View Full Version : Epoxy Consumption

05-28-2002, 06:33 AM
Hey guys,

I've begun sheathing the hull. I planned on using one layer of 4 oz xynole and one layer of 4 oz dynel. I've noticed so far that a "6 pump" (med. pumps) batch of epoxy yields only about 2 sq. ft of coverage. Is this normal?

Thanks in advance.


Wayne Jeffers
05-28-2002, 08:58 AM

I've always used graduated cups and (now) scales for measuring epoxy, and used glass cloth in the 6 to 7.5 oz. range, so I have no experience with pumps or lightweight fabric. Assuming even half an ounce per pump stroke, it seems to me you should be getting much greater coverage with lightweight fabric.

Remember, you should be using a low-viscosity (watery) epoxy for sheathing. It will saturate the fabric easier than a thick formulation and go further, too.


05-28-2002, 10:22 AM
Thanks Wayne.

I'm using unthickened WEST epoxy. It seems awfully watery.


05-28-2002, 05:37 PM
Iv,e been doing a little epoxying myself lately. I used sys 3. with 6 oz. fiberglass. I also used cups instead of pumps, though I'm quite familiar with west. As far as coverage, someone suggested using a rubber squeegee to spread it. It worked great. The stuff went a lot farther than I thought. I don't really know the exact square footage but I was definately pleased with the coverage. Another thing I learned(the hard way) is be exact with the measurements and mix,mix,mix.

Wild Wassa
05-28-2002, 07:08 PM
Beowolf, Caster of lead. What volume are you mixing? This will give a good indication as to whether your usage is light, heavy or overly heavy. Do you feel it's overly heavy? Do you have data sheets with coverage figures? Or is it the repetition of mixing that's giving you the irrits?

Are you sheathing over a wet or dry base? Is the base smooth? The squeegee is a great idea. Don't squeegee so firmly so that there is nothing left between the interfaces of cloth and base though, in an attempt to gain greater coverage. Damaging the cloth is easy. Epoxy usage is very heavy when sheathing. This is not just a surfacing process, it's a building (up) process with a greater thickness and a greater volume of epoxy than we expect.

[ 05-28-2002, 08:52 PM: Message edited by: Wild Wassa ]

05-28-2002, 09:10 PM
I have usually figured that my epoxy usage, with waste,will be about 120% of the weight of the cloth. For example, if using 9 0z. cloth (1 0z. per square foot) I would expect to use a little more than an ounce of resin per square foot. This assumes that the surface you're putting the cloth on is fairly smooth and that you're using a squeegee. This amount will wet out the cloth, but not fill the weave- for that you'll need a second coat that will apply at the rate of about 1 ounce per square foot, maybe a little less for lighter cloths.

For fun, most epoxies weigh about 9 pounds per gallon, although this varies with brand and type, so a gallon with waste will coat about 125 square feet, or saturate 110 square feet of 7.5 oz. cloth, or 30 square feet of 24 oz. roving. The kicker is you can easily get only half this coverage by not using the proper viscosity, or being lax with your squeegee technique. Warmed, thin epoxy will give you the best economy, but you've got to work fast!

05-28-2002, 09:13 PM
Forget the pumps when your wetting out any kind of area. It's a lot quicker to get a mix of 20 ounces resin and 4 ounces hardener using a graduated quart mixing pail. I've gotten them from Jamestown for cheap enough. You can fill several pails with resin and add hardener to one pail, use it up and then add hardener to another pail,etc. This really keeps the pace going quickly.

Tom Lathrop
05-28-2002, 10:31 PM

To try to give you some kind of answer we would need to know how much epoxy you are talking about in weight or volume. I can give you an example of my own epoxy usage on Xynole and you can compare to that.

first coat (dry method) = approx. 4oz/sq ft
second coat = approx. 3.3oz/sq ft
third coat = approx. 2.8oz/sq ft
total is about 9 3/4oz per sq ft

Dynel should be about the same, I think. Data on glass cloth is of no use for these fabrics since their properties are so different.

I have to ask why you are using both Xynole and Dynel together? A single layer of Xynole is adequate for most non structural sheaths and neither of these fabrics add any strength to the boat. I consider Xynole superior in every way to Dynel as a sheath reinforcement.

05-29-2002, 09:37 AM
Thanks guys,

JMAC - I'll pick up some containers and go that route. Sounds a whole lot better than what I'm doing.

Tom - Thanks for the input. I picked up the Dynel as a "topcoat" based on the recommendations on the defender site. I'll be curious to see what it looks like after the 2nd or 3rd coats on the xynole.

More to come later.


Ross Faneuf
05-29-2002, 01:06 PM
For wetting out I've always used a 35 oz or 1 qt paint cup, and as much epoxy as I can stir in it. Usually use pumps because it's quick enough. On Ceol Mor, a large piece of Dynel (5'x16') would take 4-5. There's a reason I've used nearly 2 tons of epoxy on the boat.

Application: I'd just pour the whole thing on (boat upside down) and spread with a 4" multi-use spreader. I like to squeegee it down well - soaked but not floating. Don't wear new clothes. In fact, I always pour, spread, and squeegee when applying any kind of cloth.

[ 05-29-2002, 02:09 PM: Message edited by: Ross Faneuf ]

Wild Wassa
05-29-2002, 02:20 PM
Pumps keep the solutions clean. Pump more often.

Conrads, after fairing the waistage is impressive. In fact shocking. It's great to have a few figures confirmed.

Thanks Skippers.


ps, Ross, amazing. I thought pouring poly on foils was a big deal. 2 tons. The guys I work for have a 'big boat' (16 berth). They don't trust me yet, to even look at her.

[ 05-29-2002, 05:28 PM: Message edited by: Wild Wassa ]