Stuff you add to epoxy....

[Thermo]

Getting closer to start time, and now I want to make sure I have my epoxy additives straight here. Maybe some of you can help connect the dots between the additive and the job.

The additives:

Silica, carbosil, etc.

Wood Flour

"Microballoons"

"Microspheres"

Solvents (thinning)

Nothing (straight epoxy)


The applications:

Gluing

Fairing

'Payson' butt jointing

Filleting

Painting on right before glass sheathing

Applying over glass sheathing to fill the weave

Applying to wood that won't be glassed, just primed and painted (interior bits mostly)

Filling in gaps from epic sawing errors.

Adding a tangy flavor to ham sandwiches

[Canoeyawl]

ADHESIVE FILLERS

403 Microfibers
403 Microfibers, a fine fiber blend, is used as a thickening additive with resin/hardener to create a multi-purpose adhesive, especially for bonding wood. Epoxy thickened with microfibers has good gap-filling qualities while retaining excellent wetting/penetrating capability. Color: off-white.

404 High-Density Filler
404 High-Density filler is a thickening additive developed for maximum physical properties in hardware bonding where high-cyclic loads are anticipated. It can also be used for filleting and gap filling where maximum strength is necessary. Color: off-white.

405 Filleting Blend
This strong, wood-toned filler is good for use in glue joints and fillets on naturally finished wood. It mixes easily with epoxy and lets you create fillets that are smooth and require little sanding. Its color is a consistent brown, so 405 can be used to modify the shade of other WEST SYSTEM fillers.
http://westsystem.com/

[abbyj]

Getting closer to start time, and now I want to make sure I have my epoxy additives straight here. Maybe some of you can help connect the dots between the additive and the job.

The additives:

Silica, carbosil, etc.

Wood Flour

"Microballoons"

"Microspheres"

Solvents (thinning)

Nothing (straight epoxy)


The applications:

Gluing

density dependent. Phenolic Microballons with a touch of colloidal silica produces a glue line in western red cedar/spanish cedar, that exceeds the grain strength of the wood. Where as this combination of fillers would be questionable for another softwood like doug fir.

Saw dust, microfiber, and cabosil can be used for many gluing situations, depending on the strength requirements. Microfibers good for big gaps, and colloidal silica can also be used for the big ones. Saw Dust can be used for thinner lines, but there are too many variables and oils in the sawdust (at least shop-gathered) to really know if it will work well or not.

If you could only have one filler, Colloidal Silica (Cabosil) will cover most of your gluing requirements.

Fairing

Microspheres (AKA Hollow Glass Microspheres) is a really lightweight faing additive. Sands easily, and is strictly a fairing filler or for creating non-structural filets.

Phenolic Microballoons is a little bit heavier than HGM, and it's easily sanded when mixed thick.

'Payson' butt jointing

I've never done anything with Paysons Butt, let alone jointing it

Filleting

In my opinion, a Phenolic microballoon mix "fattens"up the epoxy and properly blended ( experiment, MB's can go from seeming too thin to smokin hot mass of gouge in no time ) It spreads well and goes a long way, although by itself, should only be used for non-structural (easy clean interiors) Think caulk.

Cabosil makes a good structural fillet, but it's "sticky" (hard to explain) texture can get annoying. Cures very hard

Microfibers can be used, but it will be a "chunky" heavy textured filet. However, a brushable (thin) mixture of a lighter weight filler painted over the filet before it kicks can make additional surface prep easier. Microfibers will need grinding wheras a microballoon or spheres mixture painted of it will only ned sanding or a 7447 scrubbing

Painting on right before glass sheathing

Best if possible to do a dry-layup ( glass over the surface then wetted out with "neat" epoxy

Applying over glass sheathing to fill the weave

Additional coats of "neat"epoxy will fill weave

Applying to wood that won't be glassed, just primed and painted (interior bits mostly)

You can just prime and paint. below waterline, a minimum 2 coats epoxy then just paint (unless you want to fill any imperfections, then use a high build primer before you paint)

Filling in gaps from epic sawing errors.

On critical elements, open wallet and stuff green paper in the drawer of the local lumber yard.

Otherwise, stick to fibers and cabosil

Adding a tangy flavor to ham sandwiches

Check the joint of Payson's Butt
[/quote]

[George Roberts]

I find wood flour (saw dust) is the only filler I need.

[Daydreamer]

Don't know of any solvent to thin epoxy. Thought this would not work under any circumstances.

[JimD]

What's all this talk about sawdust? What kind of saws are you guys using? I thicken with sanding dust. Saw dust gets thrown away.

[Steve Lansdowne]

You really ought to get the System 3 manual or other epoxy related book to understand what this is all about. It is wonderful stuff, but you need to understand it to avoid common errors and making a mess of things, not to mention your health.

[John B]

You can pigment your brew of choice too. Graphite to make black etc. Buy the powder you find at construction outlets for tinting concrete for example.various colours.
One blindingly creative approach I no doubt re invented was to use nescafe for a nice dark brown mix I needed for some smallish job.

[abbyj]

What's all this talk about sawdust? What kind of saws are you guys using? I thicken with sanding dust. Saw dust gets thrown away.

sawdust is shavings and dust. Dust cakes the upper filter cannisters while the shavings and chip fall into the drums

[Dave Carnell]

Talc is a superlative filler that sands easily. Best source is generic baby powder, just check that label says talc is the ingredient, not cornstarch.

[jimmy lee]

I use West System. I mix in sanding dust from my sanders,for thickened epoxy,and for making fillets. Works Great people!!! I've had success building two boats.

[rbgarr]

Make a mixing tub to avoid breathing in additives: a vacuum attached to the bottom of a garbage can with a hole in the low side below a screen that your epoxy pot can sit on. If it's done right it will suck whatever you don't stir in away from you. Use respirator also, of course.

Cabosil is very bad stuff and will get away from you.

[paladin]

I've used nothing except industrial talc, microballoons and sanding dust since the 60's and have found no need for anything else.

[abbyj]

Another cheapie filler is diatomite pool filter media. 5$ for a lifetime supply.

[George Roberts]

"What's all this talk about sawdust?"

I use a handsaw on my bench. The same bench I hand plane, hand chisel and hand sand on.

The sawdust, chisel waste, and sanding dust are all mixed together and called sawdust. Sometimes I pull out the really large stuff. Sometimes I don't.

[paladin]

The simplest way is to use two clean 5 gallon buckets, cut the bottom from one, add ordinary windo screen, set the bucket inside the non cut one, toss all sawdust/sanding dust in the top bucket...voila! graded fines out in the bottom bucket. No power saw was used in building my 44 footer, but no teak dust was intentionally added to the mix, just the ash/mahogany/rosewood etc...

[Tuck' Sailin]

westsystem.com

[hansp77]

adding yellow powdered Turmeric acts like fine woodflour and gives the epoxy a brilliant red colour that matches bright red stained timber.
John B's suggestion of nescafe made me think of finely ground turkish coffee as a woodflour substitute for filling black or dark timber. The oil in the coffee might be a problem though.

Short story, if I am not reaching for the WS microballoons or silica glue stuff- then I am ferreting around in the kitchen cupboards

[Tuck' Sailin]

If you use epoxy and such that requires a squirting thing, make sure your first squirt goes in the bad cup. It takes one small amount to be missing and your project is ruined. I learned the hard way.

[Carlsboats]

Don't reinvent the wheel. No need to cook up your own filler system. Go with the basic manufacturers' recommendations. I use System Three. Lots of people swear by West System. Both have years of experience with fillers for hundreds of applications, and they know tons more about this that us amateurs ever will. So I say, get one of their manuals or talk to their tech. service people, and do exactly what they say.

[hansp77]

If I am gluing something crucial on my boat I use the WS glue additive, if I am filling something crucial on my boat I use the WS microballoons-
however, I use epoxy for a ton of other little non-crucial things.
The use of powdered turmeric was to fill in the holes from some countersunk coach head bolts that I mounted my wood bench vise with- the bench aint fancy, its just a recycled old fruit/veg shop stained ply-wood counter- but it was an experiment that worked- for extents and purposes I could have filled it with chewing gum.
I do foresee trying some powdered turkish coffee next time I wish to fill in or glue some dark wood (restoring a hand tool handle or something). I tried using 'sawdust' and found it to be nightmare- too non-uniform. Sanding dust is a bit better if I can collect enough good quality stuff- but then that is probably contaminated with sand paper...
Turmeric looks awesome in epoxy- the colour change is dramatic- it stains it red- I have considered doing a casting out of it

I am not (I and I am sure no-one else is) saying to try using pwdered baby food (etc) as a filler when gluing up a mast- but there are many applications where one may try what they want.
Reinventing the wheel is fun sometimes, especially when it can't hurt.

[Keith Wilson]

Well, I'll take a stab at this. I'd recommned System 3's Epoxy Book. It's probably the best single basic resource. You can download it here: http://systemthree.com/members/liter...Epoxy_Book.pdf
The Gougeon Brothers' book is good, but far, far more detailed than most folks need.

OK: There are basically two things fillers do; the functions overlap:

1. Make epoxy more viscous and thixotropic (not runny, more like a gel), so that the goop will stay where it’s put. These are not the same thing, some fillers do both.

2. Add bulk to reduce epoxy use, since fillers are cheaper than epoxy.

Silica/Cabosil makes the mix thixotropic and adds only a little bulk. It’s strong, hard to sand, and looks ugly if not painted. Use it for gluing or fillets.

Wood flour adds viscosity and bulk; use for gluing or fillets. It’s fairly strong, easier to sand and looks a little more like wood. Use it for gluing or fillets. Wood flour-epoxy mix tends to run even when quite viscous, so for general purpose goop, I like a mix of sanding dust because it’s free and a bit of silica to make it more thixotropic. Viscosity varies with the ratio of filler to epoxy.

Microballoons/microspheres add a lot of bulk and viscosity and make the mix thixotropic as well. They are quite weak (they’re essentially small bits of nothing with a very thin shell around them) but very easy to sand. Use for fairing. Don't use for structural gluing.

Unfilled epoxy penetrates end grain well, other grain not so well, and is pretty runny. Use to prime before gluing, and to saturate sheathing cloth. I don’t like to put on anything before applying fiberglass, but other people do it differently.

Thinner makes epoxy runny and weaker. I don’t see any application for thinned epoxy at all, with the possible exception of very specialized stuff like CPES. Don’t do it.

Mustard on ham sandwiches. The epoxy leaves a funny-tasting residue on your teeth.