Friday, August 20, 2010

Molding And Casting Rocks

My last post dealt with creating rocks by hand modeling. So this time I thought I'd touch on a couple ways of making rocks by casting them from molds.

Sometimes while walking the beach I'll find a rock or small piece of driftwood that calls to me. I don't know where I'll use it but if it is the perfect scale for using in a sculpture I'll hang onto it.

On occasion I'll make a mold of these found rocks. The rock I'm holding in the photo had barnacles adhering to it which I thought would make an interesting addition to a marine diorama.

Generally the materials I'll use for simple molds are liquid latex or 100% clear silicone caulk. For my mold separator I take a glass baby food jar and put a blob of Vaseline petroleum jelly in it.

To this I add a few drops of Naphtha. I keep adding the fluid and stirring the mixture till the Vaseline is thinned down to a brushable consistency.

If the model isn't too intricate another economical separator to use is neutral colored shoe polish. You apply it to your model and then buff it with a soft cloth.

On rocks I stick with the Vaseline mixture and just take an old bristle brush and apply it directly to my model.

After the separator I brush on multiple coats of liquid latex. Usually about 8 coats though that can vary due to the size of the mold. When the latex has cured I apply a bit of my separator to the outer surface of the mold and make a mother mold which will support my flexible latex mold. Sometimes on small molds I'll use Apoxie clay to make my mother mold. On larger molds I'll use Bondo Auto body filler.

Once the mother mold has hardened it is removed and the latex mold peeled away from the model.

The above photo shows a latex mold of the rock and its two piece mother mold. The rock was cast using a mixture of casting resin and Bondo auto filler.

The yellowish casting in my hand was made using Polytranspar Liqua-Cast from Wasco: WASCO -- Wildlife Artist Supply Company

When I don't have time for the multiple coats required for building up a latex mold I'll use 100% clear silicone caulk.

I'll use the same Vaseline mold separator on my model and apply a small amount of the silicone with a caulking gun.

Using a disposable brush I smooth the silicone over my rock model. Because the silicone is so thick this technique doesn't work well on highly intricate models. But for this river rock it worked fine. I try to get an even application of about a 1/4" thick.

The mold I'm holding is made of silicone caulk with a two piece mother mold of Bondo Auto filler.

When it comes time to cast the molds I'll brush a bit of separator in and use Apoxie Sculpt clay pressed carefully into the mold.

Other times I'll cast a mixture of casting resin/Bondo into the mold to make my rock. This is a picture of a small latex press mold and my cast rock.

In the photo below the lighter colored rock is Apoxie Sculpt while the darker one was made by pressing stoneware clay into the river rock mold. The size difference in the rocks is caused by shrinkage during the firing process.

Another option when it comes to making molds is to use the type of materials offered by companies such as Smooth-On - Mold Making and Casting Materials for a World of Applications!

The photo below shows a mold of the same barncle covered rock made using Smooth-On rubber in a plastic container in one pour.

After it cured the mold was partially cut apart to free the model. This method leaves much less seam line to clean off your casting then a traditional two piece mold would.

Saturday, August 14, 2010

Seeing Light At The End Of The Tunnel

I'm pleased to say I'm approaching the finish line on my Skull Island cavern project.

One of the remaining tasks to complete was creating some loose rocks for the interior.

Whenever I'm working with Apoxie clay, mache or wood putty I will always make up rocks with any surplus material.

The collection of these rocks in the above photo on the left are textured to look like marine rocks. The batch to the right are more like ordinary rocks. Sometimes I'll add a stick into the rock as a handle for when it comes time to paint them. For my skull island rocks I cobbled together a few of these leftovers, added some carved styrofoam and finished molding them with Apoxie Sculpt clay.

By modeling these rocks by hand using the same technique to texture the clay that I had on the cavern I achieved a good match.

Here are the finished rocks painted and sprayed with Dullcote.

I thought I'd celebrate nearing completion on this project by having a nice seafood dinner!

After picking my wife up at work we drove to the nautical mile in Freeport.

The Nautical Mile Fish Markets

My favorite fish market on the mile is Capt. Ben's. While there I bought some salmon fillets, shrimp and a dozen Little Neck clams.

For our dinner I made salmon cakes, spaghetti with white clam sauce and garlic shrimp. My wife made a green salad and a toasted garlic bread with melted mozzarella cheese. That bread was soooo good!

Sunday, August 1, 2010

And The Winner Is!

The winner of the skull from July's giveaway is Nitebyrd. Congratulations Nitebyrd if you'll email me your address I'll get the skull mailed off to you.

I spent most of Saturday working on the miniature cavern. Early afternoon I called it quits and took my wife and mother to the beach.

Soon after we got there and we saw a pod of dolphins chasing something close to shore. This video clip a beach goer posted on Youtube shows one leaping out of the water: YouTube - Dolphins about 100 yards from the beach (Long Beach, NY) The group that passed our beach came as close as the tip of the jetty. It was pretty cool to see!