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Old 17-09-2009, 20:45   #1
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West Systems 407 Filler Question - Please, Please HELP!

Hi everybody,

I am helping a friend redo the deck on his 46 foot sailboat. He used to have teak, but became tired of the upkeep. He tore out the teak and pulled all the screws. My job for today was to clean out & refill all the holes left behind from the screws in the wood, and to grind out, clean and fill the small cracks and voids in the deck/cabin joint. I used 406 colloidal silica for all the holes on the deck. Did all the proper prep work and everything. But For the small gaps in between the deck/cabin joint I used 407 fairing compound. I cleaned them out really well with solvent, then brushed on some mixed epoxy and then filleted in the fairing compound nice and evenly. Long story short...I got a call from him today saying that the fairing compound is no good for that job. That we need an adhesive filler for that job like 406.
So I'm gonna have to grind it all out tomorrow and redo it with colloidal silica. Is that necessary? I didn't think that those little gaps needed very much adhesion or structural support, but we are both very new to fiberglass work. The little voids I filled are no more than half inch deep, and less than a quarter inch wide.
I would greatly appreciate anyone's personal experience or knowledge. I want the job to be done right, but don't want redo all that if it isn't necessary. We wanted to paint this weekend.....

THANK YOU, THANK YOU, THANK YOU for your advise.
Amigo
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Old 17-09-2009, 21:44   #2
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What are the gaps?
If you pulled up the teak, what was underneath that had gaps?

Will it be glassed first?
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Old 17-09-2009, 21:50   #3
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Amigo,

You should have used a syringe or caulking tube to inject the mixture so that it gets all the way in without trapping air. I would have used a filler mixture of 50% coloidal silica and 50% microfibers for that, or, if a fillet was wanted, just colloidal silica because microfibers don't make pretty fillets.

The 407 is a low density filler. It gets 1 out of 4 stars for bonding and 3 out of 4 stars for bonding with fillets. The latter mostly because it makes pretty fillets. The bonding part is what hurts because high density filler (404), colloidal silica (406) and microfibers (403) all perform 3 times as good for structural gap filling and strength.

So, I am afraid your friend is correct in this case. If you want to fill the gap and use excess for forming a fillet, 406 colloidal silica is the best choice. I would use it on a vertical plane anyway, or mix it into other fillers, for it's non-sagging properties.

If you want to speed up this job, find a quick way to remove the 407. A Fein multimaster with the right blade makes short work of it. For applying the 406 mixture, get a couple of fillable (empty) caulking tubes (for use in caulking gun) from West System. Work quick, make the mixture, spoon it into the caulking tube, insert nozzle all the way into the gap and fill a couple of inches; try to form the fillet with the excess; adjust amount of mixture injected to create a good fillet and then keep going along the gap while the 2nd man forms the fillet. I never try to re-use these tubes.

It is important to make this strong so that no cracks appear later. It is also important to prevent voids, not only because it weakens the deck-cabin joint, but also because it's a place for water to accumulate after a crack provides access to the weaker spot.

cheers,
Nick.
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Old 17-09-2009, 22:12   #4
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Fillers

Don't waste you time grinding out your work. If you were doing serious structural work that was going to see high compresive loading you would want to use the stronger filler, ie. liquid shiming under a very large windlass or possibly a construction crane. But for the work you describe (filleting the cabin/deck joint, filling cracks and holes) the 407 should be more than adiquate. The 406 is billed as sylica which I take to mean solid particals of sylica (the main ingredient in glass, basicaly specialized sand). The 407 is micro balloons of glass (sylica only hollow) which makes it lighter and addmitedly with less ultimate strength but for the application you describe it is still more than up to the job. I have worked in the comercial aerospace biz for 22 yrs. and have done many a surface repair on external secondary structeral aircraft surfaces (wing to body fairings, access doors, landing gear pods etc.) using basic epoxy resin with glass micro balloons for filler as standard practice. The only time toughend epoxy compounds using powdered aluminum or other solid fillers was recomended was in situations where through bolts or other high external loads were imposed on the repair areas. Stronger is usually better but when you are already well beond what is required you shouldn't create work where you don't need to.

My .02
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Old 18-09-2009, 00:45   #5
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Marksman,

Your comments about colloidal silica (you mistakenly call it silica) show that you never used the product or at least you weren't aware of it. It is a fumed silica, made by vaporizing sand (it's the "smoke" that's left when you vaporize sand). It is a thickening agent, a desiccant and with abrasive qualities too, used in milk shakes, dense & polished concrete and toothpaste to name some. For bonding, it is much stronger than microballoons, no comparison.

Microballoons are made by heating tiny droplets of dissolved waterglass (sodium silicate) and are much bigger (say 2,000 to 20,000 times as big as colloidal silica particles) and very fragile. They are so fragile, that by mixing them into the epoxy, up to 80% of the microballoons break. That is why many stopped using them and switched to the microlight filler.

For casting bases for winches, you need a high density filler (404). I have never seen colloidal silica used for casting bases for construction cranes; I think they use concrete for that but sure they might mix it with colloidal silica, I've never put up construction cranes ;-)

The deck to cabin joint is very structural, as much so as the deck to hull joint. When this joint fails, the hull collapses. These gaps, cracks or whatever they are, are 1/2" deep and 1/4" wide, you are borderline between filling&filleting and filling plus glass reinforcement. If these gaps are over a substantial part of the joint, I would opt for at least a 2" fiberglass tape applied over the filled joint, even with all the hassle of fairing that out onto deck and cabin. The gap will be in compression when the hull-side is pressed inwards, the deck withstands that and transfers this load to this joint. As the cabin-top goes vertical upwards, the gap will be compressed.

Your experience in aerospace describes non-structural applications where microballoons indeed work well, like the fairings, landing gear pods etc. But you would never use it to flll a gap between wing and fuselage.

ciao!
Nick.
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Old 18-09-2009, 07:14   #6
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I like the West System and have been using it since 1991 but have tended to use the microballoons only for apps needing less strength. The advantage of that is that it can be easily sanded. I always coat the area to be applied to with a coat of straight epoxy, use the microballoon/epoxy mix, sand, then use several coats of straight epoxy after sanding.
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Old 18-09-2009, 08:20   #7
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TexSail,

That is exactly where microballoons are meant for. You should give the micro-light filler (410 I think) a try, I like it much better than the microballoons but it is less resistant against heat so never on dark paint that gets the sun. It is, like micro-balloons, a fairing filler.

cheers,
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Old 18-09-2009, 08:37   #8
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Guess I got some more scrapin & grinding to do today then....
Thank you all so much for all your help and advice.

Amigo
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Old 18-09-2009, 09:07   #9
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Jedi (Nick) is spot on again. I like your idea of pre-wetting with unthickened epoxy first, then using a combo of microfibers and colloidal. BE YE WARNED! This stuff sands like STEEL! clean up and fair all you can before it goes off. BTW, you can buy all this stuff, non-WEST brand at Jamestown, and save a bunch. Boat Building and Woodworking Supplies
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Old 18-09-2009, 09:45   #10
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West Systems offers excellent tech support over the phone. Give them a call and explain what you have done and your concerns. Everytime I have called I have learned something I didn't previously know that improved the project I was working on.
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Old 18-09-2009, 14:59   #11
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Chris,

The microfibers make no nice fillets so I leave them out when I want to use the same mixture for both bonding and filleting (with the excess mixture from the bond). For laminating it's the other way around, I use only microfibers to ketchup consistency and apply with a notched spreader. An hour ago, I laminated a new shelf for the new A/C unit (old one rotted and delaminated ;-). I like to keep some 1/4" thick plywood around which I can use for anything, laminating it for thicker parts. Often, I just laminate some 1" wide strips around the edges of a panel, leaving the rest 1/4".

The wet-out with resin+hardener mixture is important. Without it, you risk resin starvation as the capillary action of the wood sucks it all up. Wait 30-60 minutes before applying the bonding/laminating mixture. You can shorten that when you see all the resin is absorbed already.

ciao!
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Old 18-09-2009, 15:33   #12
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Just go with straight 406 (colloidial silica). It'll be strong and come out pretty. Microfibers are nasty and impossible to sand.

I've used the emppty caulk tube and it works great ( a full tube will be too much and you'll smoke it from the epoxy reaction)
jamestown distributors sells them.
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Old 18-09-2009, 15:55   #13
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Messy syringe...

I got a box of large 50ml syringes from my friendly epoxy seller when I was working out how best to measure epoxy. (Now I use a syringe for the hardener and plastic cups from the supermarket that I graduate myself.)

It's easy, if a little messy, to fill the syringe with epoxy whatever mixture and to squirt it into a hole. Rubber gloves help keep the mess off hands.
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Old 18-09-2009, 22:37   #14
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S&S: the trick is slow hardener and cooling the resin before mixing it. And yes, it's hard to go wrong with the 406.

Boracay: When working with epoxy, think of it as a surgical procedure, working as clean as possible, preparing everything as good as possible. The trick is that even though this costs time, you finish much quicker in the end because cleaning up (sanding..) takes so much more time.

I can mix a batch from just resin&hardener up to a ketchup consistency and apply it with a syringe without any cleanup other than wiping off the mixing stick afterwards, without using gloves. Normally, the first time I get epoxy on my fingers is when testing it for cure (I am not very patient ;-)
It is a discipline that I picked up from a Dutch West System distributor who is now skippering his own charter operation ;-)

cheers,
Nick.
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Old 19-09-2009, 06:30   #15
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I was fairing last night, and looked down at the label on the tub of phenolic microballoons, which I have never read before. Right there before my eyes was the answer: "Do not use this filler to prepare a glue!" Well, that 'bout says it all...

As for filleting, straight colloidal, balloons, or wood flour, all can be made smoother with a tool (or finger) cut to the right radius and wet with lacquer thinner. Just don't make your mixture so darn thick that it makes the job impossible and is resin starved itself...
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