PR, CA not bonding

[Linarestribe]

What's going on here? This is a stamp pen and here is the process. I print images on Avery label paper and give a day to dry. Cut out, stick to tube, coat with CA and give a day to degas. Tubes go in resin saver and PR into heated sonic bath for 4 cycles mix in catalyst then pour. Place on drill press for vibration and everything looks great. I have a toaster oven set to 200 and a Tupperware upside down on-top as a warmer the molds go into. After about an hour I look and it seems to have separated on one end all the way around. I turned it down to get a better look. Is it the CA and does it need to be roughed up first? Did it cure to fast? Any ideas would help.

Thanks
Jorge

 

[Dorno]

I would say yes that the tube certainly does need to be roughened up so the sticker will stick properly. You also need to make sure that the ends are stuck down before you cast.

Cheers Ian

 

[SDB777]

YMMV....

I sand the tubes with 220grit, rattlecan paint, place stamps on painted tube, ModPodge(2 or 3 coats-drying in between coats), allow to dry for a few days, pour resin, toaster oven @ 140-ish degrees F.


The seperation was probably due to wet-sanding(water got under the PR), try to re-seal the ends after squaring off the blank...I use thin CA on them.





Scott

 

[bruce119]

Yea this is a problem. The ends are spots I have had and still do have trouble with. I think there mite be a few things that cause it and it's not your CA coating maybe lack of more latter. First PR is going to shrink the ends are most venerable. Too fast of curing is going to cause it cure faster more heat more shrinking more problems. I preheat PR with hot tap water probably to about 120, preheat molds to about 120, only 3-4 drops per once MEKP 'NO MORE' let cure at least 12 hours room temp. 70-80 deg.

Another thing to help with the ends make sure they are coated with CA. I go about this 2 ways. First leave some CA on the ends from the initial coating. If it breaks off puddle some CA of a piece of plastic and dip your ends in it. This will seal the ends and keep the CA from wicking in the ends reacting with the labels. Be sure to take a knife and clean the inside of the tube (for a good seal) leaving the CA on the ends.

Another thing your molds, you need more space on the ends of the tubes at least a 1/16" more is better for shrinkage. Also the plugs used to seal the ends if you get the slightest leakage the air is likely to seep up around the ends. This is why I made my own molds.

I think you can make work what you have. I think you are using way too much heat and trying to cure way too fast. If you have separation in an hour, heck mine are just gelling in an hour. I baby sit them for an hour to be sure the tubes are not leaking air. Cut your MEKP to 3 drops per once cut your preheat down a bit I don't think the sonic is necessary with just labels DON'T heat to speed up the cure keep between 70-80 deg. If your shop is cold maybe hang a light bulb or 2 over the molds.

JMHO:biggrin:
Good Luck
Bruce

 

[Linarestribe]

I think you can make work what you have. I think you are using way too much heat and trying to cure way too fast. If you have separation in an hour, heck mine are just gelling in an hour. I baby sit them for an hour to be sure the tubes are not leaking air. Cut your MEKP to 3 drops per once cut your preheat down a bit I don't think the sonic is necessary with just labels DON'T heat to speed up the cure keep between 70-80 deg. If your shop is cold maybe hang a light bulb or 2 over the molds.

JMHO:biggrin:
Good Luck
Bruce

I think this is right on since it happened during curing. I made two, a full size and jr gent at the same time. The jr came out fine and is curing much slower. The full size cured really fast. More resin more heat.

Is there any way to save this one?

 

[bruce119]

I think you can make work what you have. I think you are using way too much heat and trying to cure way too fast. If you have separation in an hour, heck mine are just gelling in an hour. I baby sit them for an hour to be sure the tubes are not leaking air. Cut your MEKP to 3 drops per once cut your preheat down a bit I don't think the sonic is necessary with just labels DON'T heat to speed up the cure keep between 70-80 deg. If your shop is cold maybe hang a light bulb or 2 over the molds.

JMHO:biggrin:
Good Luck
Bruce

I think this is right on since it happened during curing. I made two, a full size and jr gent at the same time. The jr came out fine and is curing much slower. The full size cured really fast. More resin more heat.

Is there any way to save this one?

Yes maybe

PR will adhere very well to it's self. Now in your case this may be very tricky it depends on a couple things. How large is the space if it's a fairly large void like a bubble grind away the old resin and recast. But it looks like it is just a separation very difficult depends how much CA you put on. I would turn it down almost to the paper then on the ends were your problem is carefully pick/scrape off the old resin exposing the label. This depends how thick you CA is if it will be successful. Also keep in mind what kit you are using if it is a Sierra for insentience you have a LOT of wiggle room. You can make the blank shorter and get away with it. If it is a Cigar well not much room.

"More resin more heat"

That is pretty much spot on. It's more mass more heat faster cures more problems. In other words if your doing a small thin cast like this fix you would want to double up on the MEKP. Now if you were doing a deeper cast like a 5x5 1" deep block you would use less MEKP and then there's ambient air temp.

tacky is normal after about 12 hrs. I put them outside in the hot sun for a couple hours and they cure. If it's cold out they will cure inside in a ventilated place in about 24 hrs out of the mold.

Fun Stuff

 

[Linarestribe]

I wish we that hot sun up here in the Northwest. Thanks for the tips. I'll turn down the problem spot and see if I can recast.