[walter]

Dear Walter,

I do not do aesthetics...

That black carbon thing really adds sportiness- I'm gonna order a kilo..

[Zumba]

I definitely do aesthetics.

I just noticed the pigments list on the US Composites website. Thanks Ger for pointing that out and helping me spend money.

Hmmm... black, blue, or grey? Argh, the decisions!

Maybe red.

Wait a minute... I'm putting my E/G INSIDE the metal...

[ger21]

Wait a minute... I'm putting my E/G INSIDE the metal...

But you'll still know it's red.

[jsage]

I'll take a wild guess and say anocast might not have started with big industrial castings. If so they took their technology/process and applied it here.

If that is the case than the surface serves a purpose in molding but also provides some beauty, what's that word again anaesthetic. I know what that means. It makes you drool or something like that ; )

Hmm, don't know if it is the same link but interesting.

http://www.rockwellautomation.com/an...df/Anocast.pdf

Well I guess they did start with industrial castings. Probably at least a 3 step process. They also mention the special non metallic sauce... I mean additives.

[Geof]

The black was probably not much to do with esthetics but because it was part of a machine for making photo-offset printing drums or plates or something like that.

[jsage]

So how much does the basic cost per pound again. How many pounds to a cubic foot?

[lgalla]

I buy carbon black.Manfactured by the Cabot Corp from the Canadian distributer
LV Lomas.Grade Monarch 800 produces a fantastic black with epoxy.I think it is about 3to 5 dollars a pound.They are a huge industrial supplier and give no hassel for 1 bag orders.A sample request would be enough for most projects.They also have ground silica sands in many particle sizes.I would stay away from liquid pigments as they can effect the cure and strength.
Black granite is available and duplicates the look of granite.Upper Canada stone has beautiful black granite but only supply railcar loads.Am still looking
for a low quanity supplier.It's out there.
I think Moglice uses graphite epoxy for their way material.
On epoxy gel-coats good luck.Ever notice the suppliers don't have one?If you coat your mold with thick epoxy it will run off the verticals.If you thicken it to peanut butter viscosity,It will run to the bottom of the mold.The self leveling of epoxy is a good thing but not always.Sorry I don't have an answer for the problem.
On spraying epoxy.DON'T unless you have a spray booth,air supplied respirator and body suit.People are under the impression epoxy is safe as it contains no solvents.Yes it is safe fore E/G mixing but not for spraying unless you meet the 3 requirements above.
Larry

[Zumba]

Jsage,

I'm estimating 30-40 cents per pound, with a density of roughly 0.1lbs/ci or 170 lbs/cf. Averages out to $60/cf.

Much cheaper than using metal billets or iron castings. Of course, if you screw up, the resulting material is worthless whereas billets can be reused.

That's what practice is for. I'm going to practice making E/G bricks and decorate my garden!

[martinw]

.They also have ground silica sands in many particle sizes.I would stay away from liquid pigments as they can effect the cure and strength.

On epoxy gel-coats good luck.Ever notice the suppliers don't have one?If you coat your mold with thick epoxy it will run off the verticals.If you thicken it to peanut butter viscosity,It will run to the bottom of the mold.The self leveling of epoxy is a good thing but not always.Sorry I don't have an answer for the problem.
Larry

Dear Larry,

I may be quite wrong, but I would have thought that the ground sand route would be better that the pigment one. In order to increase the strength of the surface of the article, while still being able to cast-in fine details, I think a fine aggregate like sand might work.

As regards the problem of vertical surfaces, I absolutely take the point that you do not want the "gel coat" to be too runny, nor do you want it to be so "thick" that you can't mould fine details. I'm guessing, but isn't there a consistency somewhere between these two extremes that will do what we want?

Best wishes


Martin

[ger21]

We made some cantilevered counter tops at work where we Epoxied Steel reinforcement into particle board tops. They were small service counters, where people would be leaning on them. We used West System 404 or 406 (don't remember which, but it's on my desk at work). Anyway, you can mix it to a mayonnaise consistency which won't run, but you'd have to squeeze it into to tight spots, but you could probably brush on a thin coat, but it might not be terribly even.

[ger21]

There was mention of vacuum pumps early on in this thread. I just got a "new" Gast rotary vane pump from Surplus Center for $89. Even though it was "new", it was a little beat up, but didn't look used at all (more like it was dropped). Wired it up yesterday and it worked great. Swapped it for my venturi system, and it quickly pulled 26" Hg.

Only problem for some would be that they are 220V only. I'll be using it for veneering and a hold down system when I get around to it. A similar 110V model is available from McMaster Carr for ~$350, so it's a great deal if you have 220V power. I plan on picking up another for a spare. They have about 1000.

[martinw]

I'll be using it for veneering and a hold down system when I get around to it. .

Dear Gerry,

I have a small medical vacuum pump which I've used for laminating and veneering (not hold-down work) for quite a while. You will wonder how on earth you managed without it once you try it.

Best of luck

Martin

[ger21]

Martin, I've been using a venturi system for veneering for a few years now, but was getting tired of listening to the compressor running.

[jsage]

Zumba,

Thanks, that is definitely reasonable. Yes I think it has other uses as well like making veneers less brittle.

Standard epoxy does break down pretty quickly in direct sunlight something like a year or 16 months, but your only talking surface in a densely packed aggregate.

I was thinking for exterior applications I could use a thin layer of uv stable clear epoxy in a female mold or similar depending on finish. Acrylics discolor as well.

[martinw]

Martin, I've been using a venturi system for veneering for a few years now....

Oops! Sorry Gerry.

Best wishes

Martin

[jsage]

I was experimenting with key word searches and found the following link which gives some relevant info though certainly not step by step.

epoxy quartz vibration dampening industrial precision castings additives non metallic


http://www.velocityseriesinsider.com...11%20November/

Another Issue that has some relevance.

http://www.velocityseriesinsider.com...12%20December/


This looks like a good reference that requires payed subscription that comes up under polymer composite

http://www.4spe.org/pub/journals/index.php


BREAKTHROUGH POLYMER FINISHING TECHNOLOGY

I found this in the references of a michigan state study. Used this as a search and came up with this.

http://www.vitroco.com/discovery/polymer.pdf


Long treatise on sound dampening composites
http://www.skk-banjaluckapivara.com/...composite.html

[lgalla]

Martin the epoxy gelcoat consistancy is difficult to acheive as just before gel epoxy gets very thin and runs.Boats made with epoxy usually have a polyester gelcoat.I forgot epoxy is not UV stable and will yellow with age.Some pigment may be a good idea for uv blockage.
A good thixotrope is Cab-o-sil,which may meet you requirements for hardness.It is a air floated silica.High loadings to jello or paste consistancys may work for epoxy gelcoat.I will try to explain the product.
Mixes that look to thick will flow ,when you apply some force eg.brushing or spraying,the viscosity goes down,then sets back to its origional thickness.
Sorry it is hard to explain.A technical ex may help.
Fumed silica in resin has longchain hydrogen bonds which are easy to break by lets say brushing.After the force is removed the chains re connect and the mix returns to thixotrop.This stuff is TOUGH.Almost impossible to sand.
A food grade of this is in ketchup.You know it won't come out then suddenly,
Gloop to much.My EX-plain-a-tory skills are poor.Please ask if you are not clear on the subject.
Regards
Larry

[jsage]

Igalla,

I don't know what the right "gel coat" would be in this case or if it should be done post mold. In know gel coat isn't great for you and a hardened paint which name escapes me is particularly bad for you. I believe it is an isocranulate or whatever that name is.

I mentioned clear epoxy because there would be no compatibility issues. System three has a couple clear solutions. The clear epoxy has an extremely long cure rate which I would think would prevent the "exothermic slide" ; )

http://www.systemthree.com/p_clear_coat.asp

There is also a catalysed clear WLPRU? urethane which is compatible with epoxy. The catalyst can be applied as a final coat.

http://www.systemthree.com/p_wr_lpu.asp

Frankly I'm starting to side with Martinw, the hell with the aesthetics, lets just get the formulation right and engineering right to begin with. My CNC machine doesn't have to look like it is made from granite. Just needs to be a significant improvement from steel construction and relatively easy to fabricate


Best,
Mike

[ger21]

A year or 2 ago I did a lot of research into composites and molding. Found that a lot of guys building model planes spray the paint in the mold before doing the layups. Pre finished parts. That System 3 urethane would probably work fine for a "gel coat". You're just trying to keep the mold release from being scraped away.

[Geof]

...I believe it is an isocranulate or whatever that name is....

I think isocyanate is the word you are looking for; Crazy Glue. Also used in other formulations.