respray disaster :(

[Adam G 1330]

Im in the last stages of a restoration / respray that has taken me 3 months now (full time) and im noticing small bubbles appearing behind the new paintwork (3 weeks old). This in on areas with serious rust throughs which i cut out the majority of the rust, sealed the area from behind with fibreglass (using epoxy resin for higher flexibility, adhesion and water proofing) ( i did this well being very experienced with fiberglass). Then vactanned the outside, fillered smooth and primered and painted with 2 pack. In areas with surface rust i simply sanded, vactanned fillered and painted. Thinking no oxygen and water is getting through either fiberglass or 2 pack paint right? (well for several years). I feel absolutely gutted cos the thing is looking amazing having just finished wet sanding and polishing it to a great finish and now Im imaging rust bubbling through all these areas i fixed, What else should i have done? / could i redo in the future (which looks pretty short term) when the rust returns?

Cheers

[CovKid]

Unless you get to both sides of any rust, it will return. Seams need sorting both inside and outside. Not sure I'd opt for fibreglass unless whole body was made of the same. Never had any success with it in such an application in 25 years except as a temporary bodge.

[lloydy]

unfortunately, i'd say you'd have to get rid of rust completely before painting otherwise its bound to come back

[Oldiebut goodie]

Paint incompatibility with primer?

[New Kentish Campers]

Can you put a few close-up pictures of the problem?

It could be micro-blistering by the sound of it, and that's often caused by spraying pint in an unheated garage/or primer that hasn't cured properly, particularly if you've been wet-flatting the primer.

[delinkwent]

i agree with KNT - get some good pics up - where are you spraying, what are the conditions like?

most likely causes are not cleaning the surfaces well enough before laying primer or paint (small amounts of contamination from sanding water or sweaty hands), not allowing enough time for evaporation between coats, spraying in cold or damp conditions, or having a rubbish water trap

to prevent clean thoroughly before laying anything and allow enough time for water to fully evaporate after wet sanding (a couple of hours at least)

it is salavagable, just flat back to a good substrate - you may need to go back to bear metal in places

hope this helps you

cheers, billy