epoxy additive for keel filling

[laika]

There appears to be a rusty little dent in my (iron) keel (quite small). I intend grinding it back with a wire brush on an angle grinder, applying some rust converter, then filling with epoxy. The book I have suggests microballons as an additive for this task (presumably for ease of sanding) but elsewhere says not to use microballons below the waterline because they are porous. I'm presuming for this application it's OK because I'm not trying to make anything watertight but just checking in case the epoxy is actually supposed to"seal" here. And also a little bit because I have colloidal silica and low density filler and the smallest quantity of microballons I can buy here (a small bucket) is over a tenner and I'm a cheapskate...

 

[prv]

I don't reckon it really matters what you thicken it with. You just need something to turn the epoxy into a paste rather than a liquid. Silica (for anti-slump) and low-density filler (easier to sand than microfibres etc) sounds like a good mix to me.

Pete

 

[VicS]

There appears to be a rusty little dent in my (iron) keel (quite small). I intend grinding it back with a wire brush on an angle grinder, applying some rust converter, then filling with epoxy. The book I have suggests microballons as an additive for this task (presumably for ease of sanding) but elsewhere says not to use microballons below the waterline because they are porous. I'm presuming for this application it's OK because I'm not trying to make anything watertight but just checking in case the epoxy is actually supposed to"seal" here. And also a little bit because I have colloidal silica and low density filler and the smallest quantity of microballons I can buy here (a small bucket) is over a tenner and I'm a cheapskate...

Obvious question , why bother.
If you dont get back to clean rust free metal and seal it gain befre any surface rust forms you will be wasting time and effort anyway.

There is loads of good advice on the Wessex resins website. Scroll down this page to some of the detailed guides http://www.wessex-resins.com/westsystem/use-guides.html

Id think one of the high density fillers would be the most appropriate. You will be able to grind it down to the correct profile, not have to be able to sand by hand.

If you have colloidal silica use that !

 

[30boat]

You can use sawdust or even flour.I use Talc many times.

 

[nimbusgb]

Microballoons, easy to sand back but completely water proof. Not like cotton, flour, talc or such like.

 

[30boat]

Microballoons, easy to sand back but completely water proof. Not like cotton, flour, talc or such like.

Once mixed with epoxy those additives become completely inert.

 

[jakeroyd]

I did mine with epoxy putty.
easy to mix , two bits you just mix up and apply.

it's quite stiff so it stays in the hole whilst it cures