Rubber stopper woes

[TomW]

I'm using rubber stoppers from the tattoo industry and casting in Alumilite. I'm having a problem with the stoppers sticking after cutting the blanks separate. Is a release agent of some type necessary to make this easier? The last ones I had to resort to pen mill to get them out.

Also am getting a little trace of blue rubber past the edge of my tubes, causing me to have to use pen mill to shorten the tubes ever so slightly to remove the trace of blue.

As always, your suggestions are appreciated.

Tom

 

[NewLondon88]

Do you have any pics to give us a better idea?

 

[TomW]

No pictures because I just cleaned up the last ones.

But close your eyes and imagine: You are making a snake skin casting. The casting works great. You cut the Alumilite block into separate blanks. You cut the ends off of the stoppers. You play "heck" getting the rest of stopper out, resulting in having to use pen mill.

Problem two...keep your eyes closed. Now that the stopper is out, there is a small "rim" of blue at each end of the snake skin. Pen mill the alumilite down to the end of the tube... still blue rim. Mill the tubes shorter to get rid of the blue.

Now open your eyes..... See?

It's like pressure is forcing the stoppers into the tubes and the stopper is bulging around the end of the tube and between the tube and snakeskin. BTW this is not snake skin, it's my new invention that is gonna make me rich (if you guys will solve my stopper problem... )

Tom

 

[JohnU]

Tom, thats what I use but I dont use a lot of alumilite, mostly PR. Usually after the second cast mine start to stick. I usually cut them and let them sit for a day or two and they often start to work themselves out. I use very long thin needle nose pliers, open them a bit, stick them in the middle of the rubber cork, squeeze them and pop the corks out. Sometimes I have to push in on on the cork around the edges to unstick them. The only time Ive had blue rubber get on the cast is when I had to cut the corks down in size. Now I try to get corks to fit inside so I dont have any edges sticking out around the tubes. Not sure if this helps you or not. Good Luck, John

 

[TomW]

John,

These are single use stoppers. I am casting in a block and cutting the ends off to expose the remainder of the cork. I have not tried letting it set for awhile.

Thanks
Tom

 

[JohnU]

Tom, This is how I use them. I push the blue corks in the tubes and glue to left over resin scraps and wedge in the molds so they dont move around. Take out the block, cut them apart and then cut at the top egde of the blue corks. Then push in on the sides of the corks to loosen them from the pr and stick the pliers in. Then I squeeze the pliers, pull but not straight out, kind of like a bending motion. Then I cut off the extra resin, mill the ends down, and reuse the corks. I often get three or four pours on on cork before its too short to use. Sometimes they tear but thats why I buy 500 to 1000 at a time. Hope this helps. John

 

[TomW]

John,

Everything is the same for me except the pliers tear up the stopper due to it being stuck. I have to cut the alumilite very close to the tube (making a very short sopper) to have any chance of getting it out in one piece. Plus the blue rim around the outside of the tube.

Tom

 

[NewLondon88]

But close your eyes and imagine: You are making a snake skin casting. The casting works great. You cut the Alumilite block into separate blanks. You cut the ends off of the stoppers. You play "heck" getting the rest of stopper out, resulting in having to use pen mill.

You had me up until cutting off the stoppers. I guess you're not using
your ResinSaver (tm) molds. ahem. :tongue: How high are you pressurizing?
You don't need much .. too much pressure will cause problems with
stoppers getting pushed into tubes, resin shifting, air pockets forming
and other things..

Problem two...keep your eyes closed. Now that the stopper is out, there is a small "rim" of blue at each end of the snake skin. Pen mill the alumilite down to the end of the tube... still blue rim. Mill the tubes shorter to get rid of the blue.

Now open your eyes..... See?

It's like pressure is forcing the stoppers into the tubes and the stopper is bulging around the end of the tube and between the tube and snakeskin.

ok, that's pretty much what I'm picturing. But if there's enough pressure
to deform the stoppers, that's too high. You need enough to keep any
gases in suspension, and that's also enough to keep the stoppers against
the rim of the tube and keep the resin out. But more than that .. you'll
start warping the stoppers and forcing them into any nook and cranny
they can find. Because the resin can't compress, the rubber will. And
that means that your resin can shift. (famous silvery bubbles?) And you
can shove the rubber into the spaces in between the tubes, the resin
and the skins.. De-lamination is almost guaranteed, I'd think..

BTW this is not snake skin, it's my new invention that is gonna make me rich (if you guys will solve my stopper problem... )Tom

We can talk about consulting fees over martinis
I'll have my people call your people. We'll do lunch.

 

[TomW]

60 psi is what I've been using. It does seem like the stoppers are getting pressed farther into the tubes.

As for the drinks, I think George has some wine left over. He can provide the entertainment too (Counselor jokes).

Tom

 

[JohnU]

Im guessing its the alumilite. I had some lables cast in it from a month ago and just went to pull the corks out. I they all broke on me, but I didnt have any trace blue. Now I remember why I stay with silmar. lol good luck, John

 

[NewLondon88]

60 psi is what I've been using. It does seem like the stoppers are getting pressed farther into the tubes.

Just for grins, try one at 20-25psi. That's enough to hold the tubes in place,
keep out the resin and keep gas in suspension. I don't think you gain
anything at higher pressure than that.

 

[Dai Sensei]

As NewLondon88 suggests, try lowering your pressure. I've been using 2bar=28psi

 

[RAdams]

A little birdie told me that anything over 25 or 30 psi is a waste anyway. That being said, i would also try it with less pressure.