Casting or stabilizing help needed

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Rmartin

Rmartin

Member
Joined
Jan 14, 2007
Messages
1,263
Location
Columbus, Ga, USA.
So, I bought these beautiful blanks from board member Isaac Rapelje. My experience with casting has been limited to casting a few clear blanks using Craft store resin. I would like to fill the voids with colored resin.

How do you suggest I do it?

Does it need to be done under pressure?

I've read all the casting tutes in the Library, but they all seem to be geared toward solid blank casting.

Are there any worthless wood tutes I am missing?

jarrahcasting.jpg
 
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Not an expert but I would say yes those are a perfect candidate for PRESSURE casting. MIght be able to without but I'm guessing no as it needs forced into the voids.
 
I would say that due to the tightness of those voids you are going to need a pro cast them for you and you might not get all the voids inside the blank filled .
 
ldb2000 said:
I would say that due to the tightness of those voids you are going to need a pro cast them for you and you might not get all the voids inside the blank filled .
Click to expand...

Some of the cracks are tiny, but some go all the way through. Too unstable to try to turn them as they are. I thought I might fill the larger cracks and then do the rest as I turn them down. This may be too time consuming though. Or I could buy the pressure equipment I need to cast them properly. I'm ready and unafraid to take the next step.

I have more than sixty of these blanks and I hope to be a pro by the time I'm done with them.
 
PM one of the more experienced casters here and talk to them. If that doesn't appeal to you, there is certainly something said for doing it on your own but...........
You might save some money on resin by getting some tips from an experieced friend.
 
Curtis (mesquiteman) would be my "Phone a friend" choice for this project. He has lot of casting experience and experience working with void wood.

Each time that I have PM Curtis, his answer has always been prompt and the advice, spot on.
 
I know I'm going to be in the minority here, but I'd prefer to use vacuum.

If you submerge the blanks and pull a vacuum it will draw out the air.
When you release the vacuum the void space will be replaced by the liquid
as the blank reaches equilibrium. Open the pot, turn the blanks and repeat.
You don't need the vacuum for more than a few seconds at a time.

Now the issue is making sure the resin is thin enough to flow easily. You
can warm the resin to lower the viscosity or some resins will take a
thinner. (PR, for instance, can be thinned with styrene) Or both.

I've tried pressure, but unless you can hold the pressure right on the
money, it can cause the resin to move as it cures. Mine was never quite
that good.
 
Vacuum would be fine IF you are using PR. If, however, you are going to use Alumilite (highly recommended for Worthless Wood casting) then you will not have enough time to pull a vacuum and release. Using vacuum is basically just pressure casting with 14.7 psi (if you are at sea level on a standard atmospheric day!) I guarantee you I could cast those with virtually no voids unfilled. I say virtually because in order to fill all the voids, they have to have some sort of connection path to the surface in order for the resin to get in there to begin with. I have done lots of blanks like that with great success.
 
I thought that vacuum removed the air, whereas, pressure just compressed the air that is present.
 
MesquiteMan said:
Vacuum would be fine IF you are using PR. If, however, you are going to use Alumilite (highly recommended for Worthless Wood casting) then you will not have enough time to pull a vacuum and release. Using vacuum is basically just pressure casting with 14.7 psi (if you are at sea level on a standard atmospheric day!) I guarantee you I could cast those with virtually no voids unfilled. I say virtually because in order to fill all the voids, they have to have some sort of connection path to the surface in order for the resin to get in there to begin with. I have done lots of blanks like that with great success.
Click to expand...


14.69 psia is atmospheric pressure. When pulling a vacuum, it's anything less than that all the way to zero, which can't be attained. 14.7 psia = 0 in. Hg. and if you could pull a perfect vacuum to 0 psia, that would = 29.92 in Hg. which is a pressure increase. Correct?
 
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Uh oh, the vacuum/pressure debate could get ugly.

Thanks for the replies and thanks Curtis. Your worthless wood tutorial is excellent.

I have a friend who is a paint contractor for the military. I'm going to check with him tomorrow to see if he has an old pressure pot before I buy from Harbor Freight.

I bought some metal powders awhile back. Will all powders work with Alumilite? I also need to decide what colors will look best with these blanks. They have a dark reddish color with black near the voids.
 
DozerMite said:
MesquiteMan said:
Vacuum would be fine IF you are using PR. If, however, you are going to use Alumilite (highly recommended for Worthless Wood casting) then you will not have enough time to pull a vacuum and release. Using vacuum is basically just pressure casting with 14.7 psi (if you are at sea level on a standard atmospheric day!) I guarantee you I could cast those with virtually no voids unfilled. I say virtually because in order to fill all the voids, they have to have some sort of connection path to the surface in order for the resin to get in there to begin with. I have done lots of blanks like that with great success.
Click to expand...


14.69 psia is atmospheric pressure. When pulling a vacuum, it's anything less than that all the way to zero, which can't be attained. 14.7 psia = 0 in. Hg. and if you could pull a perfect vacuum to 0 psia, that would = 29.92 in Hg. which is a pressure increase. Correct?
Click to expand...

Of course I should have said IF you are able to attain 29.92" Hg at sea level on a standard atmospheric day, then when you release the vacuum you are pressure casting with the weight of the atmosphere at 14.7 psi (at sea level on a standard atmospheric day)
 
MesquiteMan said:
Vacuum would be fine IF you are using PR. If, however, you are going to use Alumilite (highly recommended for Worthless Wood casting) then you will not have enough time to pull a vacuum and release. Using vacuum is basically just pressure casting with 14.7 psi (if you are at sea level on a standard atmospheric day!) I guarantee you I could cast those with virtually no voids unfilled. I say virtually because in order to fill all the voids, they have to have some sort of connection path to the surface in order for the resin to get in there to begin with. I have done lots of blanks like that with great success.
Click to expand...

Thanks, your quote answers a question I posted in the "PRESSURE POT" post.
 
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