Was at the local masonry store and the owner told me to take as many of these cobblestone cultured stone pieces as I wanted 'cause they were defective and getting destroyed. Needless to say, I took quite a bit.
What I was thinking about doing is framing up a small retaining wall (box) and covering the sides with plywood. Next, I'd slap clay on all the sides and then embed the cultured stone into the clay. For the mortar areas, I'd just use a wisk and small stick to make the mortar look irregular.
For the mold, if I'm going resin/fiberglass, what do I need to do with the stone and clay (and WHAT kind of clay should I use). If I'm going to go with a latex layer backed with fiberglass, what would I need to prep the stone and clay with prior to using the latex?
Del
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My vote for this project woule be to use silicone or 2 part urethane elastomer for the mold, with a fiberglass support jacket. Latex I would avoid because of the gripping properties it has on porous materials. I've had to use pliers and a LOT of force to remove latex from sealed rock before.
Your ide of making the retainign wall etc is right on the money. An oil based sulfur free clay such as "Klean Klay" is your best bet. The oil keep it from crackign it and drying out and prevents mold materials from bonding to it. The sulfur in some clays can retard a proper cure of certain silicones. Klean Klay is an inustry wide standard. It can be found I believe at dickblick.com as well as other outlets. A google search should yield good results.
Alumilite.com is a good place to search for silicones.
Industrialpolymers.com is a good place to search for flexible urethanes.
polyester resin and fiberglass mat can be found at boat building places, auto departments of deprtment stores or from specialty plastics companies. COntact a hot tub builder or boat builder and they may be able to give you asource for resins and glassing supplies.
and I'd need a bunch of Klean Klay for the project given the size of the wall. Any other oil based sulfur-free clay recommendations? I'm going to be covering a 18" x 48" area.
not sure if clay will hold the stones on to the wall. I would just do the real thing with actual mortar and all.
use construction adhesive to glue on the stones then keep a dry batch of mortar (not actualy dry just stiff) handy and fill in your joints as you go. the joints will be difficult to get perfect with irregular stones, so let it start to set up and make uniform with a unsharpened carpenters pencil. joint depth is important to get uniform for rough stone work 3/4 is about as deep as I would recomend 1/2 would probably look better. to do this with clay might result in smearing it on the rocks on the way into the joint. if you use mortar do it by hand with latex gloves. If you have never done stone work, one off rock or fat joint can become the focal point of your wall, so lay it out flat and dry first, cut all your cuts and make sure it all fits before you start glueing or embeding in clay. for cutting you get the best look with a 4.5 diamond wheel in a grinder. fiberglass for a mold will probably bind in the nooks of the rocks. you could always make the wall out of a sheet of foam, cut out your rock shapes and sand the edges round then glue the foam rocks to the plywood.
and for clay Monstermakers.com sells 20lb blocks of non sulfur oil clay.
good luck
The stone isn't your typical masonry block of irregular height and width. They're probably about 1.5" thick at most and some 8-12" long with fixed heights. Not heavy as a solid stone...feels like hydrocal and ground stone filler. It was free for the taking. The nice part about it, they're all squared up and different sizes so it'll make a nice pattern suitable for my needs with no grinding/cutting necessary.
The reason I was looking to go the clay route was to eliminate fixing these rocks permanently. I want to make the mold and a jacket, then tear the foundation piece down for another item (small column).
Based on what I've heard here:
Latex for stone/clay casting, even if the rocks are sealed may pose problems when trying to unmold.
Fiberglass might get stuck on the rocks (even if it's just a jacket?)
The only polystyrene sheets we have on the west coast where I am is the high density white board (which is not unlike bead board) and my sculpting skills suck.
You don't need to be a sculptor.
Nature already sculpted the piece for you! All you need is that texture pad and you are set... Trace those broken pieces if you need to to make a template if the shape of each brick is too much like sculpting.
Then do all the other steps I laid out in the other post. All your answers are right there if you do the leg work. Did you go to dickblick.com? They have other clays available there. Did you go to Industrialpolymers.com? They have flexible urethane mold making materials... Im not talking resin OR foam - I'm talking 2 part mold making urethane. And yup - you are going to need a lot of clay - and yup - it's an expense - this is why things like this are called businesses - LOL! And YUP - you are probably gonna blow a buttload of money trying to learn how to do all this stuff. Such is the nature of business.
If the lack of knowledge and prohibitive cost of experimentation to gain that knowledge is too much.. then it's probably a good time to start thinking about contracting an experienced professional to make the pieces you need for you.
I've seen and read a number of how-to posts and websites in a number of places but none in particular to this job's specific needs...and coming from zero knowledge in this arena, I posed a question or two to help me out.
I don't want to go the texture pad route. I have the prefab stones here that I got for free (as mentioned in THIS thread). Was HOPING to embed them into the clay wall and do up a job of fake mortar WITH the clay.
Since this is a vertical application, I'll need something that can be painted/brushed on. If urethane is my best mold solution, so be it. I'm guessing that it's essential to do the resin/fiberglass jacket too since the urethane wont give it enough support.
Don't kick the people that are trying to learn. You have knowledge you were willing to share, and I thank you for that, but talking down to someone never helps.
Feel free to ignore my future posts if you believe your replies have been falling on deaf ears. I don't want you thinking you've been wasting your time helping me out.
Del
I have worked with the fake stone before and you do need to cut it sometimes. you will wind up with irregular mortar joints. and I dont think it will stick good enough to the clay just by pressing it in. by all means try but it is much cheaper for a $5.00-$8.00 bag of mortar and a few tubes of adhesive. Just like molding, stonework is one of those things you do not get right on the first shot. I have seen and had to fix some real crappy stone work. just to make it worse, the smaller your piece, the harder it is going to be to make it look right.
smoothon makes some urathanes of different hardness. www.smooth-on.com
you might want to get some samples and experiment on a small scale say one rock before you go balls to the wall.
I still recomend doing it with real mortar.
I just see a posibility of getting clay all over your stones, 1 1/4 and you have to fill in at least 3/4 of an inch. the clay has a good chance of getting rubbed off in the sides of your joint.
can I break this wall down and reuse the stones with little problem (eg, mortar stuck to the stone becoming too difficult to remove.)
Del
The only part that I was seemingly upset about is that a lot of the answers were already detailed in the other thread - thats all... about materials and such.
Mortar is rock solid and will hold your piece very tight UNLESS... it is anchored to something NOT solid. Carve your basic shape out of foam (even bead board will work for this). Coat with white glue then sand to give it tooth, then mortar and set over that. When it comes time to take it all down, the foam will tear itself apart leaving you with a tile that has mortar on the back. It will work - but then you have to remove that mortar - generally with a chisel or angle grinder. Often it will lead to the tile breaking.
Another option is simply to use a glue gun with low temp glue sticks. Warm your tiles first - then squirt melted low temp glue and stick onto your form. When it comes time to remove the tiles - simply heat them up with a heat gun. Wipe the glue off of the back with a rag and go again...
I suggest the low temp because excess heat of cultured stone can cause it to warp and give off all sorts of nasty fumes. I suggest warming the tiles first because applying the glue to a cool surface will prevent it from bonding as efficiently.
My question now is... why does it have to be vertical? make your originals flat and mold them - you can position the cast any way you like thereafter. If I were molding a pillar or column and had the option of laying on it's side I would DEFINATELY lay it on its side. Doing it this way will help you adhere your tiles easier... make applying your mold material easier.. and will be HUGE assitance when laying your fiberglass on. Trust me - you do NOT want to fight gravity with sheets of resin soaked fiberglass - it's a huge pain in the keester.
Another idea.. make molds of your pieces you got for free and cast enough to do your other projects. That way if you do use mortar (tho I think it's overkill for a project like this) you don't need to reclaim the parts afterwards - simply cast up more as you need them. Years from now you could still be adding to your set of props and maintain consistency in appearance as you will never have to go searching for similar size shape and texture etc.
The way I was planning to set the form up was to have clay on 2 sides (long side and short) so I can do photo shots straight on or with the retaining wall at an angle so I capture 2 sides of it.
Some of the cultured stones I got are L-shaped specifically used for corners (to give the illusion that the stone has depth and aren't merely a vaneer.
I could do each side separately, but then at the corner where one would expect the stone to have been solid, it will show it wasn't (Unless we're talking about touching up the mold afterwards to fill in the indentation at the corner the whole 18" high.)...damn. I'm not sure that was even clear. Basically, I'd have to figure out how to do touchup to make the stone look solid at the corner for a wrap around effect.
Flat WOULD be much easier.
Del
All you need to do is cast a spearate corner piece. Have 2 flat walls that sorta fit into a corner section. Imagine this... Build your wall, then follow your mortar lines and cut out the column of bricks that make up the corner. Only instead of actually cutting those corner pieces out - keep that corner separate when you are first constructing it. So to get your wrap around corner - build 3 simple shapes - the corner, left side, right side... Constructed properly - when the 3 pieces are joined up - you shoudln't be able to see the seam at all. The more rugged and natural your stone is the more it will camoflauge the seam.
it is not only for strength it is also for look and ease of construction.
even if you bought the rocks they would still only be 1/10 the cost of the project, so why have any chance of something going wrong in that 1/10th and ruining the other 9/10.
just my oppinion
I can visualize exactly how you're talking about doing it Raven, and it does make sense, but how do you make the mold? Since there are two sides that will need to be coated, should I just make a box slightly larger than it and section it off so my urethane pretty much only covers those two sides? (If you looked down at it, I'm thinking a square box with the corner piece looking like a V. Sound about right?
I'm going to have to show you a photo of this when done. :-)
To mold the corner piece - apply your urethane over it to make the mold. Since it is flexible, it will peel off that 90 degree corner. The jacket MIGHT hang up on you however. To alleviate this you need to design a 'break'. Coming right off the corner at 45 degrees - build a wall over top of the urethane. When you fiberglass - fiberglass up this wall to create a flange. Remove the wall and then glass the second side. Drill through the flange to bolt the pieces together. This techinque will likley have to be used for all your parts. A simple wall section will probably need breaks at every right angle to avoid locking up.
A good molding book - especially one dealing with fiberglass molds and parts would be helpful here.
I'm putting an order for that book you mentioned in the previous thread right now. Guess I'll wait till it arrives to order all my stuff.
I was looking at all those stone granule/powder add-ons from the links provided, and most seem suited for countertops and finished materials...What about for folks that are trying to duplicate gritty sandstone/limestone and whatnot? A mix of different stone powders?
Don't over think the process - you'll only get a headache - LOL! If you want to create sandstone - your gonna be hard pressed to get an additive better than sand right? Makes sense... so go to a hardware store and grab a big ole bag of playsand for like 4 bucks and your all set. Tint your gelcoat to the right colour and add the sand in it. Don't use construction sand as it is more yellow than playsand and won't take colour the same way.