Ultra sonic or Pressure vacuum pot

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le_skieur

le_skieur

Member
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Sep 29, 2010
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Hi,

I would like to cast my own resin blanks like feathers and I look for opinion regarding method of casting. I know some are using Ultra Sonic and some are using pressure vacuum pot. I am in USA for the next month so I have the opportunity to get the right product for my future needs.

Thanks for helping me in my choice, comments are welcome
 
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From what little I have found about the ultrasonic, it is used to prep the rosin for mixing. The pressure/vacuum pot is for casting. I probably have it backwards, vacuum on Alumilite, pressure on PR , so check with Curtis http://www.turntex.com/ for more definitive info on Alumilite. With a good pot, you can use either pressure or vacuum.
Charles
 
I cast only polyester resin. I once used both vacuum and pressure to help control the problems caused by air. Now I use neither but I do use ultrasonics and heat. The ultrasonic unit I use has a heat function. Good luck with your decision. The type of resin you plan to use will impact your decision.
Do a good turn daily!
Don
 
Thanks guy's,
I maked my mind and I buyed a Ultra sonic for starting. I will go wil PR.
 
I bought the one with heat capability. Like Seamus, I heat for about 8 minutes, add in any colors, mix the catalyst, and pour. I also put in a pressure pot for about an hour or so and then remove. I believe I have had better results using the heated resin.
 
+1 on ultrasonic with heat. I used at least two (usually 3) 480 second cycles with heat. I, like others here, mix each of the colors I am using in a separate cup before heating.

The only "issue" with using 3 cycles is that the resin is very thin and must be molded immediately after removing from ultrasonic and catalyzing. Resin this thin will start to gel in less than two minutes.

While a little speed and caution must be observed when using this method, it yields bubblefree casting. This method works better for me than pressure or vacuum casting.
 
Would you mind expanding a bit more?

Are you just preparing the resin in the ultra-sonic "cleaner" and not putting the mold into the water bath or something completely different?

Assuming the mold just is surrounded by the water bath, do they need to be weighed down, or does silicon sink naturally?
 
arw01 said:
Would you mind expanding a bit more?

Are you just preparing the resin in the ultra-sonic "cleaner" and not putting the mold into the water bath or something completely different?

Assuming the mold just is surrounded by the water bath, do they need to be weighed down, or does silicon sink naturally?
Click to expand...

Many other heat the mold prior to pouring. I DO NOT heat the mold beforehand! I tried that a few times, and it was a disaster for me.

If you heat the mold in a toaster oven, the bottom of the mold gets hotter than the sides which caused me big problems.

If you heat the mold with hot water, it takes 30-45 seconds to get all the water droplets out of the mold (getting ANY water out if the mood is an absolute must with PR). With less than 2 minutes to mold thin resin, this is hard to do.

I use three 480 heat cycles because it removes the "timing guesses" as to when to pour each color into the mold. With resin this thin, you catalyze the first color and pour as quickly as possible, catalyze the second cup and repeat.

If you pour quickly enough, you still get about 15 seconds of toothpick swirl time before the blank begins to "clump".
 
I do put the completely molded blank on the running bandsaw table for about 5 minutes in case I got too aggressive in the catalyzing process.

There are two schools of thought on how aggressively to stir when mixing colors or catalyst. On school is to stir as fast as possible to "force" bubbles to the top.(this NEVER works for me).

The other school of thought is to stir as slowly as possible, thus not causing air bubbles. I prefer this method as I color the resin before heating. I can go as slow as I like to get a thorough mix. Thinning the resin eliminates ant mixing mistakes I may make.
 
In the winter I will post cure a gelling blank in the toaster oven for 30 minutes at 147 degrees ( where my oven works best).

Never leave a post cure in the oven, unattended. While I have found this to be relatively safe, should the oven malfunction there could be a risk of fire.
 
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PenMan1 said:
If you heat the mold in a toaster oven, the bottom of the mold gets hotter than the sides which caused me big problems.
Click to expand...


Two questions regarding what happened to your test :

1) what was your temperature set at when you tried this

2) Does your toaster oven have a setting for 150 degrees?

The reason i ask if because i use my toaster oven at 150 maybe 148(even though there isnt a mark for that temp{148}) and I dont have any problems with my snakeskins burning or shriveling on the tubes, the molds are just warm, AND they are the same temp as the resin. Just curious, I know everyone has their own way of doing things.
 
Another note on the ultra sonic cleaner. I did some clear casting a couple weeks ago and noticed something interesting.

The ultrasonics continuously makes bubbles. I ran it for over 1/2 hour and bubbles never stopped forming. When the vibration stops, the bubbles would rise to the top. It took several minutes for the bubbles to clear after the untrasonics stopped, but then it looked good.

After seeing this, I plan to let colored resin sit for several minutes in the heat after the untrasonics stop, then remove, catalyze, cast.

It was interesting seeing what happens to the clear resin. I suggest trying a small clear cast for learning if nothing else - so you can see exactly what happens
 
OK,
Now it is geting more clearly for me. So I bought the one with heat.

Why heathing the molds?
 
seamus7227 said:
PenMan1 said:
If you heat the mold in a toaster oven, the bottom of the mold gets hotter than the sides which caused me big problems.
Click to expand...


Two questions regarding what happened to your test :

1) what was your temperature set at when you tried this

2) Does your toaster oven have a setting for 150 degrees?

The reason i ask if because i use my toaster oven at 150 maybe 148(even though there isnt a mark for that temp{148}) and I dont have any problems with my snakeskins burning or shriveling on the tubes, the molds are just warm, AND they are the same temp as the resin. Just curious, I know everyone has their own way of doing things.
Click to expand...

I have a very, very accurate stainless steel wireless temp probe that I use for many things. I know that 148 is my ideal temp because the little adjusting dial on my $15 toaster over varies between 98 degrees and 173 degrees with almost no movement of the dial.

I used the probe to get the oven as close to 150 as possible and scratch a mark where the dial should stay, and taped the dial to that location.

On the tray where the bottom of the mold sits the temp is 148, at the top of the mold (after 10 minutes of mold pre-heating) the temp is 111.

The problem this presents with multi-level pours is that the first pour or the bottom 1/4 of the mold starts to gel before the other colors can be added and swirled.

My simple solution was to quit pre-heating the mold for solid blanks and heat all "levels" of pr to 130 degrees.

On clear or embedded casts, I still pre-heat the mold as these set much slower anyway.

This is just MY WAY, not the right way.
 
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PenMan1 said:
seamus7227 said:
PenMan1 said:
If you heat the mold in a toaster oven, the bottom of the mold gets hotter than the sides which caused me big problems.
Click to expand...


Two questions regarding what happened to your test :

1) what was your temperature set at when you tried this

2) Does your toaster oven have a setting for 150 degrees?

The reason i ask if because i use my toaster oven at 150 maybe 148(even though there isnt a mark for that temp{148}) and I dont have any problems with my snakeskins burning or shriveling on the tubes, the molds are just warm, AND they are the same temp as the resin. Just curious, I know everyone has their own way of doing things.
Click to expand...

I have a very, very accurate stainless steel wireless temp probe that I use for many things. I know that 148 is my ideal temp because the little adjusting dial on my $15 toaster over varies between 98 degrees and 173 degrees with almost no movement of the dial.

I used the probe to get the oven as close to 150 as possible and scratch a mark where the dial should stay, and taped the dial to that location.

On the tray where the bottom of the mold sits the temp is 148, at the top of the mold (after 10 minutes of mold pre-heating) the temp is 111.

The problem this presents with multi-level pours is that the first pour or the bottom 1/4 of the mold starts to gel before the other colors can be added and swirled.

My simple solution was to quit pre-heating the mold for solid blanks and heat all "levels" of pr to 130 degrees.

On clear or embedded casts, I still pre-heat the mold as these set much slower anyway.

This is just MY WAY, not the right way.
Click to expand...


Ah! I didnt realize you were talking about solid color casting! My fault, but very interesting none the less. thanks for sharing! I take it for granted about the temp switch being different on toaster oven. I paid like 20 bucks for mine at Wally world. but it has the 150 degree mark indicated, it only took me a month to figure it out though, had the switch in the wrong direction, kept frying everything I was casting. The temp ended up being in the 350 position. Argh!! Sometimes i wonder about myself:rolleyes::frown:
 
le_skieur said:
OK,
Now it is geting more clearly for me. So I bought the one with heat.

Why heathing the molds?
Click to expand...

Preheating the molds aids curing of the resin. Heat causes the resin to harden. Pouring heated resin into a heated mold casuses the resin to cure faster. If you pour heated resin into a cold mold, it takes more time because the resin gives up heat to the mold to equalize temperature.

Hope that made sense and helps.....
 
Canadian_Kid said:
So would it be best to match the mold temp to the resin temp as close as possible?
Click to expand...

I usually preheat my molds to around 150F and my resin is usually 105F or so. This has a tendency to cause the resin next to the mold to heat up quicker and you get the resin to turn and mix on it's own. Just like heated water in a pan. The hot resin rises and the colder resin falls. Makes its own swirls.....
 
arw01 said:
Would you mind expanding a bit more?

Are you just preparing the resin in the ultra-sonic "cleaner" and not putting the mold into the water bath or something completely different?

Assuming the mold just is surrounded by the water bath, do they need to be weighed down, or does silicon sink naturally?
Click to expand...

I don't heat my molds, so I won't comment there.

I heat/agitate my resin in the mixing cups in the ultrasonic cleaner bath,
to help work out bubbles and (more importantly) to help break up any lumps of pigment.

The resin goes in thickness from basically water -> thin syrup -> thick syrup/ honey -> ketchup -> mayonaise.

When you're doing a swirl, the point you want to pour depends on how fine of swirls you want vs how distinct you want the colors. Finer swirls - pour while it's thinner. More distinct colors - wait until it is thicker.

For maximum color definition, you want to aim for the "honey" stage. The ketchup stage is still usable, but you're pressing your luck. You can make a blank using mayonaise stage resin, but you'll almost certainly have air bubbles in your blank as you basically fold the thinner resin into the thicker one, trapping air with it.

The reason to use heat is to make things happen faster so you don't have to wait around as long.

The reason NOT to use heat is to make things happen slower so you have a better chance of catching the resin at the right stage.


One other thing to consider when pouring is the relative densities of the colors. Ideally, pour the denser pigment last so it swirls through the lighter one. Otherwise the lighter one will tend to float on top and not swirl.
 
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Sorry guy's if I took so long too thanks you about all those precious informations. I was no able to connect in my vacation.

Thanks you again!!!!!
 
if you only want to heat enough resin for a few pens in the ultrasonic cleaner how are you keeping the cup from floating?

do you put some weight across the top or something?

blessings
craig
 
Yep...I place a chunk of wood across the top of the cup. The one I use is ...well, it doesn't matter. Just place a weight of some sort on top and be sure it is balanced on top or you will be cleaning polyresin from the inside of your cleaner....what a mess...or so Seamus told me.:biggrin::biggrin:
Do a good turn daily!
Don

clapiana said:
if you only want to heat enough resin for a few pens in the ultrasonic cleaner how are you keeping the cup from floating?

do you put some weight across the top or something?

blessings
craig
Click to expand...
 
its_virgil said:
Yep...I place a chunk of wood across the top of the cup. The one I use is ...well, it doesn't matter. Just place a weight of some sort on top and be sure it is balanced on top or you will be cleaning polyresin from the inside of your cleaner....what a mess...or so Seamus told me.:biggrin::biggrin:
Do a good turn daily!
Don

clapiana said:
if you only want to heat enough resin for a few pens in the ultrasonic cleaner how are you keeping the cup from floating?

do you put some weight across the top or something?

blessings
craig
Click to expand...
Click to expand...


ROTFLMAO! In the words of Ole' Roy, "Been there, Done that, Got the T-Shirt.

MAKE SURE TO USE GLASS OR RECYCLE CODE 5 CUPS WITH THE USC, or you'll be cleaning goo out of the cleaner for days! DAMHIKT:biggrin:
 
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