Ah Crap, I used EzPoxy-84 on my strakes!!! Now what?

[rnbraud]

Hello all,

 

Need some advice; as usual.

 

I am working on my strakes. I have the skins and the ribs all done and the ribs installed on both sides.

 

I used Ez-Poxy resin with the slow hardner, E-Z 84, for the strakes. I have been using MGS for everything else.

I chose Ex-Poxy cause it has been mentioned it is the best for fuel resistence.

 

I just finished taping in the bottom skin on the left side to the ribs. Next up is the right side bottom skin.

 

I now read a posting where Dave Wilenius mentions this:

 

>Note also that Ez-Poxy hardners 83 & 84 are also on the cycloaliphatic amine

>list. Only Ez-Poxy 87 (the slow Ez-Poxy hardner) is in Gary's aromatic amine

>list.

 

Ah crap!!! From Gary Hunters presentation I read that Ez-83 was the fast hardner, Ez-84 was the slow hardner, and Ez-87 was the really slow hardner.

I thought I read from other postings that the best choice for the strakes was the Slow hardner. I realize now it is the slowest hardner that is recommended.

 

So I go to the Aircraft spruce website to see about the Ez-87 hardner and I note the following on there webpage. Note "Aromatic" in all three hardners:

 

 

> E-Z POXY TECHNICAL DATA

> E-Z POXY RESIN SYSTEMS FROM COMPOSITE POLYMER DESIGN

> E-Z 10 Epoxy Resin

> E-Z 84 Aromatic Amine Hardener

> E-Z 83 Aromatic Amine Hardener

> E-Z 87 Aromatic Amin Hardener

 

 

Now I am really confused, so I go and check the archives and I find this tidbit from Gary Hunter himself:

>Safe-T-Poxy I or now EZ-Poxy 87 is probably by far the best in this

>category, with or without a post cure. Chemical resistance is one of the

>prime attributes of epoxies beyond homebuilding airplanes. They are used

>for building fiberglass chemical storage tanks and piping and for lining of

>steel tanks to prevent corrosion. In that industry the curing agent "type"

>governs the degree of chemical resistance. Aromatic amines are by far the

>best know curing agent type for overall chemical resistance - particularly

>in fuels, solvents and strong acids. EZ-Poxy 87 is the only aromatic amine curing agent available to the homebuilt world.

Crap, crap, crap, I used EZ-Poxy 84!!!!!!!!!!!!!!!!!!!!!!!!!

 

Ok, now for the advice.

 

If I get some Ez-87 hardner would it do any good to coat my strakes with two layers of pure epoxy with the 87 hardner and cover with peel-ply between coats?

 

Is two thin coats going to provide me with any protection or am I just screwed cause I used the 84 hardner?

 

If no to the thin coats, should I layup another ply of glass with the Ez 87?

That would make my strakes pretty heavy, but should provice protection.

 

I really don't want to re-build my strakes nor use some form of sealant line Jeffco or Pro-Seal.

 

What is the advice from the group.

 

Any and all comments or suggestions are welcome.

 

Later.

 

P.S. No, D and Tam I don't want to use Jeffco!!!

 

Rock N. Braud, II

Sr. Software Engineer, til April 15!!!

Sevis Systems, Inc

Cozy Builder - Chap. 21

[Stinky]

I think you will be okay. In one of his articles, maybe the same one you quote, Gary says that 84 is okay if postcured. Quoting the article, there are many ways to get the temperature up to 140 degrees F for seversl hours and that should be sufficient.

 

To wit, "There are many ways to obtain a post cure on the tank. Before the tops are put on, you can use heat lamps to cure the inside surfaces. You can pre-post cure the inside surface of the top too. After the top is bonded in place you can post cure these bonds by heating the exterior surface with heat lamps. The heat will work its way to the bonds. OR, after the top of the tank is bonded on, you can circulate warm air through the tank for several hours. I did this with the outlet end of my vacuum cleaner inserted in to the fuel cap opening. About 140F is sufficient. RULE OF THUMB - If you can hold your hand on the surface to the count of 10 - the temperature is 140F or below. " --Gary Hunter

 

 

Carl

[Kent Ashton]

My Cozy IV has been flying since 2002 with Ez-poxy strakes, no formal post-cure. I do not recall ever using the very slow hardener so I probably used what is equivalent to the 84 hardener. Today, I'm using 84 hardener on my LEZ project. I figure that if you stick to avgas, you'll be fine. If gas formulations change radically and my tanks start to deteriorate, I'd rebuild the strakes with a suitable epoxy and/or liner.

 

The Harris's (EZ Hangar) rebuilt a lot of bad parts, like leaking or crooked strakes. They would saw away the old strake, gently sand off the overlaps, rebuild and refinish. It probably takes them no more than a couple of weeks to get an EZ back in the air.

[Big Steve]

Rock:

 

 

 

 

I think You are allright with the 84 hardener. You could scuff it up and paint on a couple of layers of 87 hardened stuff but I think you would be adding unnecessary weight. I have had a couple of pieces of glass in a bottle of auto gas for almost 2 years now I can see no change. I took it out about 6 months ago. It acted just like a regular piece of fiberglass. I am using 84 resin on the whole plane. STeve

[Lynn Erickson]

Rock:

 

 

 

 

I think You are allright with the 84 hardener. You could scuff it up and paint on a couple of layers of 87 hardened stuff but I think you would be adding unnecessary weight. I have had a couple of pieces of glass in a bottle of auto gas for almost 2 years now I can see no change. I took it out about 6 months ago. It acted just like a regular piece of fiberglass. I am using 84 resin on the whole plane. STeve

Do you have the sample submerged or some above the liquid. in most cases it is the vapors that do the dissolving and have the most effect. also the vapors have more effect when heated like when the sun is heating the strake. it is also hard to know if the fuel has alcohol in it. the pump gas may or may not. it only says it may contain alcohol. how do you know that the sample you have does?

[Stinky]

... the pump gas may or may not. it only says it may contain alcohol. how do you know that the sample you have does?

I do not mean to hijack the thread into something else and will move this if need be. However this is an interesting question that deserves some thought. I read of a test that one could perform. This was back in 95-97 time-frame, so my memory is not complete but I seem to remember that one could place the gasoline in a glass jar and mark the side of the jar with a sharpie. Then add a small amount of water (maybe half the volume of the gasoline?) Cover the jar tightly and shake vigorously. Then let sit.

 

Any alcohol in the gasoline was supposed to dissolve in the water and the gasoline / water line would shift if alcohol was present.

 

 

Carl

[brainfart]

> it is also hard to know if the fuel has alcohol in it. the pump gas may or may not.

> it only says it may contain alcohol. how do you know that the sample you have does?

 

If in doubt, add some alcohol intentionally.

[haiqu]

 

If in doubt, add some alcohol intentionally.

 

I'll drink to that!

 

Rob