determining weather sheet is cast or extruded

[rtbm]

Is there any simple way to tell if a sheet of acrylic is cast or extruded? Like any obvious differences in appearance or anything like that? For example.

[Adam]

rtbm,

True extruded sheet will have extrusion lines in it, but this type of sheet is rare.

"Continuous cast" sheet uses a process in between extrusion and cast (I don't know the details) and is very hard to tell.

If the masking is still on, you can look up the product code on the 'net.

Adam

[rtbm]

Unfortunatly the masking was removed long ago. In fact the sheet in question has already been welded as a bottom for a 125 that had cracked. The tank was given to me. The peice used is 5/16 and the guy who repaired it did not know if the acrylic he used was cast or extruded. Perhaps a better question would be, would it be ok to use the tank if the bottom was extruded acrylic?

[Avast Marine]

If you are unsure it wouldn't be that hard to laminate a sheet of 1/4" cast over the acrylic in question. I would do this regardless if you at all doubt the strength of the "repair".

[rtbm]

Actually that would be a little tricky as the sheet is now the bottom of this 125, and there is a top as well. It could not be done in one piece. Is there a real danger to using it if the bottom isn't cast? Like I said before it is 5/16 thick. The only other option would be to cut the bottom off and replace it with what I knew to be cast. That's really why It would be nice if there was a way to determine if it was extruded or cast.

[Reefbox]

Most likely if the guy doing the repair did not specificaly want cellcast he probably bought what the store (Lowe's or Home Depot) had and that is extruded. Hopefully not in your case.

I would think about getting a new tank down the road, for peace of mind, especially if it is filled with thousands of dollars of living reef.