Epoxy

[5-A]

What brand do you use?
How much do you pay for the epoxy you are using?
Where do you buy?

[blueskyracer]

I use West System epoxy. I buy it by the gallon with a quart of hardner for about $140 from the local marina in Missoula but you can also buy it on line from Jamestown distributors.

Hope this is what you were looking for.

[Fast Jack]

sticky situiation

Your best bet locally is Hamilton Marine in Portland --for West systems or Mass epoxy, both are good products.

[Bill Huson]

West . . .

and I must bend over and drop trou when I buy it because my only local source is Waste Marine. Buy it by the gallon now. For my next boat I will search for best price on a 45lb/5 Gal set.

[Dave M]

West System

If you want the best, get West. It is also the most expensive. If you need a few gallons, itis cheaper to buy by the 5 gallon package. Run you between $400 - $500 depending on your source.

Remember, if you get any epoxy shipped, you pay shipping plus the hazzardous materials fees.

Lots of other epoxies work too, and are cheaper. Mas I see works good, and a few others. Just make sure you are getting Epoxy resin, and not a vinylester or polyester resin. These are best used in fiberglass and Carbon/kevlar applications.

[blueskyracer]

Remember, if you get any epoxy shipped, you pay shipping plus the hazzardous materials fees.


I think that the haz fee and shipping is figured in the store price also because unless you are buying directly from West system the store had to have it shipped also.

[ZUL8TR]

epoxy source

I have tried several expensive brands like MAS, West but have had just as good performance with a more economical brand from Clark Craft.

http://www.clarkcraft.com/cgi-suppli...431dec36e89ec5

The price is reasonable and I prefer the 1:1 mix as easy to do without pumps. The shipping is also reasonable. The shelf life is long and no amine blush and can apply coats after initial tack without sanding for quick mil build up and dries crystal clear and is a bit more flexible than MAS or West. The tests I have done yield a very strong joint with good penetration. I adjust the thickness with cabisil (silica powder) when needed.

Clark Craft also has a glue that is more convienent than the epoxy with cabisil filler

http://www.clarkcraft.com/cgi-suppli...431dec36e89ec5

[Dave M]

Ratios

Remember, the ratio determines the strength of your joint. 1:1 is not as strong as a 5:1. It may very well be adequate in your application. Just be sure to compare it to the figures West System puts out regarding Tensil Strength, Felxural strength, etc. It is also interesting that the slow cure epoxy yields more strength than the fast hardner... because the mix ratio is different.

I imagine West System in the slow cure ratio is way more than we need in race boats. Typically you never see joint failure on boats, the wood gives out long before the epoxy does when it comes to testing the strength of a boat both on and off the race course.

If you are on the east coast, try Eastern Burlap trading company, they have West at a reasonable price as well. The shipping costs quoted you will likley include hazz mat fees if applicable. Very fast ship time to me in the past.

[ZUL8TR]

epoxy ratios

Remember, the ratio determines the strength of your joint. 1:1 is not as strong as a 5:1. It may very well be adequate in your application. Just be sure to compare it to the figures West System puts out regarding Tensil Strength, Felxural strength, etc. It is also interesting that the slow cure epoxy yields more strength than the fast hardner... because the mix ratio is different.

I imagine West System in the slow cure ratio is way more than we need in race boats. Typically you never see joint failure on boats, the wood gives out long before the epoxy does when it comes to testing the strength of a boat both on and off the race course.

If you are on the east coast, try Eastern Burlap trading company, they have West at a reasonable price as well. The shipping costs quoted you will likley include hazz mat fees if applicable. Very fast ship time to me in the past.

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All the testing done with different epoxies and mix ratios when I was engineering at a marine research lab and work that I reviewed by others indicates that for wood and plywood bonding, air dried 2 part epoxy strength is not significanly related to the mix ratio and all plywoods tested where not as strong as the epoxy bond joint. Failure always occured as plywood shear or delamination rather than the epoxy joint giving way. The final cured properties of the epoxy are related to the design chemistry of the product and the mix ratio is made compatable to this design. The proper chemical cross linking that occurs during the curing process is created by the designed chemistry of the product and mix ratio.

A point often overlooked is that mix ratios need to be accuratly measured by either volume or weight per manufactures instructions and it is a lot easier to maintain mix accuracy at 1:1 then at 1:2, 1:3, etc. The usual requirement is a deviation of +/- 2% is acceptable to maintain the properties designed into the product. Here is a discussion on mix ratio accuracy.

http://www.epoxyproducts.com/mixratio.html

I have succesfully used epoxy for years on plywood construction for many different applications such as boats, structural timber, marine water tanks, salt water flumes, pump sumps, etc and the mix ratio vs strength never was a strength issue. I personally use the 1:1 because it has less chance of mix error and offeres a bond much stronger than the plywood or wood used.

As a footnote my first high school race boat was a Scat Cat Popular Mechanics hydro that was constructed with Weldwood water mix glue. The boat lasted for years with much use and never a failed joint. I believe the better joinery required for the Weldwood glue was a big issue here where as when using epoxy joinery can be a little less careful and still get a good strong joint.

[Blackhawkguy]

Every marine repair or store

Any marine repair or store should have a distributor that handles west system, there usualy is a haz-mat charge but if they buy enough and get free shipping then that charge is eaten by the distributor. Try and find one that will work with you on the price, maybe a sticker on your boat, as stated there are several other brands, if you want west system then you should have no problem finding a sourse, it is very widely used in the marine industry.

Kerry

Also note the pumps for the west are 1:1, they measure the amount for you, one pump hardner to one pump base-very simple to use

[krazy karl]

I use an epoxy by the brand name Aero-Marine. It is sold by JR Greer in San Diego, can be found on line. Reasonable prices and fast shipping which is included in the price. It is a 2 to 1 mix and I think it is comparable to West System.
kk

[Dave M]

Whatever Works

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All the testing done with different epoxies and mix ratios when I was engineering at a marine research lab and work that I reviewed by others indicates that for wood and plywood bonding, air dried 2 part epoxy strength is not significanly related to the mix ratio and all plywoods tested where not as strong as the epoxy bond joint. Failure always occured as plywood shear or delamination rather than the epoxy joint giving way. The final cured properties of the epoxy are related to the design chemistry of the product and the mix ratio is made compatable to this design. The proper chemical cross linking that occurs during the curing process is created by the designed chemistry of the product and mix ratio.

A point often overlooked is that mix ratios need to be accuratly measured by either volume or weight per manufactures instructions and it is a lot easier to maintain mix accuracy at 1:1 then at 1:2, 1:3, etc. The usual requirement is a deviation of +/- 2% is acceptable to maintain the properties designed into the product. Here is a discussion on mix ratio accuracy.

http://www.epoxyproducts.com/mixratio.html

I have succesfully used epoxy for years on plywood construction for many different applications such as boats, structural timber, marine water tanks, salt water flumes, pump sumps, etc and the mix ratio vs strength never was a strength issue. I personally use the 1:1 because it has less chance of mix error and offeres a bond much stronger than the plywood or wood used.

As a footnote my first high school race boat was a Scat Cat Popular Mechanics hydro that was constructed with Weldwood water mix glue. The boat lasted for years with much use and never a failed joint. I believe the better joinery required for the Weldwood glue was a big issue here where as when using epoxy joinery can be a little less careful and still get a good strong joint.

Good luck in your repairs/builds. Obviosuly it should be well built and strong. My notes came from the manufacturer.

[Smitty]

ZUL8TR, have you done any testing of resorcinol waterproof glues against the epoxies and urea formaldehyde Weldwood? I read that resorcinols obtained a bond that was chemical as well as mechanical. One possible drawback was that moisture content of the wood had to be controlled (IIRC, about 18% was desireable), and another is the color of the glue line (purple); I forget about the gap-filling qualities or lack of same. You point out that the wood tends to fail before any of these glue joints, properly applied; would that mean that the process offering the best penetration of the wood might hold up best, other things being equal?

[bill boyes]

I use System 3, Have for years as does Darrell Sorensen.
Not that anything is wrong with West. It is excellent. Just when I used West I had a lot of waste as the mix ratio is like 4 or 5 to 1. Just very hard to make a small batch of less than one ounce.
System 3 is in Auburn Washington. I use the the basic epoxy at a 2 to 1 mix. They have 3 hardeners Slow, Medium and Fast. For me where I live the temp varies from low 30s in winter to over 100 in summer as slow to to slow and fast is way to fast. The Medium works best for me at those temp ranges
I have been told that their T-88 is excellent. However, I broke down and bought a Sticky Stuff pump and it is set up for 2 to 1. That pump has paid for itself many times over by reducing waste.
There has been many threads on this subject in the past and there will be many who say that the product they use is the best. I prefer System 3 because I like it and know how to work with it so that is what I use.
Visit their web site. Has lots of info on epoxy.

[ZUL8TR]

epoxy vs other

ZUL8TR, have you done any testing of resorcinol waterproof glues against the epoxies and urea formaldehyde Weldwood? I read that resorcinols obtained a bond that was chemical as well as mechanical. One possible drawback was that moisture content of the wood had to be controlled (IIRC, about 18% was desireable), and another is the color of the glue line (purple); I forget about the gap-filling qualities or lack of same. You point out that the wood tends to fail before any of these glue joints, properly applied; would that mean that the process offering the best penetration of the wood might hold up best, other things being equal?

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Smitty during the time of the testing of epoxy at the marine facility no resorcinol or urea glues were used because of toxicity issues noted by the biologists for the marine containment facilities we were constructing. As far as the bond of resorcinols being mechanical that is true and that is a property also shared by urea and epoxy gluesl. Resourcinol glue is a 2 part chemical mix like epoxy and the urea glue (like Weldwood plastic resin) is a water based product and all have chemical reactions ot set the internal glue structure.

As far as the mechanical bond it is present and needed in all the glues discussed because at the micro level there are holes/irregularities in the wood that the glue penetrates that will provide a mechanical bond at the wood - glue line. Therefore glue penetration is important to the bond but as to the depth of penetration vs the strength of the bond I do not have any info. The epoxy is stronger by itself than resorcinol or urea glue. The latter two are very brittle by themselves when compared an equal thickness of epoxy therefore joint thickness matters with resorcinol and urea and a thin joint line is required. As I stated in a previous post above epoxy is a better filler and joinery can be not as accurate but this would not be an excuse to get too slopy with the joinery. I believe in good carpentry regardless of the glue used.

Here is a detailed article on quite a few glues with discussions of failures and pro and con:

http://www.cpadhesives.com/media/Cla...atAppendix.pdf

Near the end of the artical this author prefers the resorcinol as the most lasting and ability to take repeated stress fatigue if the dark glue color is not an issue. He note the failures of epoxy is typical marine environments. Note that most fresh water the race boats do not share the same environmental conditions discussed in the article where epoxy failed.