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Stickiness of Kapton increases over time?

Posted by Karmavore 
Stickiness of Kapton increases over time?
June 23, 2013 11:57AM
Hello, all.

I'm printing ABS on Kapton on Glass on a Heated Bed. I've done enough with my printer that I've needed to replace the kapton a couple times now, and I've made the following observations about it. I'm curious if others have noticed the same things, and if they have any suggestions about steps I can take to mitigate frustrations.

1) When I first put the Kapton on, and after cleaning it with alcohol and/or acetone, and heating the bed, there is absolutely no chance that the ABS will stick.

2) After several heating/cooling cycles, the chance that the ABS will stick to the kapton improves.

3) I enter a "happy kapton" stage, and everything just works. I clean the bed with acetone before prints, and with alcohol when I know I've gunked up the bed with my fingerprints..

4) As the kapton ages, I begin to notice that I'm having a hard time removing prints from the bed. They are stuck on but good. On the plus side, warping is less of an issue.

5) At some point, something sticks to the bed so well that I feel compelled to use an implement to get it off. I rip the kapton doing so. It's not a huge deal, because the adhesive side of the kapton had largely given up in the center of the bed anyway. Return to #1.

All comments welcome, but the questions I have are:
* What is causing the ABS to stick to the kapton better? (Heating/cooling cycles deforming the tape? Repeated acetone application collecting abs dust? Pixies?)
* Do others go through this same process?
* Should I consider a different kind of kapton? (I don't have a brand name for you, but I paid $17 on Amazon for 1" wide roll.)

Thanks for your input.
Re: Stickiness of Kapton increases over time?
June 23, 2013 01:40PM
This is the aspect of reprap where everybody has different experiences.

For me ABS sticks to Kapton very well to start with (if it didn't then I would never have discovered it as a bed material [hydraraptor.blogspot.co.uk]). It sticks so well parts are very hard to remove so I developed this: [hydraraptor.blogspot.co.uk]. Its grip then slowly fades over time until it becomes unusable.

In contrast PET tape has slightly less grip but it doesn't fade and parts are easier to remove. The glue fails eventually, or quickly when printing things with sharp corners.

Re: Stickiness of Kapton increases over time?
June 23, 2013 03:46PM
Thanks for the info, nophead. Strange that things would be so different. I wonder if ABS brand plays a role.

Over the course of this morning, I seemed to have achieve "happy kapton," so I've little to complain about. My strongest hunch is that repeated hot/cool cycles creates small deformation in my tape, because the happy kapton appears simultaneously over the entire bed, and not just where I've been printing/cleaning previously.

I'm still interested in hearing from others, should anyone be willing to share.
Re: Stickiness of Kapton increases over time?
June 23, 2013 04:44PM
My ABS gets better and better, every time I clean it with acetone it's a little less sticky, but then when I have printed a lot again, it's sticky as ever smiling smiley
Re: Stickiness of Kapton increases over time?
June 23, 2013 10:18PM
I wonder when you first clean your bed if the acetone might be leaching a little of the adhesive up through the seams smearing a slight film on the surface. Just a thought, my Kapton is wide enough to cover the entire bed so I don’t have any seams to deal with and my Kapton is consistent from first print until last. It might explain why adhesion seems to improve for you over numerous cleanings.

I do have a problem if I leave any sort of residue when cleaning. It leaves the print welded to the plate and I have to wedge a putty knife under a corner and beat it off with a hammer. Like you, sometimes the surface gets marred when removing large parts, when it gets dinged up too much is when I replace it.
When this happens the print bottom is left with a whitish haze. If you are getting any of this when your prints start sticking too well

Try this: Make sure that your acetone is free from contaminants (i.e. dissolved plastic) and use a fresh paper towel to apply it. Clean until residue builds up on the towel then fold it over and repeat…… you may have to do this several times. When you feel that it is as clean as it is going to get rub it immediately with a dry paper towel. It’s easiest to angle the plate toward a light to check the surface for any remaining film. If your temp settings are good and you keep your fingers off it you shouldn’t have to clean it again for quite some time.winking smiley
open | download - IMG_3225.JPG (223.3 KB)
Re: Stickiness of Kapton increases over time?
June 24, 2013 09:59PM
Thanks Ohm and Bruce. I sometimes shoot for the residue to get good adhesion to combat warping. I haven't ever seen the whitish haze, though.

So thus far, my small informal survey has yielded:

Me, whose Kapton gets stickier with time.
Bruce's Kapton is consistent.
Ohmarinus and nophead get less sticky with time.

More answers welcome, but the note that it differs for everyone seems bang on. I wonder if me and my wandering fingers are just grubbier.
Re: Stickiness of Kapton increases over time?
June 25, 2013 01:03AM
I didn't have any problem with Kapton tape that I bought from dx.com. It seems to me that it sticks better when the tape is new. I always avoid sticking my finger on it. If I do, I just use acetone to clean it.

I tried ABS / acetone juice on a piece of glass from a photo frame, and I then abandon the Kapton tape all together. I don't have to replace tape any more. Parts are easier to remove too. I would try it if I were you.
Re: Stickiness of Kapton increases over time?
June 25, 2013 05:17AM
The white marks on the bottom are from shearing the ABS. It goes white when it is stressed. To remove them I just use a quick blast from a hot air gun.

Edited 1 time(s). Last edit at 06/25/2013 06:40AM by nophead.

Re: Stickiness of Kapton increases over time?
June 25, 2013 03:39PM
I use the Chinese version og Kapton called Koptan.. winking smiley it works really well, but stickiness seem to increase over time.

Removing the prints from the bed is allmost impossible then it's hot, but if I wait a while and let things cool down, I can usually get the prints off with a gentle tap from a hammer, unless it is a big print.
Re: Stickiness of Kapton increases over time?
June 26, 2013 09:23AM
Ditto, except mine was labelled "Kapten"
Re: Stickiness of Kapton increases over time?
June 27, 2013 09:31PM
nophead Wrote:
> The white marks on the bottom are from shearing
> the ABS. It goes white when it is stressed. To
> remove them I just use a quick blast from a hot
> air gun.

I give them a light dusting with a mini torch. It also works great for cleaning up those pesky little white spots left behind by support. smiling smiley

open | download - IMG_3274.JPG (147.1 KB)
Re: Stickiness of Kapton increases over time?
June 28, 2013 06:00AM
Over time you may either be depositing a patchy monolayer (or slightly thicker) of polymerised ABS, or even one of the three unpolymerised ABS monomers onto the Kapton tape, as well as the tape acquiring microscopic or nanoscopic pits and troughs from heating & cooling, printing on etc, that act as invisible wells for material, which then subsequently polymerises with or otherwise bonds to your print. You will reach a point where these patches can impart enough force to cause problems but it will start to happen on the first print with a fresh piece of tape.

Nothing is infallible/a permanent solution, even polyimide tape! You could try more aggressive solvents like chloroform (don't knock yourself out) but generally you will always have to replace the Kapton tape on a regular basis. Anyone tried a teflon bed? Dissolved ABS on glass is a more controlled way of getting this phenomena, glass is generally extremely flat (down to nm) and resistant to pitting etc far more than any polymer. The ABS forms a thin, uniform layer that sticks a little, but not too much. What concentrations are you guys using in your ABS/acetone solution?

Edited 1 time(s). Last edit at 06/28/2013 06:28AM by isotone.
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