Putty Question

I know that if you have Epoxy resin you can make Epoxy putty for sealing by adding fillers like wood flour or micro-balls.

My question is can you make the same sort of putty with Polyester or Vinyl Ester resin and fillers? And if you can make the "-Ester Putty", is it much stronger that say using Bondo or just ther resin by itself?

 

I believe fillers are possible for Polyester and Vinyl Ester but hopefully somebody here has done it before and can give you an idea of whether it works or not and what materials work best.

 

It works BUT, since the cure time for poly is generally shorter than for a laminating epoxy resin, you must either mix in the fillers quickly after catalyzing, or mix fillers and aggregates before adding catalyst. Then you will be mixing that water-thin catalyst with thickened resin, which is much more difficult. generally you are going to need a longer working time with a putty unless you work very small areas at a time.

When mixing our own fillers, we tend to just 'eyeball' it and pour and stir until it feels/looks right. Of course we are using epoxy so we have time. With poly or VE, you might want to do this 'eyeball' method on the first batch with the addition of measuring just how much of each aggregate you are adding per unit resin. When you are happy with the viscosity/ spreadability/sandability, then you have a recipe so you don't waste time 'eyeballing' subsequent batches.

You might also consider switching to a commercial marine grade polyester based filler. You must wipe the tack layer before any laminating is done over the top of these or else sand/grind. This is because these fillers will almost always be promoted for benzoyl peroxide catalyst instead of MEKPO, so the MEKPO in the lamnating resin will not cure the tack layer and thus will not bond to the bondo. There is one company, Adtech, that makes a dual promoted marine filler specifically designed to deal with this little quirk and give you the option of a short or long work time depending on the catalyst selected.

Jimbo

 

If the substrate is polyester, then you can use epoxy based putty. But not the other way around. You chances of delamination go WAY up when you use polyester. Many guys will swear that they can make a repair just as good with polyester, but the epoxy always will the contest when it comes to a secondary bond.

 

IT all works with poly and VE resins too. Q cells, microbaloons etc. The thixotropic addatives works too but you must use a specific one suitable for VE resins.