Fillers in Epoxy

I'm in project to build a strip-plankig 23 feet boat.

I have few information about fillers and I want to use the maximum of home-made filler for my boat.

I bought Colloidal Silica and microballoon but I'm interresting to use some easy available filler.

I try wood power from my drum sander's dust collector as wood fiber. That look well with small quantity of silica.

I try saw dust from my table saw. It is very coarse but I succeed in heavy fillet joint. It wiil be very strong (I think).

I'm looking for plaster dust. Does some one try it?

What is the 404 High-Density Filler of West System?

Do you know on which site I can find more info?

Give me your comments!!!

 

Don't know about the 404, but they're awfully cagey about talking about it, so I'd suspect you could probably buy it for a few dollars a ton if you just knew what it is.

 

Hi

as far as I remember, 404 is Aluminium Oxide.

Cheers
Mike

http://www.dauda.at

 

Using wood particles can cause you problems. For example, you may be introducing moisture into the mixture. They are probably other contaminants too. Fumed silica, chopped strands and microfibers are manufactured in controlled conditions and will consistently give good results.

 

If you are filling and fairing for sanding to get your hull ready for painting then you neeed an easy to sand mix so Microballons, Q cells or West 407 would all be ok for this. Any significant amount of silica added to the mixture will make it much harder to sand off. Silica or Cabosil etc are usually added to thicken resins when making glues to prevent sagging or the mix running out of a join.

Of course there are usually also epoxy fillers ready to go that just need the two componets mixed together so you do not need to deal with mixing a powder in too. Theyre just the right mix so it's good to apply.

 

Talc is often used as a filler, I wouldn't use plaster dust it is reactive. perlite could be used as a low density filler, just seeve it for particle size control. I have used clothes dryer filter lint in a pinch.

 

I already have Aerosil 200 and Silcell. I can find them in large bag in my area but I look for a high resistance filler. Maybe I'm wrong if I think that Aerosil 200 (fumed silica) is a good filler for is thixotropic effect but is not as strong as wood fiber or others fibers fillers ?

About Plaster like filler, I want to try dust from plaster sanding. I'm finishing 3 rooms in my house and I can salvage about 2 gallons or more of plaster dust (I'm not a good plasterman so I sanf a lot)

My purpose if for filling gap between strip planking plank with gap strip planking technics http://www.boatdesign.net/forums/showthread.php?t=6758.

 

The "plaster dust" that you refer to is drywall finishing compound. That stuff is pretty much inert, mix a small batch and try it on some scrap. I think it would be alright.

 

It is also very hygroscopic. The humidity in it will make the epoxy weak.

 

I am all for saving money too. Colloidal silica is not expensive. uscomposites.com has 10 lb sacs (this takes 6 five gallon buckets to unpack it) It takes a long time to strip plank so why complicate the process with hard too mix, not as smooth fillers?

best of luck

 

Does colloidal silica is enough as filler in high strengh area ?

It is for what I'm interresting with wood fiber, raise Epoxy strengh

 

Pure silica putties are just no fun at all to sand, but on the other hand, they tool like nothing else while wet. My concern has always been that they seem to make a very brittle filler when used on their own. I don't see any problem with using wood-powder as a filler, mix a few different recepies and glue some representative wood scraps with it. As long as you get a substrate-failure when you pull them apart, you should be good to go.

For really critical bonding operations you should always consult both a structural engineer with the right qualifications and your epoxy formulator.

Yokebutt.

 

I've found wood fiber fillers sold, generally aren't fine enough, so I make my own. Colloidal silica is a high density filler, great for fillet work, smoothness and as a structural gap filler, though is typically mixed with other reinforcing materials to improve it's workability. West System 404 is even stronger and higher density then colloidal silica.

Strip planking, by it's very nature (if done properly) should require only cosmetic filling, which can be done with a light weight, easy to sand reinforcement like 407, 410 or other microballon mixture. Any high density reinforcing filler used will make fairing quite a bit more difficult.

What are your concerns, causing you to wish for a differing filler?

 

Cost, as I understand it.

Yokebutt.

 

The cost of a failed adhesive experiment would be very high.