have made of wood and used to cast plaster bridge abutments and a retaining wall. The spray material did not contaminate the plaster and I was able to stain the castings with a thin wash of Polyscale paint. There is a little learning curve to making molds but after a few false starts I think you will find it to be an easy and fun process.
Joe
I second the use of RTV. Once “dammed” and poured over the master, your subsequent castings will not have any distortion due to a nice flat back of the RTV mold. The RTV will capture the detail far better and produce quite a few more castings than the Latex.
Latex molds require so many coats and curing between layers. Any irregular shape causes propping of the mold to retain the origional shape to reproduce the casting to the origional. The latex can rip and tear much more easily when removing from many of the detailed masters. This won’t happen with the RTV. The RTV mold is quite pliable and even some of the most deep details can be popped from the mold without damage.
ONLY if you are making them to sell. Otherwise you can duplicate ANYTHING you want as long as it is solely for your own use. You can also duplicate items that are no longer being produced and sold as long as production and sales has stopped on the item for at least seven years. You should contact YOUR lawyer to verify this if you are in doubt.
What you are proposing to do is theft - stealing intellectual property from Chooch.
gandydancer says:
ONLY if you are making them to sell. Otherwise you can duplicate ANYTHING you want as long as it is solely for your own use. You can also duplicate items that are no longer being produced and sold as long as production and sales has stopped on the item for at least seven years. You should contact YOUR lawyer to verify this if you are in doubt. The opinions expressed in this post are mine alone, and are just that, Opinions. These opinions are to be weighed against any other information that you may have on this subject prior to using them.
My comment:
This kind of ‘opinion’ is worth every dime you pay for it. gandydancer’s comments are those of what is normally referred to as a ‘guardhouse lawyer’.
In point of fact, I have in my viewing some well-known intellectual property rights which most definitely prohibit ‘reverse engineering’. So no, gandy, duplicating ‘anything you want as long as it is soley for your own use’ is not always legal, and your statements that nobody should put any value other than opinion on your statements is more than warranted.
As it is for mine.
My gosh Captain - you are right next door. Why not drive over to Redmond (Chooch) and ask them ?
Absolutely incorrect. #1 off there is no intellectual property involved, he is making his own mold not stealing or duplication anything Chooch is doing. #2 there is no intellectual property involved as he is doing nothing new and exclusive and for that matter neither is Choose. Resin casting etc. has been around for decades and as far as I have ever been able to tell no one hold a patent on it.I make my own resin casting for car models and have been doing it for almost 20 years and trust me I’m not the first or only guy doing it. #3 he’s making these castings for his own use not for resale. If he were to sell his finished products then there may be some sort of infringement involved.
Chooch would have to be granted intellectual property in the first place by means of a patent, copyright trademark, industrial design rights and trade secret such as the material they make their castings from.
I know this to be fact as I have dealt with the intellectual property team of the firm where I used to work for many years, because everything I ever built designed or created became part of the companies intellectual property along with my name on some 14 patents held by the company.
All that wanna be legal BS aside all the guy is trying to do is make something for his model railroad and save himself a few bucks and enjoy the fact that he made that part himself.
I can’t say with 100% certainty as I don’t have any experience duplicating plaster castings but I think it may be a good idea to clean the paint off. Depending on how well it has adhered to the casting it may or may not come off or mess up the release. Here are a few links for mold release. I know my wife gets all her stuff for molds etc. from A C Moore with the exception of me I came pre-moldy when we met…
http://www.acmoore.com/nsearch.aspx?SiteSearch=ACMoore.com&keywords=mold+release&SiteSearchButton=go