My first Cholla

[Monty]

This is the first cholla I have attempted. I cast two separate blanks and this was the first on I turned. This one appears top have a milky area that is in some areas. The resin is Castin Craft. Any ideas as to what caused the cloudiness? It doesn't look like it's in the second blank, but than I haven't turned it yet. If it was alumilite, I'd say it was moisture, but the cholla was very dry.

 

[PTownSubbie]

Mannie,

It almost looks to me like a pigment problem. Either not mixed very well or a very very thin area on top of the cholla. I have seen with some Worthless Wood castings where the color is different in some very thin areas of the PR.

What did you use for pigmentation?

Just a thought though.

 

[Craftdiggity]

Mannie, I had the same initial thought as Fred. It appears to me that the pigment is not mixed all the way through. I had the same thing occur the first time I tried casting burls with resin. I guess I got impatient and did not do a good job mixing my colors all the way. The result was some cloudy areas and some areas that were even fairly clear.

 

[Monty]

No pigment was used. The Cholla was cast in clear resin. The tubes and inside the blank was painted with Testors black model paint and allowed to dry overnight before gluing the tubes in.

 

[PTownSubbie]

Got me then....

Could it be lack of adhesion inside the opening? PR shrinks as it cures. But that doesn't explain the surface cloudiness on the surface of the blank.

Cast with Pressure? If so, you would think the above would be non-applicable....

 

[Monty]

It's not noticeable in the picture, but I can see the same cloudiness next to the cholla in several areas. Like Fred says, almost looks like bad adhesion. I'll also point out I cast under 60psi overnight. The pressure fell slightly to 50psi during that time.

 

[ldb2000]

My bet would be on moisture . Since it appears to be localized I would guess a drop of sweat or a damp fingerprint got on the cholla and since it was very dry wood it soaked in deep then leached out from the curing heat of the resin .

 

[Skye]

The cloudy area around the top of the blank, left side, the black portion, looks like the cloud is in between the black and the brown all the way around the black streak. Is it possible it's pulling fumes from the CA off the barrel, through the wood, into the resin?

 

[PTownSubbie]

But PR doesn't react with CA. If it did, we wouldn't be able to use CA finishes on our castings...

Butch, same thing. I know PR doesn't like moisture but I thought moisture prohibited curing. I didn't think moisture would cause cloudiness... Have you seen that before?

 

[PTownSubbie]

Mannie,

You didn't mention when you found the cloudiness. I assume it wasn't there when you constructed the pen?

Was the part extremely tight pressing it into the pen? I had a spot that debonded (if that is the right word) when pressing in the top of a Jr. Gent II on a Worthless Wood blank. The extra pressure caused some separation of the casting from the wood and created a discolored area. Wonder if that is what happened and you didn't notice it right away.

 

[Monty]

Mannie,

You didn't mention when you found the cloudiness. I assume it wasn't there when you constructed the pen?

Was the part extremely tight pressing it into the pen? I had a spot that debonded (if that is the right word) when pressing in the top of a Jr. Gent II on a Worthless Wood blank. The extra pressure caused some separation of the casting from the wood and created a discolored area. Wonder if that is what happened and you didn't notice it right away.

I could see what I thought was some cloudiness right after I removed it from the PVC mold, but before I even drilled it for the tube.
I have another blank that was cast at the same time but not yet cut or drilled. It doesn't appear to have this. I'll have to double check it tonight and inspect it closer.