Hi, I've been asked by one of the local riders here if i can repair his much-loved board. I told him yes, but after getting out the sander around the crack, it seems like plastic, and the company website suggests it is a PBT skin.

I know that one option is to say that the board is a lost cause, but on the other hand, it does not take a lot of effort to slap some epoxy and glass on it and see how it turns out. So, rather than doom it to failure without no good surface preparation, the question is, what is my best bet for bonding to this stuff? I guess sanding the stuff completely off might be ideal, but I'm not sure if that is possible or realistic. Coarse sanding sounds like an obvious method to improve the bond. What about wiping down with acetone or some other chemical, or even flame treating?

Anyone have any experience with PBT that they can share?

Thx,
Peter

Hi Peter,

The surface energy of PBT can be improved by a flame treatment. But normally the PBT is ok to bond even without surface treatment like flame, plasma or corona treatment. From my of point view it should be enough to do the preperation like this:

- clean the PBT with aceton. To make sure you clean it right, clean it two times, changing the paper / fabric between the two cleanings
- Sand the surface in order to increase the surface area, and also for creating a better mechanical "bonding" (sanding doesn't improve the chemical bonding)
- clean again with aceton

This should help you to create a nice bond.

kind regards from denmark
Lars

I have been told from a good source that pbt is evil. I think what Lars said is bang on in regards to the bonding though.

PBT sheets usually come with one side sintered for better adhesion. Just sticking on with epoxy might not yield good results. You are going to have to vacuum bag it.

Some more info.

viewtopic.php?t=2372086&p=728519

Thanks for the info guys. I'm not sure that vacuum bagging is necessary just for the sake of a good bond over top of the PBT skin, although I might do it anyway. There are graphics on the top of the PBT sheet. It seems that there is the same plastic feel with out witout having sanded through the graphics, so I'm thinking maybe as long as I rough it up for a bond, maybe I don't have to do large scale sanding of the graphics. Or does someone know if the graphics are anything other than the same material as the rest of the sheet?

I guess normally guys are bonding to the other side of this stuff!

Thx,
Peter

Graphics are usually sublimated and then backed, but then again without seeing what you are talking about I could just be talking shit? I picture speaks a thousand words...

When I sand it enough I get the colour off and it turns white, but is has no different feel when sanding it once it's white. I guess the question is, is that coloured stuff different from the white stuff underneath. I'm not sure how the sublimating works when they make it, and whether there is a layer of something else, kind of like paint, on top of the white plastic, which is better to remove. I could post a picture of it later, but I'm not sure how that will help in understanding whe ther the colour on the PBT is somehow different that the white base part of it.

Peter