Which filler to use on epoxied Keels?

[seumask]

I have had my cast iron keels blasted and coated with Hemapdur Epoxy earlier this winter and I now want to apply some filler to the rougher patches over the epoxy before I prime them and anti-foul them.

What filler would the forum members recommend. Clearly it does not need to be very structural but capable of sticking to the dimpled epoxy surface and relatively easy to apply / skim on and where necessary to sand back the excess applied without too much grunt work.

I was thinking of a filler like EC 42, however not sure of its real world under water use.

http://www.ecfibreglasssupplies.co.uk/p-767-ec42-easy-sand-filler.aspx

Any comments and suggestions please.

Seumask

 

[MagicalArmchair]

I would use West System plus 407 filler (Low density filler), which is easier to sand or what I have loads of, Colloidal Silica, (which is harder to sand). I do have a tendency to over engineer things... I'm sure EC 42 would be fine, in my paranoia I would worry it would not adhere to the epoxy and fall out eventually... Seek advice from either Wessex resins or call EC fibreglass directly, they are very helpful indeed.

 

[Avocet]

I think it would definitely need to be another epoxy-based filler. I don't think much else sticks to cured epoxy. If it were my boat, I might be inclined to phone Hempel and see if they have a technical helpline where you could ask what they recommend. They must have come across this scenario before.

 

[vyv_cox]

I would use West System plus 407 filler (Low density filler), which is easier to sand or what I have loads of, Colloidal Silica, (which is harder to sand).

+1 on all counts. 407 is micro-spheres I think, doesn't provide a lot of strength but very little is needed. It is quite easy to sand to a good finish. I also have a tub of silica and have used it a lot with West epoxy for attaching furniture and bulkheads to the hull. It is quite a lot more difficult to sand down, although not much resists an angle grinder. http://www.westsystem.com/ss/407-low-density-filler

 

[MagicalArmchair]

Oh, and one more thing, beware the amine blush and epoxy lest all your antifouling may fall straight off! I don't know if Hemapdur blushes or not (as Avocet said, contact Hempels), but I'd be inclined to give it a good wash down with soapy hot water before I did anything. West system certainly does blush, so before you prime and antifoul, wash the blush off (again, very easy, just soapy warm water) after your epoxy filler has cured...

 

[VicS]

Something easy to sand would be more sensible than something that requires a grinder or you'll be taking off the Hempadur again before you know it!

 

[rogerball0]

+ 1 for 407 and also used 404 on the leading edge / sole:

Before

During

After

 

[ghostlymoron]

There was a thread on here recently on whether it was worth spending a lot of time treating rust on keels. I think the conclusion was 'no' as any system will breakdown in time and its cosmetic anyway.

 

[rogerball0]

There was a thread on here recently on whether it was worth spending a lot of time treating rust on keels. I think the conclusion was 'no' as any system will breakdown in time and its cosmetic anyway.

Thats a good point GM, my keels started cracking along the tops where there is a casting void from just being sat outside, so ended up vacuum bagging them with three layers of 450g Bi-axial cloth:

Before

& After

Keel Build log here:

https://picasaweb.google.com/110182886418433827802/KeelsOct2008Apr2013#

 

[MagicalArmchair]

Dude, that is pure artistry. Love the man cave too! You did well to get the 450gm GRP to go around those corners on the top of the keel, did you get any lifting off? (apologies for thread drift)

 

[vyv_cox]

There was a thread on here recently on whether it was worth spending a lot of time treating rust on keels. I think the conclusion was 'no' as any system will breakdown in time and its cosmetic anyway.

Cannot claim results of the calibre of rogerball0's super job but my keel has been grit-blasted, epoxied and faired twice, each time lasting 10 years or more. The first one failed badly during a winter afloat after about 12 years, the next one is up to about nine years now, still holding on but some rust spots appearing. It may have to be re-done next year.

 

[rogerball0]

Dude, that is pure artistry. Love the man cave too! You did well to get the 450gm GRP to go around those corners on the top of the keel, did you get any lifting off? (apologies for thread drift)

Hi Mark, and thanks, you cant really see on the pics but the edge of the new mating surface i made was around 5mm higher than the body of the keel so all i did was hand sand a 1/4" round-over along that edge and vacuum pressure did the rest. I vacuumed the body of the keel whilst suspended and did the top with it sat in the steelage, a two part affair.

I should of said seumask that this whole job was made easier using shovel fulls of cabosil (colloidal silica) in the epoxy then sanded back using a 1/2 sheet sander and 40 grit sandpaper, doing "union-jacks" to keep the profile although i did make a series of templates to keep me on track.

+1 also for East Coast Fibreglass, you wont find a more knowledgable, helpful group of people out there regarding all things fibreglass.

 

[Ric]

I have had my cast iron keels blasted and coated with Hemapdur Epoxy earlier this winter and I now want to apply some filler to the rougher patches over the epoxy before I prime them and anti-foul them.

What filler would the forum members recommend. Clearly it does not need to be very structural but capable of sticking to the dimpled epoxy surface and relatively easy to apply / skim on and where necessary to sand back the excess applied without too much grunt work.

I was thinking of a filler like EC 42, however not sure of its real world under water use.

http://www.ecfibreglasssupplies.co.uk/p-767-ec42-easy-sand-filler.aspx

Any comments and suggestions please.

Seumask

I would suggest as somebody else already has, to use epoxy filler. I stripped my cast iron keel, applied about six coats of aluminium-rich epoxy, then faired it with epoxy filler, then put another few coats of aluminium epoxy over that, and then finished with coppercoat (also epoxy based). So far it has lasted five years without a trace of a blemish.