Fake Lava Rock....Advice Please!

Does anyone have any pictures and advice on homemade backyard rockwork?

Richard and I are right in the middle of creating some fake lava rock raised planters and other things for the backyard. Does anyone have experience with what type concrete mixtures work best?

We're creating the shapes by taking metal lathe and sculpting it around all kinds of junk we've got, like old concrete blocks and pieces of old metal junk.

We've found the most difficult part is getting the cement to stick well to the verticle surfaces, it just falls off or slides through the lathe. We tried a mix of one bag of regular cheap concrete to one bag of regular stucco with about a bucket of peat moss thrown in makes it stick better - it thickens it up quite a bit and it's more like clay. It seems to be hardening okay, but it's taking like a week for it harden up really good as opposed to straight concrete that hardens up over night. Next we're going to try adding some mortar to it.

For the texture, we tried the rock salt idea and also the crushed ice cubes mentioned in a post here. The ice cubes kind of mushed up the surface and didn't work out too well. The rock salt worked pretty well, but the detail is very small. We're finding that making the lava holes with little sticks of different sizes works pretty good, gives a more theatrical lava rock kind of look, more like old fashioned fake rock like old Adventureland or something. Looks cool.

We stuck some seashells in here and there also. I think for color, we're going to try just spraying on some black paint, probably exterior latex. Any advice on color?

We'd love to see some pictures of what anyone else has done or any tips to give us inspiration!

Mahalo!

I've never tried anything but I'm interested in seeing what works for you. Also, I wonder since pool companies use gunite, maybe that is a substance that might work either alone or mixed with something else. Keep us posted.

pariartspaul please post some images when you can...I would love to see what you 2 come up with. I have an idea to do something eventually in Lava around our spa, I haven't decided if I will use the real stuff or try to manufacture something like what your trying to do. A lava wall is going to be my next project for the lounge. Johnnie V. has posted pictures of his lava bar he's made with insulating foam sealant. Although I don't know how it would hold up outside in the elements. Sorry I don't have any tips to help you out, I haven't begun the lava projects "yet". OH! if there were only more hours in a day. Goodluck!

Concrete mixing can get to be quite a science. For vertical surfaces, you want to get the mix to just the consistency that it will hold its shape when a trowel is dragged thru it, but is still wet and spreadable, like canned cake frosting. Also be sure to let regular concrete & stucco sit after mixing for 15-20 minutes before you start to work with it.

For texture, experiment with different mix ins that will dissolve or quickly break down. Rock salt works well; ice cubes tend to melt too quickly and dilute the concrete, creating muddy pockets. I've had luck with things like croutons. Try spreading out rock salt in a thick layer, spray lightly with water to get it to all stick together, allow to dry, and break into chunks for a heavier mix in.

I haven't done any faux lava rock in years, but regular rock salt & the homemade chunky rock salt always seemed to work the best.

There's lots of color additives for concrete... its nice to tint the actual concrete mix & just accent with paint. Then you won't have to worry so much about touching up chips & fading paint.

[ Edited by: Traderpup on 2004-03-21 22:04 ]

Thanks for the ideas traderpup - when you said croutons I thought, 'but they are square'. Then I got thinking hey what about cereal!? Kix, rice crispies and that puffed corn stuff might be just right! I think they sell those bargain brand max pack things in the big plastic bags. I'm going to try it and I'll let you all know.

Someone must have some pictures out there! Please......

Have you tried wetting the rock salt & clumping several crystals together to make larger crystals? Try putting the rock salt in a plastic gocery bag & spritzing it with water from a spray bottle. You can then shake up the bag to get the crystals to stick together in clumps.

What about Salt Licks? You can buy salt licks in most feed stores, just smash 1 up with a hammer to make chunks.

Have you tried rock candy? you can get large chunks of rock candy @ many candy stores. Or you can wet sugar cubes to round off the corners & edges, & stick some of them together to make bigger aggrigates.

Rev. Dr. Frederick J. Freelance, Ph.D., D.F.S

[ Edited by: freddiefreelance on 2004-03-22 13:26 ]

Just an update - we finished off one of the planters and we've done some more experimenting. We found that just hand carving the lava texture really works out the best. First we laid on the mud, then took a whisk broom and patted it all over for a nice overall rough texture. Then we hand sculped the little holes using sticks of various sizes. It worked out great.

For paint, we used black exterior latex and it covers good - I have one of those big sprayers from the Home Depo so we sprayed most of it on, then went in by hand with a brush to get some of the edges and detailed areas. Looks like real lava rock.

We're on hold this weekend because Richard had to go to L.A. and I'm working on sign orders. We
still want to put some flagstone edging at the base to give a border between the rock and the lawn so it will be easy to mow the grass around it. And we're going to play with some more colors - maybe some drybrushed hilights here and there. And then we're going to hot glue some seashells for the finishing touch.

So we'll post some pictures when we finish - probably next week.

[ Edited by: pariartspaul on 2004-03-28 08:59 ]

Aloha Pariartspaul,
When you work with stucco, its best to do it in two stages. The first stage called the brown coat fills in the stucco mesh. Before this coat sets up comb it or scratch the surface all over to create a bonding surface. After this coat has cured go to the color stage. The second coat is called the color coat and this batch of stucco is usually colored with a powdered color product. Lightly wet the brown coat surface. When that surface is no longer wet but just moist spread or trowel on the color coat. When this begins to set up texture your surface with combs, tools etc. The best salt to use is the kind they use for water softening. It resists melting.
Tikiboy