Hi guys,

I had a few experiments to cast a rubbing strip for oldtimer bumpers (middle of the bumper).  So these cars aren't outside for months, but strip needs to be sort of weather proof


So I bended a aluminium for mould, shape is perfect.

After using some casting rubbers (including UV stabilisator) I keep having strange complications.

UV really kicks in after 14 days:


strange spots after rain:

color fading away after 14 days


is there someone who can point me to the right (easy comp) kind of product?  needs to be a little flexible / soft ...

thanks in advance !!

You really need a UV stable resin by the looks of it.  Certainly a strange reaction there. I would expect fading or maybe some kind of surface degradation but that is quite unusual.   Are you sure the product was fully cured when demoulded?  Moisture absorption and damage like that is usually seen on resins that have not cured properly.  Most resins, once fully cured would certainly be waterproof in terms of rain fall and spray on a car.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

ok, might make another one and let these one cure longer?   the resin was 24H in the mould like asked (the pix are 2 different resins).  after that I left it outside for a few weeks.  looks mint when strip is dry.  when it starts to rain, color changes ... 

If it is not fully cured, it will still be hydroscopic. 24 hours may be fine for demould but, like most resin systems, the tail end of the resin cure may be longer.  I would leave it a good week to fully cure or do a post cure in an oven before putting outside.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

ok, thanks for the advice Warren.  is there a easycomp resin - product that suits the specs i need? 

Our flexible PU's are not 100% UV stable so you may still suffer from pigment fade over time. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

UR 3450 Sika