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[follow3]

Hey All,

I tried casting some tubes that I had powder coated.

I used high gloss black PC on the tubes, they looked awesome.
I glued corks in the ends, then glued the corks to square pieces of wood. Next I put them in my mold and mixed up the resin.

I used Silmar 41. 4 drops of catalyst per ounce. Degassed before I poured. Poured them and put them in the pressure tank for about 20 hours.

When I took them out, they looked great. I went back to get them ready to turn a couple of hours later and...

They look like there are air pockets between the tube and the resin. Not bubbles, larger spots, allmost like the resin is starting to seperate from the tube.

Any ideas what went wrong?

The only idea I have come up with is maybe I should have used flat instead of gloss powder coat???

Any help would be greatly appreciated!!!

Steve

 

[stevers]

I had a little trouble getting the resin to stick and stay on gloss PC. Thought about roughing the tubes a little before casting. Anyone else had this problem. Lee, what do ya think?

 

[OKLAHOMAN]

Question. Is the air pocket close to the cork? I've had at times air pockets next to the cork,almost lines of void. I think air is escaping from the tube thru the cork. Some of the corks have voids that would allow air to escape. Two ways to solve this:1-coat corks with med. CA before use 2: wrap the corks with electrical tape before inserting into tubes.I've had success with both methods. Hope this helps..

 

[Firefyter-emt]

Well, there is a chance it's the cork. I have bought the rubber cork / plugs, but to be honest I am still waiting to get some of those hand painted tubes finished before I cast the clear and PC tubes. The PC should not be problem over paint and I personaly would not sand them. The "close up" view you get may show the sanding twice as bad.

I saw switch to a rubber cork first and see what you get.

 

[SteveCzar]

I have had this same problem using alumilite. The tube is seperating from the resin causing air between the resin and the tube. After its casted it looks great no air at all, but once pressure is put on the tub you start getting the air pocket look.I am going to try and ruff the powder coating up first with a scotch bright then cast. Anyone else have any ideas ??

 

[rherrell]

This may be a stupid question but why do you PC the tubes? I just use spray paint and haven't had any of the problems you're describing. Wouldn't PC be overkill? Seems to me that since you're encasing them in resin anyway it would be. I do grind the corks down to almost nothing though before gluing on my spacers. Maybe that helps?
I grind the corks down so only about 1/32" is showing. When I glue the spacers on with med. ca and it covers the end of the tube and effectively seals it up.

 

[Blind_Squirrel]

I had a 100% failure rate with Alumilite when I tried to cast it directly onto the tubes. I have had MUCH better luck (90+% success) with PR.

How much pressure are you using? My theory is that if you use too much pressure you compact everything, then when you release the pressure the tube shifts and releases from the resin.

My best success has been degassing the PR resin using an ultrasonic cleaner and casting with about 20 PSI pressure.

Walmart has some rubber knitting needle caps that I use to cast Sierra and larger pens. I found these to be far superior to corks. If you are careful with removinting them they are reusable.

 

[BRobbins629]

More than likely this has to do with the surface tension of the powder coated surface relative to the casting resin. Degassing and/or higher or lower casting pressure has nothing to do with this type of void. Degassing and pressure only affect dissolved gases in solution. While not all powder coating materials are the same, the analogy is like pouring water on a just waxed car where the water beads up. IMO same thing is happening at the PC tube surface. Although I haven't tried this, one technique used in the printing industry to change the surface energy would be to use an oxidizing flame on the coated tube. You wouldn't need much, only enough to affect the very surface layer of coating.

 

[SteveCzar]

i powder coat my tubes so i can do different color background to what ever kind of picture im putting on it and by powder coating you sure wont get a tube to break free like ihave happen with paint. I should have known better since i work with all kinds of resins everyday in my kinda work, and like most resin you need to scuff the surface for it to stick.

 

[its_virgil]

Steve,
Why did you powder coat the tubes? There may be a better way to achieve what you are trying, but we don't know where you are headed. Do you just want black under the clear resin?

edited in: Listen to what Bruce Robbins has to say. Like Rich Herrell I too paint the tubes so labels will stick better and I get no color shift from the brass tube. Scott (Blind Squirrel) also has excellent info about the ultrasonic cleaner and 20 psi. I started using the ultrasonic cleaner and I will never go back to what I was doing. Thank you again Burce! The PR seems clearer than it ever did prior to using it. Are you painting on the tubes or using labels? If painting, maybe some other undercoater should be used...I think gesso or something similar may be a good choice. Good luck.
Do a good turn daily!
Don

Originally posted by follow3

Hey All,

I tried casting some tubes that I had powder coated.

 

[SteveCzar]

Virgil , i have used labels to put pictures on a tube but i got tired of hiding the seam.I hafve paintd my tubes for adding colors behind a pen blank. I powder coat my tubes different colors and apply decals to them, such as pictures Ect. I did find out that the powder coating is to slick for any type of resin to stick to including alumilite and PR. So what i did was use a scotch bright and just scuff the surface to remove the shine then cast, it worked just great using alumilite. To test it i tryed making the resin break free of the tube or to make the sir bubbles between the resin and the tube , well after some hard hits the resin came off the tube taking the powder coating right off the tube. So by using powder coating i can get aot of great colors mixed together and make some cool looking pens not to mention making a pen kit any color i want also.
So Follow3 and Stevers give this a try, Stevers let me know how it works using PR since im out of it and havent tryed it yet.

 

[follow3]

Virgil,

I am PCing the tubes because I have had trouble with paint seperating from painted tubes. I am using decals to decorate the tubes and then casting clear over.

SteveCzar,

Have you had any problem with the scuff marks showing in the finished product?

I tried again this weekend with the same results. Another thing I realized I may be doing wrong: I have been using surfacing wax. I think this may also be causing a problem. The blank I cast yesterday accidently got a little more surfacing wax than normal and when I tried to get the remaining cork out, the tube actually moved. The resin didn't adhere to the tube at all.

When I get some more decals, I am going to try again without the wax, scuff the tube, and use less pressure. I will let you all know what happens.

Thanks for all the input everyone.
Steve

 

[SteveCzar]

Follow3

Sorry for not getting back sooner. No i dont have any problems with any scratches showing, a gray or green scotch pad just takes the shine off. I found to after you put your decal on the tube give it a spray of clear again. My only problem i get is the decal lifting in the center or near the edge of the picture where it gives an air bubble look. For some reason they arent staying down after i cast them. Im working on that one now.