RCBS pot and alu molds?

[jayjay1]

Hey guys,
at my last casting, I´ve noticed, that the used alluminium mold started to stick a little bit, by gliding over the mold rod of the pot.

I´m wondering why this happens.
Well, the paint on the rod begins to drop a little and there are some scratches on the bottom of the mold, but sticking like this?
It felt as if the mold was glued a little bit on the rod, so that I had to push it to get the holes at the right place (what then often failed).

What the heck is that and how can I correct this?


Cheers,
Jay

[dromia]

Hove you cleaned and polished the bottom of the mould and the guide rod?

Have the guide collars on the rod moved? Are they clean?

The guide rod hasn't twisted a bit so that the mould it now tight on the collars when aligned?

Not much to go wrong there so should be simple enough to find the problem.

[jayjay1]

Yes, everything was in the right place, no twisting and some space between mold and collars.

I will now clean and polish the rod, what I did with the mold yesterday after the cooldown of course.

The mold really was somehow like stucking.
I thought it might be to hot and the mold melted a little bit to the rod, but the temperature was good to go.
The mold itself was a little bit difficult to open at the end, I gave one of the grips a little hit and it worked.

I have no idea, but will no check the pot.

[Jon K]

Spray the bottom of the mould with mould release. I usually spray the bottom an ends, to keep spatter from sticking to mould also.

Jon

[jayjay1]

Ok, I´ve checked the rod and found some little burrs on it, which seemed to be there under the paint (which is mostly gone now).

I´ve treated it with some sand paper 400 and polished it and did the same with the bottom of the mold to reduce the scratches.

In cold condition the mold ran now smoothly over the rod - looks good!
[smilie=s:


P.S.:
This was my second casting session with my first aluminium mold and I ran it a little hotter like in the first session.
So I was a little bit insecure about this problem.

[dikman]

Don't worry about the mold, you shouldn't be getting things hot enough to melt anything except lead! If the mold is sticking together, try cleaning it with alcohol or a solvent of some sort - you want everything clean.

[jayjay1]

What kind of solvent do you mean?

Like barrel/gun solvent?

[dromia]

Acetone, Isoprophyl alcohol, hot water and washing up liquid, methylated spirits and such like take you pick. Boiling the mould for ten minutes or so with a drop of washing up liquid is good but can discolour aluminium moulds, cosmetic change only.

Don't use an oily solvent.

[jayjay1]

Thanks dromia, very kind to help a newbie with this.
:drinks: