Is old body filler epoxy or polyester - how to tell?

[PeterAllen]

As the title states, how can I tell if body filler already applied is epoxy or polyester as I believe it is not recommended to mix the two?

 

 

[Sirpent]

Hi Peter

 

Fillers no matter how old will still exude a particular smell after being uncovered under paint and sanded, polyester fillers soak up solvents as they are porous, and epoxy wouldnt.

 

Sand part of the layer back and have a good smell of the paper, if it smells like filler, or a combination of filler and thiners it probably is, if it smells more like fiebrglass, then its epoxy.

 

Either way, you wont have any issues with epoxy surfaces prepared correctly as far as applying a new layer of filler over the top, personaly without knowing exactly what you are up to, Id take all the old material out and start over, one good even application of new material sanded back correcly is always better than new over old or multiple applications over one and other.

 

Cheers

 

John

[PeterAllen]

John - Thanks.

 

Whilst the body shape of my GTO is absolutely fantastic the actual laying up of the fiberglass was very ordinary. There is no gel coat, it has never been painted and there are many areas that have been patched with bog, probably over 10 years ago. I only know of three other kits worldwide of this shape and I'm unclear whether this one was a production item or built as part of the buck/mould process.  It has passed through at least four owners in Australia and goodness knows what went on in the US before that. It's a basket case.  I've previously thought of it as something of an enigma but lately it seems more like an enema!

 

I'm setting about some major fibreglass reshaping but that doesn't worry me as much as the old bog issue, there are patches of it all over the bodywork.

 

 

[Sirpent]

Hi Peter

 

Photo's can be evasive as far as showing the true state of the material in your pic, however, I would suggest that any pink material, which is clearly body filler is removed period, some of the old fillers from years back can have disasterous effects after being refinished as you just cant tell what they will do once refinished.

 

The tan colored material must be glass, I would suggest that unless the feather edges of the glass filled area's can be lifted away with a finger nail that the adhesive qualities are probably very good and removing them would probably be a worthless exercise, most applicators of glass material are usually a lot more anal about the process and I would trust them before someone with bog.

 

If she were mine, I would prep the panels having removed all the filler, seal her up in polyester spray and then do as the U.S. restorers do and rework the panels after surface checking for defects with a good body filler like a Wurth or Spies Hecker product, dry hand sand the panels back with a marine plywood block, then once surfaced re-seal the entire car in 2K Hi-Fill and finally wet surface sand again.

 

Wish I was closer to take a better look and do a panel for you.

 

Cheers

 

John

 

 

 

[Z Shop Performance]

John's @#$well right - old filler could have absorbed goodness knows what solvents over the past 20 + years. You will be shattered when your immaculately prepped surface has an awful adverse reaction when the paint is being applied. Polyester/Isolator is the best safeguard. Bear in mind that the thicker your Polyester or Hi-Fill is over you NOT CHEAP filler the bigger the chip from a stone or other impact. Bake/age your preparation , Guide coat & block it back hard before paint.

[PeterAllen]

Thanks for the comments:

 

, I would suggest that any pink material, which is clearly body filler is removed period,...

 

I've removed it all and will build up the deeper areas with matting and then Q-cell resin filler. (I'm weighing up whether to tie the laces together on a pair of trainers and throw them over the powerline out the front and sell the Q-cell powder off in small amount - I could probably buy a real Ferrari with the proceeds!)

 

...age your preparation ...

 

Never a problem with me.