I have a mold problem on my layout.

There's also plaster of Paris, usually in 20 - 30 lb bags at Home Depot in the paint aisle.

There are also a variety of plasters called molding plasters which are usually available in small containers.

If you want to get away from plasters there are the Bragdon Industries geodesic resin casting products. This is a more expensive option, but has lots of advantages.

Bragdon website

Jim

Stephen,

Mold is no laughing matter. I am extremely allergic to most molds, and it makes my life no fun.

This is what I have done to absolutely eliminate all mold in my basement:

Buy a de-humidifier and a hydrometer for your train room. This will help two fold. reduce humidity will save your equipment and tracks from oxidation. Run it regularly. Michigan has days of 100 percent humidity and some days it run continuously.

Buy an electronic air cleaner for your furnace, also a good air cleaner to boot. Not only will this keep the colds away, but reduce your allergies away as well.

Finish your basement, seal the walls with a good paint sealant, drywall and paint. this will keep the water and humidity from seeping through your walls, don't forget a good vapor barrier between the concrete and stud walls you install.

Paint the concrete floor. Moister likes to seep up from the floors as well, best to use a good concrete paint for this, then add a floor covering.

Do not let the AC unit drip condensed water on the floor, make sure it is plumbed to a proper drain and covered. the same with your sump pump.

BTW have you taken a humidity reading in your basement?  Is it above 55 percent?

Uhh..J Daddy…I believe you're thinking of a different kind of "mold."  

Lol your right! 

What is funny is I have never heard of Hydrocal creating/causing mold!

yes use the Plaster of Paris....

Molding Plaster. It's the stuff that they used for crown moldings when they were made out of plaster. You wont find it at home depot of lowes. You'll have to look for a builders supply place or an old fashion lumber yard. I bought a 50lb bag here in Cleveland for $14.

J Daddy, you are 100% correct and I apologize. I was just being the class clown again.SteveP.

Stephen,

I just used Plaster of Paris on over 150 rock molds and counting.

It's cheap by the 20 pound bag at about $9.00 and it works great for the rock molds.

I even started tinting the plaster as I mixed it so I would have a neutral color to start with once we paint them.

I am a Newbie here and I have LEARNED Tons of info from so many OGR Members.

J Daddy

Can you please tell me what the purpose of a Hydrometer is for ?

I just looked it up and I can only find uses for Fish Tanks and Wine Etc.

Thanks in advance

SO, plaster of paris it is. How much time do I have to work with it?

Dont use plaster.It is to hard to work with.Go to home depot and buy a bag of regular Durabond 90.You have a full 90 min before it starts to set up..It will cost you about 10 bucks for a 20 or 30 lb bag.We use it in the drywall trade.Nick

I used the Plaster of Paris and some mixes I made soupy and some pasty.

I always let them dry overnight and made a fresh batch in the morning.

The thicker it was the faster I could pop the molds and keep moving.

There are so many different types of stuff to use.

So many recommendations it's hard to decide.

I am happy with what I used and the results are working out AOK for me.

I was pouring about 14 molds per batter of mix.

Nick, love rockstars 89. I meet my wife of 43 years at a rock festival in 1969 in up state new york. WOODSTOCK. That product sounds like just what Iam looking for . Thank's a bunch.PEACE

Hey Brian, are you having FUN.

FUN..FUN..FUN..

I told my Wife I hope we have as much fun using the layout as we are building it.

The Hobo's have Invaded my layout.

Stephen, another thing...make some of those molds half full..that will give you more to work with and make the rocks a LIL lighter and still have the SAME effect on the front.

I use plaster of paris for rock molds. Use warm mixing water if you are in a hurry. I also use it for formed in place rocks that I carve into sedimentary ledge, common here in the Hudson Valley, and I am sure, elsewhere. If you work with the plaster as it sets you will find it will fracture to reveal realistic rock like surfaces. Great material to work with.

Fred

I called US Gypsum and asked for the location of a local distributor.  I found a 50 lb. bag of Hydrocal type plaster.  I spent $14.00 at a building supply center, not Lowes or Home Depot.  I made seven latex molds using liquid latex from Michale's Craft store, and have been casting rocks and wall sections.  I used water with dish soap as a release agent.  The product I bought sets up a lot faster than the stuff in the milk carton.  I found that a 50/50 mixture of water and plaster makes a very runny mix that I can pour into a mold and allow a little time to fill four or five molds.  By the fifth it's already starting to set up.  I use a one gallon plastic paint pail from Home Depot and a paint stirrer that goes in a drill.  I use a wooden paint stirrer and a putty knife to scrape the sides to get the last little bit out of the bucket.  I keep a old bucket hit some water in it to clean up the paint pail and tools.  Don't wash this stuff down your drain. 

There was a recent post about Structolite, which I believe is a similar product to Durabond. Both are good alternatives to HydroCal.

You want what is known as a basecoat plaster.

Edit: Not for molds, see post below. It's not a quick set product. Thanks, Jim!

Stephen,

You do not want a slow setting plaster for rock molds. Use the slow setting products like Structolite and Durabond 90 for the basic hardshell, but not for rock caastings.

What you want is a fast setting plaster that will allow you to turn out the castings quickly and use the same mold over and over in a short time.

Although many use Hydrocal both for basic hardshell landforms and castings, I find it more efficient to select products with different setting times for each.

Jim

Hygrometer... sorry these can hang on the wall in the man cave and look cool too.

good luck on the cast molds... I have done quite a few... and have a lot more to do!

Thank you for the clarification, Jim. I am a foam board and Great Stuff guy right now and haven't ventured into the land of plaster products, yet.

What other commercial type products are quick-set. I have only used a cement type product for stucco patches that gives you about 15 minutes from mix to get it on, then it starts setting. Dry in about 30 minutes. Too nasty for modeling.

BTW. Don't use Wall joint compound. I used it for rock molds and unless you seal them, application of additional water will start dissolving them again.

I like the plaster of paris the best. It settles in the mold real nice and picks up the fine detail with a few taps. I mix small amounts at a time and they only take about 4-6 hours to completely dry, depending on your humidity in the man cave.... 

Has anyone tried colored tile grout in rock molds?

...keep the rails polished...

Tile grout is too course.

 I've not done this myself but have been told it works pretty well...

When you are filling the mold with the product of your choice don't completely fill it.

Leave some room to insert some styrofoam packing peanuts into the mix. Don't press them all the way to the front of the mold or they will ruin the rock face effect.

Even if the peanut protrudes from the mold it can be shaved off level with the back side of the molded shape with a hobby saw or knife.

This will effectively reduce the weight of the mold and save some of the needed plaster so you can use it elsewhere.

Mark

J Daddy

Thanks for the reply on the Hygrometer.

I spelled it wrong that's why I could not find it.

That's not a bad idea to put near the Train layout.

I run a De-Humidifier all summer so I am in good shape. I also keep it at 55% Humidity and basement is dry and comfortable.

Thanks again

I found that the more water you add the lighter the rock.  I mix mine the consistency of tomato soup.  It dries solid and is lighter than the thicker mixes.

Good stuff.

Spackle!

I use Bragdon Enterprises geodesic foam and casting resin to mold my rocks etc. It is light weight, impervious to water and doesn't crack like hydrocal or plaster. Here is an area I did with his products.

Here is a photo of the rock face resin castings I casted with Bragdon molds and hot glued in place onto the blue insulation board.

Here is the finished area painted