casting issues!!!

[ldubia]

I have tried my hand casting three times. The first time I was successful and made four pens from the cast. The second time I tried putting shavings of different woods in the material and it would not cure over the course of three weeks! The third casting I added chunks of wood to give it a little something (I'm experimenting) for color. I used casting crafts acrylic. I measured out the amount needed, added the catalyst, then added the wood after thoroughly mixing it. I let it sit in a shielded place to keep dust and debris away from it while I turned. The weather has been warm but not hot or humid. Cool at night but it has been indoors.

It has been three days now and it is still not 100% cured. The bottom was yellowed and still viscous. The sides were mostly cured, top the same.

What am I doing wrong here? Any help at all would be appreciated. I would like to learn how to cast successfully to try some of the things I am thinking of.

Larry

 

[pensbydesign]

i have had a few castings that didn't what to cure, i baked them off in a toaster oven at low heat for about 20 min. did the trick.

 

[Skye]

Well how old is the jug and how many drops of catalyst are you using per oz of resin?

 

[PTownSubbie]

It could be several things.

1. Uneven mixing of the catalyst in the PR. It seems like a really long time but I mix for 2min as measured by the clock.

2. Whenever you put things into the resin, the amount of catalyst required to complete the cure goes up. Resin cures through heat. The catalyst causes nothing more than a chemical reaction to create heat. If the resin is spread out and not bunched together because of the pieces added, the heat generated drops tremendously and the cure doesn't happen like normal. (hope that makes sense).

These are my initial thoughts.....

 

[PR_Princess]

What was the wood Larry? Was it a naturally oily one?

PR does not always play nice with oily woods. Your yellow and viscous problem sounds like one that I have had in the past with cocobolo and PR.

 

[workinforwood]

In my opinion and experience...

PR...for making a total plastic pen blank
For casting tubes with labels or skins on them
For casting blanks that have chunks of hard plastics, IE busted up PR or corian chunks

Alumilite...for making a total plastic pen blank
For casting a pen blank with random objects in it like chunks of wood, cereal, pasta, pine cones etc.
For casting a blank with soft chunks of plastic in it, ie..bowling balls, busted up alumilite pieces, ebonite chunks, etc

 

[ldubia]

i have had a few castings that didn't what to cure, i baked them off in a toaster oven at low heat for about 20 min. did the trick.

Thanks. I will have to get a used one from the junk store and try that. I need one anyway to try my hand at making the small molds and curing them as well as drying the blanks.

Well how old is the jug and how many drops of catalyst are you using per oz of resin?

The resin is a few months old. I calculated 4 oz of resin and it said to use 6 drops per oz. I then added three extra drops to account for the space taken by the material being added to induce more heat to replace what was taken by the added wood.

It could be several things.

1. Uneven mixing of the catalyst in the PR. It seems like a really long time but I mix for 2min as measured by the clock.

2. Whenever you put things into the resin, the amount of catalyst required to complete the cure goes up. Resin cures through heat. The catalyst causes nothing more than a chemical reaction to create heat. If the resin is spread out and not bunched together because of the pieces added, the heat generated drops tremendously and the cure doesn't happen like normal. (hope that makes sense).

I mixed the resin for about 1.5 minutes using a small stir stick making sure to get all the material at the edges. I even tilted it and scraped the material around the bottom to get it well mixed.

I did add three extra drops to the mix to account for the added wood.

What was the wood Larry? Was it a naturally oily one?

PR does not always play nice with oily woods. Your yellow and viscous problem sounds like one that I have had in the past with cocobolo and PR.

The woods used were small bits of padouk, maple, cocobolo laminated together. Also redwood, purple heart, some acrylic leftovers, box elder burl that has been stabilized, and a chunk of cocobolo. I hadn't thought about the oil in the cocobolo. DOH!

In my opinion and experience...

PR...for making a total plastic pen blank
For casting tubes with labels or skins on them
For casting blanks that have chunks of hard plastics, IE busted up PR or corian chunks

Alumilite...for making a total plastic pen blank
For casting a pen blank with random objects in it like chunks of wood, cereal, pasta, pine cones etc.
For casting a blank with soft chunks of plastic in it, ie..bowling balls, busted up alumilite pieces, ebonite chunks, etc

I think I am going to invest in some Alumilite for casting. I plan on more of this stuff that I tried today. I have some ideas I am dying to try out but have to get the casting to work first.

I also want to learn the art of WW casting. I lots of wood I have been saving for that particular reason.

Larry

 

[Brooks803]

another thing to keep in mind is whatever it is that you used for color as well as the amount used.

 

[ldubia]

another thing to keep in mind is whatever it is that you used for color as well as the amount used.

I left the resin clear and planned to use a black tube for depth. I thought it would show the wood better.
Larry

 

[ldb2000]

Not sure where you bought your Castin craft resin , the Michaels by me has had the same cans on the shelf for over 6 months now and who knows how long it sat in a warehouse before that . The MEKP has a shelf life of less then a year and only 6 months according to some here . The resin and MEKP could just be old and have gone bad . Try a cast of just resin to see if it is still good or if it was reacting with the oils in the wood .
In the future buy your resin from a good source . US Composites always has fresh supply of resin and hardner .

 

[ldubia]

Not sure where you bought your Castin craft resin , the Michaels by me has had the same cans on the shelf for over 6 months now and who knows how long it sat in a warehouse before that . The MEKP has a shelf life of less then a year and only 6 months according to some here . The resin and MEKP could just be old and have gone bad . Try a cast of just resin to see if it is still good or if it was reacting with the oils in the wood .
In the future buy your resin from a good source . US Composites always has fresh supply of resin and hardner .

Sounds like a good idea. I bought this through an art store. No telling how long they have had it. Oh well.
Larry