hold-making: ingredients for low density?

[ashw_justin]

I've made a few holds for my home wall by mixing silica sand and polyester resin. They turn out ok but something is not the same compared to commercial holds. That something is that commercial holds are lower-density, most likely by virtue of some kind of foaming agent added to the mixture, which allows for gas bubbles to be trapped inside the resin. The result is more texture and a lighter hold.

 

Does anyone know what is used as a foaming agent, and how?

Edited September 16, 2005 by ashw_justin

[Thinker]

try sugar and champagne yeast.

[Dru]

or piss and vinegar

[ashw_justin]

try sugar and champagne yeast.

 

I wouldn't dare subject a living organism to the harsh chemicals involved in this process. That would totally violate my principles as a level 6 vegan.

 

I'm trying to think of stuff that can be mixed to generate non-toxic gas, forcefully. Unfortunately we never learn this kind of stuff in chemistry, too dangerous or something.

[sobo]

Send a PM to AlpineDave. He's pretty adept at making homemade holds, and I'm reasonably sure he's thought of this already. He posted a thread some time ago about making holds, and he linked to his website for much more beta than I cared to read. It's just a suggestion... YMMV

[JayB]

You could try sodium bicarbonate and acetic acid - or any other acid for CO2 generation - but the presence of one or both reagents would probably inhibit the polymerization reaction to some extent.

 

I think that most other reactions that yield a bunch of gas generate stuff that that's either toxic or explosive or both.

 

Where is CBS on this one....

[ashw_justin]

yeah toxic and explosive, something like that would probably do the trick...

[ashw_justin]

Does someone know someone in the biz? Maybe if I email metolius they will tell me how. Not trying to start a business here, just want to make some custom shapes.

[EWolfe]

MicroLight.

[EWolfe]

Just found it:

 

West Systems makes a Microlight Filler material that is designed for use as an easy-to-sand/shape filler.

[JayB]

If you could get your hand on some small polystyrene beads you could use them as filler. Applying acetone to the surface would rapidly dissolve the beads on the surface - after which you could just live with the voids and treat them as part of the texture or "paint" the surface with a sand/resin mixture to fill in the voids.

[ashw_justin]

If you could get your hand on some small polystyrene beads you could use them as filler. Applying acetone to the surface would rapidly dissolve the beads on the surface - after which you could just live with the voids and treat them as part of the texture or "paint" the surface with a sand/resin mixture to fill in the voids.

 

Ah but tiny voids are perfect for texture, actually that's more important than the weight savings... hmm that's crafty. I guess I would need them to stand up to the resin chemicals for about 30-60 minutes... testing is in order...

[JayB]

Let me know how it goes...

[cj001f]

By Silica Sand you mean something like Colloidal Silica/other fillers? If not check out your local boat shop and pick up some fillers. They also have wood powder which is nicer on the hands.

[alipneH]

Not sure how to make the resin "lower-density" but to give your mold more texture, you can use a block of floral foam and a drummal tool to shape the foam. Floral foam is that green stuff old ladies use to make those fake flower arrangements.

 

good luck on the project

[ashw_justin]

heh-heh... no, I just picked up a huge bag (100 lbs?) of genuine fine-grit silica sand for $7. Sounds like a trip to the boat shop is in order then?

[cj001f]

heh-heh... no, I just picked up a huge bag (100 lbs?) of genuine fine-grit silica sand for $7. Sounds like a trip to the boat shop is in order then?

I'm not familiar enough with the stuff to know how different the materials are (and a quick search didn't turn up good information). http://www.jamestowndistributors.com/to;ID;,Epoxy...Adhesives,Fillers.and.Thickeners

lists a bunch of the different types. The microballons may work.

[catbirdseat]

"A very common thickening agent Cabisil or Colloidal Silica, although pretty strong, is really not best for structural support. Use this when you need to fill for contouring.

 

West Systems makes a Microlight Filler material that is designed for use as an easy-to-sand/shape filler. It makes a mixture that looks like a chocolate shake and when mixed really thick, can create a formable gel. Great for filets!"

 

The microlight filler is also known as Microballoons. I believe Aerogel is another name for the lightest of colloidal silicas.

[EWolfe]

That's the stuff. If mixed with sand and polyester resin to a **certain** degree, you will have a production-quality hold.

 

edit: Of course your mold surface texture has to be just so, as well.

Edited September 16, 2005 by MisterE