Repairing Holes.

**Dennis** · 13-05-2014, 08:08 PM

Lucy, I don't really see how voids in your wax, provided they are below the surface, can be translated in your castings. If castings come back with bubbles it is the fault of your caster. They can avoid them by using a vibrator when investing, or by using a vacuum pump.

If they are blaming you, go elsewhere. Dennis.

**ps_bond** · 13-05-2014, 08:40 PM

I'd agree - if the surface of the wax is clean, then the investment should conform to that. The wax could look like an Aero internally and it wouldn't make a difference.

I did mean I can help fix porosity in the cast rather than in the wax I'm afraid! And not with solder.

**Lucie** · 13-05-2014, 09:23 PM

The surface of my waxes are completely perfect - quite literally filled and polished. I'm now on my 4th caster & have had the problem for years now. Approximately 50% of all castings have hairline cracks. I get around it by making duplicates but its a huge waste of time. I was told today that during casting the vacuum can draw bubbles to the surface. Is this complete nonsense then?

**Dennis** · 13-05-2014, 10:01 PM

Well Lucy, they are not bubbles from your wax, because that burns out completely, leaving an empty mould. If bubbles occur it is due to gases in the molten metal, so causing holes or porosity.

Actually my post above is nonsense too, because holes in the investment would cause small beads on the casting. However, you would be wise to go on searching for a better caster. I have used West One Castings in Hatton Garden, and so have other members, so you might try there. http://www.londononline.co.uk/profiles/181879/ Dennis.