Polyester Resin

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Bobostro61

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Jan 5, 2013
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OK, I decided to try my hand at blank making. I bought some of this stuff at Hobby Lobby:
IMG_1048.jpg

How much of the catalyst do I need for two ounces? The chart on the container doesn't make much sense to me as the thicker the layer the less catalyst you use. Seems like it should be the other way around.

I used 8 drops of catalyst per ounce (so 16 drops). It seems like its taking for ever to get to that "gel" state.
 
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RMayoIII

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Feb 14, 2012
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I started with that resin and have since changed to silmar 41. If I remember correctly I used 10-12 drops per ounce and it still takes a while before it gels. But once it starts to gel you have very little time before you have to leave it alone. Maybe with less activator you will have more time to play in the gel state. Temp and humidity play a role in resin casting also but there ar plenty of threads to read up on that!
 

Bobostro61

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As I was typing my question, it decided to gel up on me. Right after I added some color to swirl in. Another screwed up blank. Oh well, it's only my second attempt. Live and learn as they say. Thanks for the info.
 

Pjohnson

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Feb 16, 2012
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Plympton, MA
I use 6-7 drops of MEK per ounce. Some colors set faster than others. To track and learn I keep a blank recipe book that includes amount of color and MEK.

I refer to it each time I cast.
 

longbeard

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I use the same stuff, i put 7 drops an ounce and within 3 to 5 minutes, i need to have it in the mold and going into the pressure pot. Thats using 2 different colors.

Are you mixing your colors into your resin before you add mekp? you should if not.
 
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Bobostro61

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I use the same stuff, i put 7 drops an ounce and within 3 to 5 minutes, i need to have it in the mold and going into the pressure pot. Thats using 2 different colors.

Are you mixing your colors into your resin before you add mekp? you should if not.

That's kind of what I'm trying to figure out. What I want, and tried to do this morning unsuccessfully, is make a blue blank with the pearl sparkly stuff in it and add a yellow swirl. No luck...

I mixed in the blue and pearl and added the catalyst. Messed it up when I went to add the yellow. Is it better to just make solid colors with this polyester resin and forget about having different colors in the blank?
 
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You need to mix your colors thoroughly in your cup right away then add your mekp. I us Silmar 41 but for a 9oz cup I use 20 drops. Th less drops the longer it will take but when it does start getting thick, it gels much slower and you have more time.
You need to stir and check often (dont stir violently)

You need to have everything ready to go so when it is time to pour you are not scrambling.
The ideal consistency is like Thick syrup. When pouring, alternate the colors in the mold then flip the colors with a thin stick of some sort after pouring.

If you can get a small oven, you can put it on 275ish and stop the colors from bleeding into each other so much.

Some colors will thicken faster then others.
 

NewLondon88

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Claremont NH
How much of the catalyst do I need for two ounces? The chart on the container doesn't make much sense to me as the thicker the layer the less catalyst you use. Seems like it should be the other way around.

I used 8 drops of catalyst per ounce (so 16 drops). It seems like its taking for ever to get to that "gel" state.

The chart is right. The thicker your pour, the more heat it will hold.
Generate too much heat and you will get a brittle blank, or perhaps it
will crack on you before you turn it.

I generally run about 3-5 drop per ounce.. maybe a little more if the
catalyst is getting old.

I try to avoid getting resin at the craft stores if possible. Their staff
aren't generally familiar with casting, so they don't really understand how
critical "stock rotation" is. They'll put the new stuff in front of the old,
and it could sit there for quite some time. Old catalyst seems to take
longer to kick and makes your results a bit less predictable.
I know Cast'n Craft does have a date code on the bottom of the can,
but I don't think the catalyst does.
 

longbeard

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I use the same stuff, i put 7 drops an ounce and within 3 to 5 minutes, i need to have it in the mold and going into the pressure pot. Thats using 2 different colors.

Are you mixing your colors into your resin before you add mekp? you should if not.

That's kind of what I'm trying to figure out. What I want, and tried to do this morning unsuccessfully, is make a blue blank with the pearl sparkly stuff in it and add a yellow swirl. No luck...

I mixed in the blue and pearl and added the catalyst. Messed it up when I went to add the yellow. Is it better to just make solid colors with this polyester resin and forget about having different colors in the blank?

Are you trying to add 2 colors in the same cup before you pour in the mold? Maybe not, thats how i read it. Anyhow, if your using 2 or 3 colors, you need 2 or 3 cups with the amount of resin that will fill your mold, if your mold will hold 3ozs. of resin, divide the resin up in each cup. For example: Most of the time i use 2 colors. I decide which color i want as the main color. My 3/4'' mold will hold 2 3/4 oz. of resin. I might pour about 2oz. of resin in one cup, 3/4oz of resin in another cup. Mix my colors in each cup then add the mekp to each cup. When the time is right, i will pour the colors into my mold, a cup in each hand, swirling just a bit as i pour, then i will use a toothpick to swirl a little, then to the pot for pressure.

Hope this helps, YMMV depending on temp, humidty and such.
Trial and error is the biggest thing, keep track of everything you do.
 

BSea

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Casting is sort of like learning to drive a stick shift. You mess up a lot in the beginning, but once you get the feel, it almost becomes 2nd nature. I was told that it takes about a gallon of pr to start to get competent with pouring blanks. That was pretty much true for me. I use silmar 41. I've never used the casting craft PR. I have used their catalyst in a pinch. I use 4 drops per ounce except with a few colors that I use 3 because they gel so fast.
 

Bobostro61

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Chicago, IL
Casting is sort of like learning to drive a stick shift. You mess up a lot in the beginning, but once you get the feel, it almost becomes 2nd nature. I was told that it takes about a gallon of pr to start to get competent with pouring blanks. That was pretty much true for me. I use silmar 41. I've never used the casting craft PR. I have used their catalyst in a pinch. I use 4 drops per ounce except with a few colors that I use 3 because they gel so fast.

Where can I get that Silmar 41 and some catalyst for it to boot? Is it cheaper than the Castin' Craft? That was $25 for 16 oz.
 

BSea

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I buy mine from either US Composits, or IllStreet. Because the amount of mekp we use is so small, when I order from Illstreet, I ask for no mekp. And the reason I don't is for 2 reasons. 1 I don't want any more extra mekp around that necessary, and I've gotten a bad batch from Illstreet, so when ever I need mekp, I order from US Composits. The resin is a bit cheaper from illstreet, but they are just a volume customer of US Composits that repackages the same resin.
 

Ed McDonnell

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Oct 20, 2008
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Melbourne, FL
I buy mine from either US Composits, or IllStreet. Because the amount of mekp we use is so small, when I order from Illstreet, I ask for no mekp. And the reason I don't is for 2 reasons. 1 I don't want any more extra mekp around that necessary, and I've gotten a bad batch from Illstreet, so when ever I need mekp, I order from US Composits. The resin is a bit cheaper from illstreet, but they are just a volume customer of US Composits that repackages the same resin.

Hi Bob - Are you sure about that? Silmar is a product of Interplastic Corp. Interplastic has a distributor network, but neither Illstreet nor US Composites are distributors. I always thought they both just bought in bulk from one of Interplastic's distributors and repackaged.

Ed
 

BSea

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Little Rock, Arkansas
I buy mine from either US Composits, or IllStreet. Because the amount of mekp we use is so small, when I order from Illstreet, I ask for no mekp. And the reason I don't is for 2 reasons. 1 I don't want any more extra mekp around that necessary, and I've gotten a bad batch from Illstreet, so when ever I need mekp, I order from US Composits. The resin is a bit cheaper from illstreet, but they are just a volume customer of US Composits that repackages the same resin.

Hi Bob - Are you sure about that? Silmar is a product of Interplastic Corp. Interplastic has a distributor network, but neither Illstreet nor US Composites are distributors. I always thought they both just bought in bulk from one of Interplastic's distributors and repackaged.

Ed
Well, now that you mention it, it was what I heardfrom another member. So I`m not positive. But I do know of 2 cases where the mekp was bad. But I`ve also heard that others have used it with no problems.
 

carpblaster

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Dec 12, 2011
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Shelby,Alabama
Had no problem with dixie cups, 3-4 at a time, got the color in ,3-5 drops per oz,done nothing till it started to thicken up,then either 2 cups in each hand or 2 and 1,Got a cheap lazy susan at the thrift store, I put tape around the top of my mold,it had 6 holes,i started the lazy susan turning or some one to help and started pouring, all kind of colors comeout, if you got the mix right ,it doesn matter if your hitting the hole,i have enough for the holes i needed and just let it run wherever,and sometimes just scraped it in with a pop stick,I use masking tape on the top edge of form so it would not run down it, had some great blanks come out,if you dont want to use all the holes i filled them up with rags or towels,when i was pouring for the slimlines in 1/2" pvc, i would put 4 together tape them make a base out of 2"pvc and set them in it, fill up the gaps between the pipes and measure and pour 4 at once with the tape on top,saves from making a mess, and you will make a mess learning,good luck
 
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