"FROSTING"- help please

[wood-of-1kind]

I have been getting what I call a "frosted" look whenever I've been casting using white labels. Usually I adhere my 'pics' directly to my brass tubes that I line with a white paper label as my background. I then proceed to 'stick' my pics right on to the white label. Proceed to cast using Silmar 41 without using a pressure pot. The blanks are well cured and turn easily and well, but the frosted look prevents me from achieving that crystal clear look that I need. Enclosed is a recent cast using a clipped Porsche as my subject background. Any suggestions as what is causing the 'frosting' and more importantly, how can I eliminate it? Thanks for your input.

 

[jleiwig]

Your resin is pulling away from your picture/tube. You need a better method of securing the label/picture to the tube.

 

[wood-of-1kind]

Your resin is pulling away from your picture/tube. You need a better method of securing the label/picture to the tube.

OK, one possibility. Will the use of MOD PODGE help to better secure the picture to the tube? What you the 'experienced' casters are you using to stick your pics to the tubes?

 

[ldb2000]

You could have several things working against you , from the looks of your pictures the problem is that the PR is pulling away from the picture . This can be from either the fixative that you used to coat your pictures with is not allowing the PR to properly bond with the picture/tube or from shrinkage of the PR .
I use a spray lacquer to seal coat the picture . CA can also be used but sometimes it will cause the ink to run . Clear acrylic spray will also work .
As for shrinkage of the PR , excess heat will cause PR to shrink . Try using less MEKP to keep the heat down and don't post cure your blanks in an oven .

 

[jleiwig]

I believe the problem your having comes from having two labels on the tube. Try painting the tube white and then putting your picture on that. When you spin two labels, one sticks to the resin and one sticks to the tube.

 

[PTownSubbie]

Have you thought about using white labels rather than the clear ones? The hobby shop near me sells not only clear but white backed labels.

DAMHIKT....... LOML accidently purchased the white ones.

 

[wood-of-1kind]

Thanks for the input so far, getting some good reasons as to why I'm having the problems with the frosting effect and how to correct it.

 

[NewLondon88]

Sounds like you're getting lots of good info.. the common theme seems
to be a separation of the resin from the label. (or labels)

I've fought with the same thing .. often getting a silvery sheen in the
casting. I haven't eliminated it, but found that letting the blank rest for
an extra day (or seven) makes a difference.

Part of it might be trying to run blanks before they're fully cured. They will
harden before they're fully cured. If they're soft, it is easy to pull them
away from the tube. Just the act of turning them with a chisel can do
that, as the lathe is turning the blank and the chisel is trying to hold it
back.
That torque can pull the resin right off of the tube, or at least off of the
label. Or the stress can open up an air space between the resin and label,
and the air space changes the optics, giving you an irregular mirror effect.

Or I could be all wrong.. :tongue:

 

[workinforwood]

Mix up a very small amount of PR in a cup. Brush it on to the labels a thin coat and stand the tubes on end ..on a metal pan would be good. Put it in the toaster oven until the PR cures. the thin coat will not shrink off the labels, if anything it will shrink more into them giving you an even stronger bond. Then you can pour as per usual over that and the PR will bond to itself really good.

 

[sekach]

I have been having the same problem for a while now and just experimented with what I was using as a seal for the pictures/photo's that I was printing. I was using Testors decal bonding spray to prevent it from splitting the images as I bend the glossy paper around the tube. Today I didn't use it at all and tried photo gloss do-it-yourself inkjet stickers from Office Depot without any bonding agent. Poured clear PR from Michaels and they turned out sweet so far.....I have another experiment with the spray on laquer that I am waiting to cure right now and will try and turn tomorrow.

Thanks Butch for the idea to check the bonding agent...wouldn't have thought of that if you hadn't mentioned it....

Bob

 

[wolftat]

I too have been having some issue with this lately and am thinking that it is the humidity. After having a batch of money blanks foam up on me recently I have been holding off on any of that type of casting unless the items go into my dehydrator for a while first.

 

[wood-of-1kind]

After digesting the information that has been provided, I went back to the shop and tried another cast. The best guess is that air pockets are being introduced between the PR lining and the walls of the label(s). To minimize this occurrence, I have sealed the label pics with uncatalyzed PR (thanks for the tip Don Ward) and allowed for some curing with natural sunshine (no oven required to post cure). With my next trial I will heed Charlie's (NewLondon) advice and allow for the blanks to cure longer. Certainly getting better results, but still not totally 100% happy with the results. Stay tuned for more.