DIY Casting... a few Q's?

[redneckmedic]

I'm about 90% all in for casting. Have just a few questions for those well read or seasoned casters.

Please comment, correct, or advise where you seem fit.

I found a NIB paint pressure tank, I'm going to convert it into a pressure/ vacuum chamber with a duel set of valves and gauges.

I will stabilize in an open container in the chamber. Is there any advantage to seeing the bubbles if I can watch the vacuum pressure? Granted my cactus juice container is tall enough to handle the bubble up.

Can blanks inside the chamber touch each other?

Polyester Resin vs alumilite.

Is PR and rocker acrylic style blanks basically the same thing?

I found PR at Hobby Lobby for $24, the same sized container at Lowes for $14. And they had a 3 quart for $34.

What effects PR cure time?
Tempature
Dye amounts
Over all thickness of blank....?

What effects brittleness of a PR blank?

Can I use this dye for both alumilite and PR?
Resin Obsession - Alumilite Colorants Complete Set of Eight (8) Liquid Pigment dye

What IAP vendors sell alumilite and PR, and dyes?

Is there an advantage of powdered dyes vs liquid dyes?
A chart for how much to use for color tinting?
Tempature and time for "baking" in a dedicated toaster oven.

Organic items that don't cast well or need to be stablized prior to casting I.e. sugar gum sticker ball.

Thank You for your time and expertise!

RNM

 

[jbswearingen]

Seeing the bubbles only tells you when it's stopped bubbling. This generally takes a few hours. So set it for eight hours, release the vacuum, and bake.

The blanks inside the chamber can touch safely (I'm assuming you mean for stabilizing).

US Composites sells PR (Silmar 41) for $37/gallon plus shipping. It comes with the catalyst.

I don't know that Rockler's blanks are identical, but I believe they are a PR.

Yes, all those affect the cure time. Heat causes the curing. Dyes can affect it, but they vary in their effects. The thicker the blank, the faster the cure, as it gets hotter faster.

Too much catalyst will make your PR blank brittle. It only takes a little (as in drops) of the catalyst to cure the blank. The extra few hours of waiting for the smaller amount is worth having the slightly softer (and less brittle) blank.

That's all I know.

 

[Kenny Durrant]

I agree with Brad. The only thing I would add is that three drops of catalyst is the magic number for me. The main thing with pr resin is it only has a 3 month shelf life, so silmar41 says. I had trouble wth Castin Craft with snake skins and the Silmar 41 worked great. I still use the C.C. for other casts with no problems but be careful about how long it's been on the shelf. As far as seeing the bubbles during stabilizing, when the bubbles stop you know all the air is out. Good Luck Kenny

 

[ianjwebster]

Hi there - I've only cast half a dozzen blanks so far; so I am definately not an expert. I havne't used PR; only Alumilite. First time I used the Alumilite Clear and was dissapointed with the results. Kindly of 'cloudy' looking and lots of voids / airbubbles (I used a pressure tank). Then I tried the Crystal Clear; much much better. As it says, crystal clear and no bubbles / voids. Again, I have not tried PR but I like Alumilite beacause
a. No bad smells
b. Ready to take out of the mold in about 20 - 30 minutes
c. No need to bake afterwards
d. Really easy to turn compared to the commercial PR blanks I have purchased.
On the down side it looks like Alumilite is more expensive.

Just my 2c's worth.

 

[its_virgil]

I found a NIB paint pressure tank, I'm going to convert it into a pressure/ vacuum chamber with a duel set of valves and gauges.You can use the same plumbing for both the vacuum and pressure. Gauges that register both vacuum and pressure are available.

I will stabilize in an open container in the chamber. Is there any advantage to seeing the bubbles if I can watch the vacuum pressure? Granted my cactus juice container is tall enough to handle the bubble up.

Can blanks inside the chamber touch each other?The ones I have stabilized touched each other.

Polyester Resin vs alumilite.Depends on what you want to cast. Each resin has its good and not so good uses.

Is PR and rocker acrylic style blanks basically the same thing?I would say no. I have purchased blanks that were labeled polyester resin but they were not. But, it depends on what blanks you are talking about. They could be blanks made using polyester resin.

I found PR at Hobby Lobby for $24, the same sized container at Lowes for $14. And they had a 3 quart for $34.Polyester resin is prepromoted which means that catalyst has been added when manufactured. This means polyresin is curing as it sits. I have been told that poloyresin has a shelf life of anywhere from 3 to 6 months from the time of manufacture, not from the time of purchase. The MEKP we add gets the finalm curing chemincal reaction started. I would not purchase resin from any place except a supplier where I know the product is fresh.

What effects PR cure time?Ambient temperature, amount of MEKP added, amount and type of dye used, age of the PR, age of the MEKP, other stuff mixed into the resin such as shredded money or other materials, thickness of the pour, probably other factors. Thick pours should be done in several pours. The amount of heat generated and how fast it can be dissipated is also a factor. Too much heat can cause the casting to have fractures or fissures.
Tempature
Dye amounts
Over all thickness of blank....?

What effects brittleness of a PR blank?It has been reported by several that the amount of MEKP used can affect the brittleness of the casting. I will leave it at that.

Can I use this dye for both alumilite and PR?There are too many successful reports of dyes that will work on both either. I would only use byes or colorants sold by my PR supplier. Mica powders are excellent to color polyresin. Coastal Scents seems to be the go to place for mica powders. I don't do much color casting so I just purchase PearlEx powders locally. I have no comment on your link. Most polyresin and alumilite suppliers sell dyes and they even have starter sets.
Resin Obsession - Alumilite Colorants Complete Set of Eight (8) Liquid Pigment dye

What IAP vendors sell alumilite and PR, and dyes?

Is there an advantage of powdered dyes vs liquid dyes?The color casting I have done has had best results using mica powders. I have not had a pour fail to cure using mica powders but I have using liquid or paste dyes. I must say that one of my best blanks was colored with India ink.
A chart for how much to use for color tinting?
Tempature and time for "baking" in a dedicated toaster oven.Both polyresin and alumilite will cure without using an oven. Some post cure polyresin using a toaster over but polyresin has a flash point of around 90 degrees. What ever you choose to use I would suggest reading the MSDS sheets.

Organic items that don't cast well or need to be stablized prior to casting I.e. sugar gum sticker ball.Can't comment. I only cast snake skins, labels, shredded money and coffee beans. Others will chime in hopefully.

Thank You for your time and expertise!For my time you are welcome. For my expertise(LOL), if I have any, you are also welcome.
Do a good turn daily!
Don