Epoxy wet out totally clear?

[CCrew]

Help me out quick here guys.. please!<br /><br />Is epoxy as it builds out supposed to wet out and remain totally clear? On the first two mat layers it is, almost perfectly, but by the time I get to about the third layer of 17oz biaxial, it's more like an amber translucent rather than totally clear. Keep in mind that I'm using a 17oz biaxial with 3/4oz mat stitched to it, so it's basically 2 layers of 1 1/2 oz, then a layer of 3/4, then a layer of 17oz, then another layer of 3/4, then another layer of 17oz, then 3/4 again, 17oz again, then two layers of 1 1/2 oz to cap it off. I.m just concerned that it doesn't seem to stay clear, although each layer seems to totally wet out properly. <br /><br />Thanks!<br />Roger

 

[airman]

Re: Epoxy wet out totally clear?

Sounds pretty close tp my experience with epoxy. I wouldn't worry.

 

[CCrew]

Re: Epoxy wet out totally clear?

Thanks airman.<br /><br />I was just a tad worried, looks like I'll have a decent investment in epoxy alone, not including cloth just getting these in. Looks like it's going to take 4-5 gallons of epoxy just to get the stringers in. Wanted to make sure that it's right the first time. I'd seen it with polyester, it's my first time with epoxy and the epoxy so far had seemed pretty clear, but I'm going for thickness now and this one made me scratch my head.<br /><br />Thanks again!<br /><br />-Roger

 

[G DANE]

Re: Epoxy wet out totally clear?

How manny layer did you mention CC - 10 - are you building a tank !!

 

[usedboats4u]

Re: Epoxy wet out totally clear?

epoxy's will not desolve the binding agent in the mat, this will case a clouding effect with no ill effects.

 

[CCrew]

Re: Epoxy wet out totally clear?

"epoxy's will not desolve the binding agent in the mat, this will case a clouding effect with no ill effects"<br /><br />I'm using stitched epoxy mat. Even though stitched, does it still contain a binding agent?<br /><br />GDANE, No, not a tank, if I was I'd be using Kevlar! Just want to make sure that this thing is as solid as a rock. I've always been a big proponent of "overbuiling" and I'll be darned if I ever want to do this again! It's not all 10 layers, as I used progressively wider pieces to get overlap, but the way I did the ovelap on the hull to stringer filet, it's actually closer to 14 layers at that spot!<br /><br />-Roger

 

[kenneths]

Re: Epoxy wet out totally clear?

CC, it's normal for epoxy to "yellow".....no prob there.........

 

[Hooty]

Re: Epoxy wet out totally clear?

14 layers is way to much. If you put that much mass next to the hull, all at one time, it'll cause a large shrinkage mark on the opposite side. If you can feel the exotherm, of the laminate, with your fingers, it's to thick.<br /><br />c/6<br />Hooty

 

[CCrew]

Re: Epoxy wet out totally clear?

"If you can feel the exotherm, of the laminate, with your fingers, it's to thick"<br /><br />Can't feel the heat, and no marks in the hull. Total laminate thickness is about a heavy 1/4"-3/8" at the filet and tapers out 6" up the stringer side and out the hull to basically 1 layer of mat. So far it seems to be working well..<br /><br />Are you saying too much simply because of the exotherm, or is there a structural reason why?<br /><br />Thanks!<br /><br />Roger

 

[Hooty]

Re: Epoxy wet out totally clear?

Exotherm and thickness. A laminate shrinks the most in it smallest dimension (thickness). Even though the polyester is not a thermoplastic, heat will "soften" it somewhat, so, with a thick laminate and higher exotherm(the greater the mass, the faster the gel and higher the exotherm)you're running the risk of shrinkage or "show through". If you're doing the work where it's cool and using the epoxy with the long gel time, you may be ok. <br /><br />c/6<br />Hooty

 

[CCrew]

Re: Epoxy wet out totally clear?

"If you're doing the work where it's cool and using the epoxy with the long gel time, you may be ok"<br /><br />Thanks for the clarification Hooty, I appreciate it. I'm using US Composites epoxy with a "medium" hardener, and seeing about a 30 minute pot life at 70 degrees (heated garage). It's taking about 3-4 hours to go to a good gel, about 8 hours to a non-tacky cure, and I'm really not seeing it get good and hard for 24 hours. If I sand it at 24 hours it's obvious that it still has some cure time left to it. After 72 it's like steel. If I bump the garage to 80 degrees those times shorten considerably. Hopefully that's why I'm not seeing what you've described. <br /><br />-Regards, and thanks again!<br />Roger

 

[18rabbit]

Re: Epoxy wet out totally clear?

You probably already know this, and it may not apply to what you are doing, but if you get to a point where you need to put on epoxy that will be sanded to blend smoothly into a existing epoxy surface, you want to do the initial sanding just around that 24-hour period where “it's obvious that it still has some cure time left to it”. The new epoxy responds to the abrasive (3M Roloc Scotch-Brite disc) with negligible effect on the fully cured epoxy. Prevents ripples and gouges in a smooth surface. Perfect blending.

 

[crab bait]

Re: Epoxy wet out totally clear?

that's great that your trying to do a good job... where in these times 'slap & go' is the norm...<br /><br />what's done is done,, an is probably ok.. but in some instantances,, more is not better... i think it's to thick,,offhand.. can't put into words why,, except to say it may be brittle...<br /><br />also,, thick applacations of epoxy is bad..<br /><br />apply wet glass,,, SQUEEGE OFF excess,,, apply next layer...or do a couple layers an then squeege off the excess... <br /><br />but a thick epoxy wetted job is bad...<br />it's like the fibers aren't doin' their job..cause it's epoxy choked..<br /><br />also,,, i never heard of 'epoxy mat'.. not sayin' there ain't,, tho... epoxy has it's own cloths ,, an 'mat' ain't in the family... that i know...<br />also,,

 

[Hooty]

Re: Epoxy wet out totally clear?

Last item on the page.<br /><br /> Epoxy Mat <br /><br />c/6<br />Hooty

 

[CCrew]

Re: Epoxy wet out totally clear?

Hooty, that's exactly the mat. The cloth is here.. this is also a stitched mat backing.,..<br /><br /> First item on the page.. <br /><br />Roger

 

[Hooty]

Re: Epoxy wet out totally clear?

Yeah, I've used that to. Check out the Knit Bi-axial Style 1815. It's next-to-last item on this page. I'm likin' it a lot.<br /><br /> Fiber Glast <br /><br />c/6<br />Hooty

 

[crab bait]

Re: Epoxy wet out totally clear?

well ,well,, whatayaknow,, there is an epoxy mat...!! thanks HOOTY...<br /><br />just an FYI,,fellas.. <br /><br />only use epoxy grade fiberglass materials with epoxy products,, only... don't really no why,,, just know DON'T...<br /><br />since most fiberglass is polyester grade,, an you can't tell them apart be eye.... be careful what ya buy & use... <br /><br />tip::<br /><br />if'n you have both on hand in your shop an there're outta the bag... ( all looks the same ) take a maker an write a E right on the material...or P for the other...<br /><br />another tip.. <br /><br />regular ole' vinegar cleans off uncured epoxy like nuthin' else...an ofcoarse ,it's cheap ... but utmost,, it's safe..

 

[BillP]

Re: Epoxy wet out totally clear?

CCrew, There are various reasons for the epoxy to get cloudy and none to worry about under normal conditions. I've seen it happen for years with all types of cloths/mats and never a problem. Yes, I think you are overbuilt but no harm done. Bulk is your friend if you can handle the extra weight. Epoxy is also very flexible in comparison to poly res and can handle a wet layup way better than poly. Tapering helped too.<br /><br />I respectively disagree with Hooty on the heating/shrinking "problem". Polyester or epoxy...most fiberglass production hulls made get "warm to the touch" during construction and it presents zero problems during construction or years later. "Warm to touch" laminating is just not an issue in the boat mfg industry. Print throughs and structural problems while doing stringers on existing hulls are a long shot at best, even when done "hot to the touch". Heat is more of a problem on new hulls with "green" gelcoat with a layer of thin "green" surfacing mat. Hot (read really hot to touch)laminates can create air pockets that make visible bulges but this is an extreme case and you may even see smoke.

 

[Realgun]

Re: Epoxy wet out totally clear?

CCrew the wood is going to fail before the epoxy and matting you did. I am going to use 2 layers of 6 oz S-Glass made for surfboards. Now surfboards are foam core so you know they are not that strong but the epoxy and glass make it real strong. Think of it as driveway made of cement. The cement is very strong in compression but not in tension. Thats why they put steel mesh in concrete. This is the same with epoxy reinforced fabric.

 

[BillP]

Re: Epoxy wet out totally clear?

Foam surfboard blanks are cut in half (or more pieces)lengthwise and wood stringers are glued in. That's the prime strength of the surfboard. Even glue lines without wood make a big strength increase. Foam strength is adjusted by changing the density, which is done by how much volume is poured into the mold. Expansion is done under pressure so more mix means higher density. Higher density mainly gives more protection from "denting" and dinging. Glassing helps but is primarily done to keep water out of the foam.