[Problems with air-release mold]

1 hour ago, Bill Kielb said:

Yes, It appears much of your release air is along the perimeter which reduces the air pressure in the middle so no lifting force in the middle. You could just seal the perimeter of this mold to try and confirm. The air under the slab will migrate to the perimeter on its own anyway. Score the edgeline all around before applying air.

Bill, what do you mean by "score the edgeline"? Do you mean seal the plaster on the edges? Please elaborate. Thank you!

 

Michael

[Problems with air-release mold]

2 hours ago, Jeff Longtin said:

You have good air flow/purging so that's good. The design looks FAIRLY unobtrusive, so that's good. 

Thinking about it...the folks who use the presses, at the pottery shop, do allow their clay to stiffen. They are, however. using 30 ton presses. Can you use stiffer clay and pound it in using a hammer? (There's a video online showing such a process.) 

The RAM press also allows the user to throw the mold into vacuum. Does your device allow that? A drier surface could also help.

Pure-Lube is described as a separating compound. (Like Murphy's Oil Soap.) It's typically used to separate plaster from plaster in the mold making process. If its working for Mark, great, but I would not recommend in this situation. 

Thanks Jeff. I do hammer it in lightly with a mallet. How much would it put me back for a little RAM press set up (or any hydraulic set up) that could make tiles up to 5 or 6 inches? 

--Mike

[Problems with air-release mold]

2 hours ago, Bill Kielb said:

Hard to tell in the video but it looks like a bunch of release air along the perimeter and maybe little to none in the decorative relief lines. My thought -  I think it would be preferential to release center out to overcome the roughly 14.7 PSI on the effectively evacuated interface plus any adhesive forces if you will, or at least uniformly from center out before the pressure escapes along the perimeter. For the local adhesion issue, a suitable mold release seems likely a decent easy fix.

Thanks Bill. I am not sure I understand what you mean. Are you saying that I will probably need to make another air-release mold and to densly pack the air tubing in the middle area? I tried a non-stick spray out of desperation and it seems to release much better. But it also left the top a little greasy. And I am not sure what this would do to the pores of the plaster over time....

 

[Problems with air-release mold]

I went back and tried to sand away any under cuts

I don't think it is that as I put a small pug in the middle where there are no real hard edges and with the air pressure it still did not pop out.  I am thinking that it has something to do with the clay turning into a kind of mud and forming water adhesion, suction, that the small air bubble aren't overcoming. 

I tried to dry it off a bit and apply slightly drier clay (which is harder to push into the design). But it actually released better -- haltingly-- after about 8 seconds. But look at the clay film that it leaves behind on the ceramic mold. This suggests to me that something is wrong with adhesion to the ceramical for some reason. 

Any thoughts?

 

[Problems with air-release mold]

I just might use the mold release that Mark recommends. But I still will want to know what I have done wrong for the air release not to work properly. I don't see any drastic undercuts. The Ceramical should be fresh enough.  Just ordered it about a month ago from the ceramic shop.

And the little air bubbles seem to be working. But it just partly comes out and gets hung up in the mold. These things should be dropping after 5 seconds of pressure.  I have wondered if it was TOO wet and was forming a kind of slip with the clay I put in the mold, and thus clinging to the plaster surface....

see video. 

 

[Problems with air-release mold]

Mark: The Tiler has been discontinued. The manual and instructions only say to keep it moist. I've tried all kinds of variations of wet and moist. The tile just doesn't pop out as it should.  The brown clay seems to want to cling to the plaster too much. I tried wet sanding the plaster to give it less texture but that doesn't seem to have helped one bit. 

Can the mold lube be used with an air-release? Without clogging the capillaries?

thanks

Md

[Problems with air-release mold]

Hi, I poured my first air-release mold (to use with a Texas Tiler). The mold is very erratic in whether or not it releases the tile as it should. The tile just stays in there. I tried various things. I filed down and sanded angles to help remove any undercuts. That didn't work really. I sanded the surfaces with wet sandpaper to make it smoother. I even tried a little soap with little improvement. 

Any tips? 

Wetter or dryer clay? Non-stick spray? (will it clog the air pores?)

I use about 60 to 70 psi. The mold is made from ceramical. (spelling?). It bubbles a lot from the surface so I know air is making its way. 

Please. please. please, any advice from experience!

--- Michael