Staining when casting stamps

[sdivot]

I'm having a problem, and I wonder if anyone can shed some light. I have been trying to cast stamps, and I am getting a staining effect in spots (see pics).
The first pic shows stamps that were never uncirculated self-adhesive stamps. I simply stuck them directly on the brass tube and coated with mod podge.
The second pic shows older stamps that were adhered to the tube with mod podge, then covered with more mod podge.
I use a top coat of mod podge on both, then let cure for a couple days before casting.
I had thought at first that the self-adhesive glue on the newer stamps might be the culprit, but then it happened on the older ones as well. It only seems to happen on the ends of the older stamps, while it is on all the seams of the self-adhesive stamps.
The casts were made with Alumilite using a pressure pot.
I rough turned the blanks and polished a bit to show the problem.
Can anyone suggest a solution?
Thanks!

 

[Marko50]

That is resin getting in-between your stamp and the brass tube. You can solve this problem by sealing the ends of the tubes with CA glue after you have applied the stamps and Mod-Podge. Wait for the Mod-Podge to dry, then just make a small puddle of CA on a paper plate. Dip each end of the tube in the CA to seal it up. Don't let it soak….just enough to seal it. It usually will work, but it's not a 100% fix. …Just my .02¢:wink:

 

[sdivot]

I thought it might be an issue with resin getting between the tube and the stamp, but I wonder why, on the self-adhesive stamps, the staining occurs on the seams all over the blank. Not just the ends.
I also wonder if the resin would not creep into the seams as easily if I decreased the pressure when casting. I currently use 40-50psi. I may try reducing it to 30 and see what happens.
I'll definitely give the CA a try. Thanks!

 

[Woodkiller]

After reading many posts on casting, the general consensus is to use pr for casting things on a tube. I would think the alumalite is the problem. But as said by marko50, ca on the ends to seal it is a good idea no matter what you are casting and whichever material you are casting with.

 

[Marko50]

I also wonder if the resin would not creep into the seams as easily if I decreased the pressure when casting. I currently use 40-50psi. I may try reducing it to 30 and see what happens.
I'll definitely give the CA a try. Thanks!

When I cast "Tube-on" style items, I usually never go above 25-30 psi. When you're trying to fuse wood and resin then, yes, get your psi up around 50-70 psi in order to force the resin into all the nooks and crannies. Just make sure you're not using a cheap Chinese made pot when using pressures above 50 psi for obvious reasons.:wink:

 

[bruce119]

My experience lies with PR...

But I have seen this wetting your resin is finding it's way in and soaking into the paper...


On the second photo as Marko said CA the ends...


On the first it found it's way in...


I never had much luck with Mod Podge other using it to adhere the paper to the tube...


After gluing the stamps on I would put the blank on the lathe and give it 2 or 3 coats of medium CA...


Let it dry real good 48 hrs be sure the ends are sealed then cast...


That's how I did it...


Good Luck

 

[sdivot]

Thanks folks. I'm in the process of putting together a couple more stamp blanks for casting.
I'm going to switch to PR, go ahead and put the tubes on the lathe and add a couple coats of CA. Also, I'll be sure to seal the ends.
I'll update this post when I have results.
Thanks again!