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View Full Version : Looking for good, economical epoxy/fillet product, and supplier



douge
10-19-2010, 09:29 AM
I'm building my first boat (18ft skiff) and have been basically learning as I go. I've screwed up in several places, but so far, I'm the only one that can pick out the problem spots. One thing I've noticed is that I've spent way more on materials than I had ever expected. I've been getting most of my supplies from http://www.jgreer.com/ and have been satisfied with their service. I've also picked up a few things from Jamestown Dist., Glen-L, and once from West Marine when I was in a pinch on a Sat. afternoon.

For epoxy, I've been using the J-Greer 300/21 system which goes for ~$140 for 3 gallons. For an epoxy adhesive, I've been using their J-Greer 300/11 system that goes for ~$46/gallon.

For fillets, I've been using Cabosil ($18/gallon bag) mixed with the 300/11 adhesive epoxy. I've tried using the 300/21 regular epoxy, but it just won't get thick enough. When you think it's thick enough, it just falls flat on you. I selected cabosil primarily because it seemed to give me the most volume for the price.

I'm too the point in my project where I need to do a bunch of fillets, taping, etc., and I think I'm going to go broke buying all this 300/11 + cabosil.

Q1) Is this a decent price?

Q2) Should I be using something else for my fillets?

Just curious what you serious boat builders do short of buying it in 55 gallon barrels.

Any suggestions on materials, brands, suppliers, etc. would be great.

Thanks again,

Doug

JimD
10-19-2010, 10:15 AM
Depends on where you are and what's available, but like many things, the price of fumed silica drops dramatically the bigger volume purchase you make. Don't remember what I paid for it but last time I bought some a couple years ago, came in a green garbage bag about half full.

kc8pql
10-19-2010, 11:24 AM
I get good mail order service from these guys. http://www.fgci.com/

Fumed Silica-
22 lb. bag - $164.29
5 lb. box - $59.32
5 qt. tub - $17.87

JimConlin
10-19-2010, 12:03 PM
Of those who'll admit to using epoxy, we have long and inconclusive arguments about which epoxy system we like, but most of us do just fine with one resin and two hardeners. The prices you're paying are typical for the un-branded products.
A filleting putty of epoxy and colloidal silica (aka Cabosil) is strong, very hard to sand, uses a lot of resin and is therefore heavy.
For fairing and larger fillets, most folks use either phenolic microballoons or quartz microspheres. A little cabosil will make a bubble putty spread more smoothly. A putty of epoxy and bubbles is weaker, softer, easier to sand, lighter and uses less epoxy.

When bought in realistic quantity, microspheres and cabosil are not expensive. A 5-gallon pail of either is about $40. I've bought it from Merton's (http://www.mertons.com/Additives/bubbles.html). The price drops further in larger quantity.

douge
10-19-2010, 02:30 PM
Thanks for the responses. Looks like I've been paying the going rate. I just ordered up a new round of supplies. Trying out the micro-balloons, 1/32" milled fiber, more cabosil, ... and of course more epoxy.

floatingkiwi
10-19-2010, 04:21 PM
Using wood dust from the sander, not saw, or good old flour that one might bake with, saves me a LOT of money. I reckon once the epoxy encapslates all the particles in the matrix , it is not of major importance what is used as all it does it put pockets of air into it. Microballons are glass spheres that collapse on contact with sandpaper, thereby enabling one to sand it faster.
I combine flour and wood dust to create the desired colour of glue, which is often visible in the finish somewhere.

RodB
10-19-2010, 04:57 PM
For fillets you should be using a mixture of standard epoxy with equal amounts of fumed silica (Cabosil) and wood flour thickened to the consistency of peanut butter. The wood flour thickens without adding much weight and is pretty much the standard ingredients for most filleting operations. For standard glue ups of joints, epoxy thickened to an Elmer's glue consistency with only fumed silica (Cabosil) is the standard epoxy glue... its very strong. For filleting... equal parts of Cabosil and wood flour is pretty much the standard, I'm surprised you have not seen this somewhere. IT works like a champ and is very hard to beat.

You should get the System Three epoxy manual (you can download it online) and perhaps the newest edition of: "The Gougeon Brothers on Boat Construction"... both very worthwhile references for your library.

By the way, you can get some pretty good prices on Wood flour (4.50) and Cabosil direct from System Three... $11.00/5qt container. Their cost on their standard resin is $ $80/gallon. I didn't realize how damn expensive they have gotten... I have used so much of their product, I hate to change now....but I may start shopping for future projects. I have always heard RAKA is resonably priced.

Good luck,

RodB

floatingkiwi
10-19-2010, 05:02 PM
Depends on where you are and what's available, but like many things, the price of fumed silica drops dramatically the bigger volume purchase you make. Don't remember what I paid for it but last time I bought some a couple years ago, came in a green garbage bag about half full.

You probably got half of a big sack they sell for around 90 bucks, as someone wanted to split the cost. I have thought of doin this. How much did you pay? Around 50 bucks?
Tap Plastics sell huge sacks for 90ish. I cannot remember the volume or weight off hand but it is like a FULL garbage bag.

RodB
10-19-2010, 05:30 PM
Q1) Is this a decent price?

Q2) Should I be using something else for my fillets?

Just curious what you serious boat builders do short of buying it in 55 gallon barrels.

Any suggestions on materials, brands, suppliers, etc. would be great.

Thanks again,

Doug

As above, use wood flour and Cabosil for fillets. AS far as epoxies go... System Three is hard to beat for pure versatility in varying temperatures and humidity, etc... They have three hardeners and the mix is always 2:1 resin to hardener. The newer and more expensive products they sell are purely for convenience if you don't want to mix the epoxy for each and every purpose in boat building such as gluing, filleting, filling, etc. Their best deal is to buy 15 gallons of their general purpose resin for $895, which is reasonable if you need that much epoxy. I have also used West and MAS... all three work well and are not inexpensive. There are many on this forum who use other epoxies and thay can chime in with some first hand experience. I know I'd like to see someone drag the prices down from the main players... cause they sure are gettting out of control on pricing.

Good luck,

RodB

jimkeen
10-19-2010, 08:11 PM
I have had tremendous results with this product. Adding some micro balloons make the sanding go easier.

http://www.boatbuilder.org/mascart/index.htm

Tomcat
10-20-2010, 09:21 PM
The basic principle is the rule of mixtures. The end product has the qualities of the component parts in proportion to their inclusion.

Fillets aren't all created equal, but in most cases what is being approximated is the cross grain compressive strength of a piece of light wood. In other words, if there wasn't epoxy, you would glue to a stringer for similar strength, and you still may in certain cases.

Getting the strength you need requires adequate quality epoxy and fillers. If you push cheap resins they will fail, but in certain circumstances they are fine. There are both a long term and short term issues. Some resins will gain hardness over many months and be adequate in a year's time. Try to stress them a few hours after they have hardened, like a next day keel fold up, and they will fail. So if one's project is dragging on, that may be a good thing.

When it comes to getting that wood like strength, across grain, you could also use a boatbuilding foam. Any of these foams are pretty munch indentable with your finger nail. So that is a measure of where you might end up, though I normally will have a harder fillet than that.

So on the powders. I use a 3-1 bubbles to cabosil mix. The correct explanation of these mixes has not quite been given here. The end product is called syntactic foam. Which is foam made by mixing bubbles into a hardening resin. The resin isn't foamed with gas as with standard foam manufacture. Little glass or phenolic spheres are simply mixed in there. The harder these spheres, the harder the foam, as with epoxy. Cabosil is added to control slumping, that's it where fillets are concerned. The less Cab you can use the better, particularly if you are using a quality epoxy that is hard to start with. I use 3-1 bubbles to cab. But if the Fillet was in a keel and couldn't go anywhere, I would use less or no Cab. On a ceiling joint, I would use dryish 3-1.

Wood flour is very inefficient, but it is a good colour match. You could use it on an external fillet with a clear finish and it would look great. It is nice to use, but it saturates with epoxy, and becomes almost solid, no foam effect, and very poor volume, you will be using about 3 times the epoxy, and you will spend a lot of time mixing and there is a weight penalty.

The fiber, milled glass, cotton, or Kevlar pulp, are good where tensile strength is concerned, but in reality, a glass cloth strip over a standard fillet is nearly always better, I have the same bags and tubes of these products in my shop that I purchased thrity years ago. Occasionally I use a bit of these products. They are inefficient like wood flour.

NealmCarter
10-22-2010, 01:36 AM
I`ll add my 2 cents...Do Not Laugh.. Sherman Williams...Did`nt know they had a Marine Division..Now you do...

wdbeyer
10-22-2010, 06:50 AM
Sherwin Williams is test marketing epoxy in some areas. Here in Winston-Salem, NC we just bought their bar-top epoxy for a job we're doing today.

RodB
10-22-2010, 11:11 AM
So on the powders. I use a 3-1 bubbles to cabosil mix. The correct explanation of these mixes has not quite been given here. The end product is called syntactic foam. Which is foam made by mixing bubbles into a hardening resin. The resin isn't foamed with gas as with standard foam manufacture. Little glass or phenolic spheres are simply mixed in there. The harder these spheres, the harder the foam, as with epoxy. Cabosil is added to control slumping, that's it where fillets are concerned. The less Cab you can use the better, particularly if you are using a quality epoxy that is hard to start with. I use 3-1 bubbles to cab. But if the Fillet was in a keel and couldn't go anywhere, I would use less or no Cab. On a ceiling joint, I would use dryish 3-1.

Tomcat...

Please elaborate... why do 90% plus designers recommend fillets formed with wood flour? Please elaborate on the strength of the foam (microspheres) fillets compared to silica and wood flour in proper diameter fillets... Naturally most here are interested in keeping up with cutting edge technoloby

Thanks

RodB