Epoxy 1:1, 2:1, 4:1?????

[longbow dave]

I'm getting ready to build my 1st boat, a 13' fishing kayak. This whole epoxy thing has kept me at bay way too long. The design is stich and glue. I will be using 1/4" Okoume 1088 plywood. I really do not want to encapsulate with epoxy or glass. I think I just want to cover the outside bottom with Xynole-polyester for abrasion resistance and paint the rest in and out. I live in the Tampa, FL area. Does anyone have a suggestion for epoxy resin for a 1st timer in this warm region? I've read way too many adds for these different resins (1:1, 2:1 and 4:1).

[JimD]

Welcome to the forum, longbow dave. Hard to beat RAKA (a 2:1 mix), which is a Florida company IIRC.

[JimConlin]

Particularly for a beginner with a small project, the 'mustard pumps' are a very good idea. 'One squirt each' is easy for simple folk like me to remember. Mosts systems have a 'slow' hardener. In Tampa, that'll probably be OK, if you stay out of the sun and are reasonably organized. Personally, I like the West System epoxys (#206 hardener for you).

[Gold Rock]

The specific mix ratios of the resin/hardner are not the relavent concern, as such. The variable of interest is the rate of activity of the hardner (catalyst). Catalysts are formulated to react quickly, slowly, or somewhere in between. This is significant depending on the ambient temperature of your work environment. Very cold temps, a faster rate of cure is desireable; warmer temps would benefit from a slower curing formula (giving you more time to work with the chemicals before they begin to set). The resin is the same, only the catalysts differ. One common manifestation of this difference is the ration of resin to catalyst.

[AstoriaDave]

Longbow, use the 2:1 resin; ratio is easy to measure out compared to the 4:1, and the 1:1 resins are not designed for water immersion. Where you are, I'd definitely get the slow hardener. Pick a brand you like; all are up to the task.

I am very puzzled why you resist priming the wood with epoxy. Adds little weight, and is a good base, once sanded, for many paints. Two rolled coats should do it. Okume is only moderately resistant to rot, so it should be protected. Paint will do it, but it is better to have an underlying layer of waterproof material so when the paint gets scratched (and, it will!), you have a backup. Depending on the size of the craft, I bet a quart of resin and a pint of hardener would do the whole job. Can't buy less than that amount and get a good price, these days, anyhow.

[RodB]

I live in Dallas and used over 20 gallons of System III... in over 95 degrees... I mostly used fast hardener when I could... about 50%-60% of the time.. . and medium hardener the other 25-35% of the time.. only used the slow hardener 15% of the time or less... for jobs that required plenty of time like applying the biaxial tape to bond the joints that ran the full length of my 18 foot skiff.

System III is very versatile in varying temps and humidity.... it is a 2:1 ratio...and quality product that is a good 20% less than West. The plastic pumps work great and you can check the amount you are throwing with each pump with a 1 ounce plastic measuring cup... then just pump and mix well... no problems..

If your going to encapsulate the boat... do it right... minimum of two coats of epoxy... on areas not exposed to the weather, sun, etc...and glass the exterior surfaces that will be exposed to the weather.. you won't be sorry...

Don't develop a phobia about working with epoxy...its a snap... just read the System Epoxy book and ask questions here...

Most here will be glad to offer up a step by step procedure to help you out.



Good luck.

RodB

[pipefitter]

I'm in Tampa as well. I built outdoors. With slow hardener, you have to calculate the afternoon thunder showers well in order to have time to cover the hull in case one blows up unexpectedly this time of year. The slow mix will use a window of about 6 hrs. The slow is best for application of glass and situations where you need some working time for lengthy glue joints. I recall many mornings looking at the cloud count moving east to see if they were backing up where I could see them before they returned full of water. Slow is good for glassing but still only really gives you about 20 mins of true wet out times.
I used US Composites because I knew some pros that used it in bulk quantities.

FGCI over in St. Pete have good products as well with knowledgeable staff to help with your questions and skill level and have all the tools and everything else you may need.

www.fgci.com

[Thorne]

Not all of the 1:1 epoxies are bad for use under water -- Smith & Co. make a nice one here in Richmond, CA. But you are probably smart to go for either the local brand or a large company's product like West Systems.

As above, the use of epoxy and glass cloth is very common for kayaks.

[Steve Lansdowne]

When in doubt, and to ease your mind when working, use a slower hardener when working than you may really need and wait a bit longer for it to set. A longer set time is handy when you realize after mixing it up that you've forgotten to do something that needs doing before you use the goop, and with a longer set time if you have a few extra odds and ends that need epoxy you can use any extra mixture to deal with these if the goop has not already started to set. Since goop is not cheap, it helps to make the most of what you mix. That said, mixing up more smaller batches will ease your mind and pocketbook if you find things take longer than you anticipated. Also, work in the evening when things are cooling down to avoid bubbles forming in your product from outgassing when coating new wood.

[George Roberts]

"I think I just want to cover the outside bottom with Xynole-polyester"

That is not going to stick to the epoxy very well - perhaps not at all.

Xynole is perhaps not the best choice, but ...

What type epoxy you use is a simple issue: First, it must not blush. Second, it must be thin enough to wet your cloth.

[WP Lyon]

I like the MAS Epoxy resins and hardener. Catalyst was mentioned in an earlier comment. The hardeners are not catalysts. I also like Dynel. I would recommend contacting Joel Mill at http://www.boatbuilder.org/

He has it all and responds to questions and emails in addition to processing orders quickly.

[Frank Wentzel]

Fiberglass Coating is St. Pete ( http://www.fgci.com/ ) makes many ratios. I believe their 3-1 is rated as most chemical resistant. I tend to use that or the 2-1 resin. They are close enough that you can get over and talk to them face-to-face - might help with your misgivings.

I strongly advise against polyester resin on wood. I was able to peal my whole fiberglass deck off the boat due to resin delamination. I know others have said that they have been successful with poly & wood but I wouldn't take the chance for a relatively small savings. Polyester also kicks faster (bad in Florida) and the styrene resin stinks as well as not being very good for your lungs.

It is easier to accurately measure resins closer to a 1-1 ratio. On a 5-1 resin you have to be very careful with the hardener volume since it is so much smaller than the resin volume.

/// Frank ///

[WP Lyon]

You are right Frank. Polyesters are not good for adhesion or resisting permeation which leads to failure by means of delamination. Hot tubs for awhile, years ago, were molded of polyester resins and glass. All failed quickly.

Vinyl esters as a group have much better adhesive qualities. I was almost tempted to use a product developed by Dow Chemical and now sold by Ashland Chemicals called Derakane 8084. Sticks like crazy and has good flexibility. I am happy with the MAS resins though their price is higher.

[John Meachen]

Are there any local builders using epoxy laminating resins who might provide advice?If you can learn of a resin that works in your location,buy some.I strongly recommend buying a set of small digital scales for accurate measurement of the components of the resin system,regardless of the mix ratio.

[Thorne]

George - why would you think that Xynole wouldn't work with epoxy?

http://www.defender.com/product.jsp?path=-1%7C10918%7C16458%7C309346&id=16176




Xynole Polyester lexible Fabric
60" wide
Sold by the yard

Item #: 751425 Manufacturer: SOUTHERN INDUSTRIAL Model #: 6044 1-25YD Shipping Weight: 0.30 Lbs. Our Price: Quantity: 1 to 25 $10.99 each Quantity: 26 to 99 $9.89 each Quantity: 100 and up $9.67 each



Description
Polyester fabric, similar to other non allergenic fabrics, for laminating with epoxy and polyesters over cold molded wood, fiberglass and foam.
Ideal for compound curves and corners, as it is soft, pliable and easily "wets out".
Widely used on canoes, surf boards, large boat decks, etc.
Higher tear strength than fiberglass, and has some elasticity for movement, especially on planked boats.
Perfect for waterproofing and reinforcing. Wgt 4oz. /Sq. Yd. , High chemical resistance, made in the USA.
Width - 60. Limited supply.

[RodB]

xynole will offer you a great protective sheath...but will be heavier than plain old 6 oz fiberglass cloth...

Xynole wets out fine with epoxy and offers several times more abrasion resistance...and more impact resistance than fiberglass.

Good luck,

RodB

[kengrome]

Not all of the 1:1 epoxies are bad for use under water ...That's for sure. We have this excellent 1:1 epoxy that was formulated specifically for plywood / fiberglass composite boat construction by the U.S. military while they were here in the Philippines. It's still being produced by the original military supplier because it seems to have 'caught on' with the locals before our military left the country, and it's still only $27 a gallon. It's no blush too, and it gives us plenty of working time even in this hot and humid climate. I wish I could export it, but ...

[longbow dave]

Thank you all for your quick response. It's time for me to "get off the dime" and build a boat.

[George Roberts]

"George - why would you think that Xynole wouldn't work with epoxy?"

I may have misunderstood. I thought the use was with polyester resin. It appears others thought so also.

---

In any case pound for pound zynole with epoxy costs more and has worse physical properties than glass with epoxy. The difference of opinions stems from the fact that zynole has a different density and different weave. Most people compare equal weights of cloth rather than equal finished weights or equal costs. This leads to very silly claims.