Some free IP from me: this post is released under v3.0 of the GNU GPL
http://www.gnu.org/licenses/gpl.html(Can you even release IP under a software license? Who knows, but anyway. This is free, as in beer)
Someone mentioned "(standing in front of volatile carcinogenic chemicals)." From this comment I can conservatively deduce that the holds in question are made of polyester resin and some type of filler.
Firstly, polyester resin holds mostly suck. Why? you ask
Cons:
1. Polyester (a.k.a fiberglass) resin is, as above, volatile and carcinogenic. If you get the amount of catalyst added wrong, it very successfully self-combusts. If you breathe the stuff too much, you die early. It smells, a lot.
2. Polyester resin is heavy. Not a problem you say, you bolt them to the wall right? Yes. But from the second you start pouring into the mould, the resin starts sinking to the bottom, pushing the filler out of the texture that you've got in your mould and leaving only resin in the textured surface layer. Ever notice that the hold surface (skin side) is slightly shiny but the back of the hold (the flat side) has, what looks like a better mix of filler and resin? That is because of the density difference between the resin and the filler. The filler 'floats'.
3. Polyester resin has a natural glossy/shiny feel to it - I guess that's why the use it to build jetskis right?
4. Polyester resin is, when cured, lank hard but also very brittle. You've seen them shatter when they fall or crack when over-torqued.
5. Cures slow in comparison to other resins (hours vs mins) - giving the resin/filler mix more time to separate.
Pros: Cheap
So instead you use Polyurethane resin. Pros:
1. Hard
2. Strong
3. Not so poisonous
4. Not brittle (it squeezes when you overtorque instead of cracking - the washer ends up waaay bent before the hold breaks)
5. Lighter - so closer in density to most fillers, meaning the filler/resin mix stays more mixed while the holds goes through early curing.
6. Has a natural matt texture
Cons:
1. Expensive
2. Pricy
About moulding, casting, etc process in general:
These guys sell their process ebook for $20. Worth it I reckon:
http://www.threeballclimbing.comAbout fillers:
To minimise resin costs (its expensive yo), nearly every hold manufacturer (the ones that don't want to go bankrupt anyway) use a filler - an inactive powder/fiber - added to the resin mix to add volume. Light fillers 'float' on the resin, heavy fillers give better texture. Cut fiber fillers add tensile strength (and f*ck up your lungs, don't breathe them in). There are hold producers that are making pretty good quality holds in SA, from polyester resin nogal. Good texture without the shinyness. I think they use a higher density filler that doesn't float on polyester resin. If you use polyurethane resin you can use lighter fillers. I have had great texture success with glass bubble fillers (don't breathe that either).
About texture:
The best I've found is not the green 'oasis' or flower shop foam, but rather the rigid polyurethane foam that they use for thermal insulation. There is a company in Apex, Benoni called Rigifoam that manufacters rigid PU foam for insulating truck bodies and cold rooms. They have a pile of this stuff (offcuts) behind their factory that they'll give you loads of if you ask them. They throw it away. This stuff is the real deal - this is what oversees companies sell as 'hold shaping foam' - check out
http://www.threeballclimbing.com/climbi ... g_foam.htmAbout moulds:
Make them with pouring silicone. Bubbles aren't your friend.
Want to try your hand? It's not that hard. Loads of stuff on the interwebs...
http://www.alumilite.com/howtos/Molding ... gHolds.cfmWhere to buy stuff? Company called Techoresin (also on the East Rand) sells all different types of resin, silicone, casting supplies and products. Also good is AMT composites - their sales guys are very helpfult with info and application details. Get cheap latex gloves from Dischem, the shit (especially the dyes) sticks to your hands like anything.