Basic fiberglass question.

[AltheaToldMe]

So, as I contemplate beginning my hull repair and waiting for the rain to stop so I can get started, I am experimenting with mixing resin and applying it to test pieces of glass. I?m not sure what I am looking at, so I figured I would ask.

Basically, I have laid out two small sheets of glass on some non-stick aluminum foil. I mixed a bit of resin/hardner as per instructions. I applied the resin to the glass, and squeegee the air and excess resin out. I let it sit. I am simply doing this to get a feeling of the time involved in curing and whatnot.

It?s been an hour or more so far, and the pieces I have done are still flexible and rather soft. I cannot see sanding this in it?s current form. Is this what I am to expect? Does the glass get harder the more layers you put on? Am I to expect this glass/resin to get hard like amber or something?

I?m confused. Can someone give me some information?

Thanks
Bob.

 

[Driven1]

Re: Basic fiberglass question.

The glass, when fully cured should be very hard almost to a point of being brittle. Depending on humidity, temp conditions, and how much hardener was used, it could take anywhere from an hour or so to a couple of days. If poorly mixed, some of it may never harden.

The trick is getting a sense of how much hardener to use under various conditions to achieve your desired working time. The more hardener you use the faster the cure time. If you over-do it, the glass will harden up faster than you can work with it. It's also very important to do a really good job of mixing the hardener and resin.

It sounds like you could have used a little more hardener in your practice piece. It should harden up eventually just as long as the resin/hardener was mixed well.

 

[oops!]

Re: Basic fiberglass question.

It's also very important to do a really good job of mixing the hardener and resin.

this is a main factor.....you cant just swish it with a stick.....you need to really mix the resin......shake the stuffings outta the can before you add the cat.....(at least 3 mins of shaking)

add cat between 1.5 to 2.5 ratio for poly resin....

mix the two by scraping the walls and the bottom of the mixing container. stir very thourly.......

you will see the resin "change color" shortly after mixing.......glass fast my friend........cure should be less than an hour.....kick as little as 10 mins.

 

[Ezrider_92356]

Re: Basic fiberglass question.

it still is not fully cured even after its no longer tacky, could take even another 24 hours before its fully cured

 

[AltheaToldMe]

Re: Basic fiberglass question.

Thanks for you replies guys. I'll get this yet.

I just mixed another batch making sure that the resin was mixed/shaken thoroughly, hardener was 4 drops higher than recommended for an ounce and made sure the mixing was thorough. I layed 5 layers of light cloth this time instead of one. I am also playing with the mixture of Marine-Tex and not having much better luck with it...that is the least of my worries.

I have Bondo resin (polyester) for the bulk of this job, but I also have another type of resin that I got from work. It's a deep red color and in a quart can.. Is there a visual difference between Epoxy resin and polyester resin? Perhaps the red is epoxy resin. In that case, I will use it.

 

[Robj]

Re: Basic fiberglass question.

Once you epoxy you cannot use poly over it. Regarding mixing ratios I use about 1% or about 8ml's catalyst per litre of resin. Sorry Oops but 1.5 to 2.5% would result in very short work time. I have never used 1.5%, only upto about 1% . Your resin should harden in a few hours. I try and have a working time if at least 1 hour, or even more. Many times even after a few hours it has not yet cured fully but by the morning it is solid. IMO you are better off to have your resin kick a little slower than too fast, up to a point of course.

Have a great day,

Rob.

 

[AltheaToldMe]

Re: Basic fiberglass question.

Ok...so no poly over epoxy, but I can go the other way with epoxy over poly.

Is there a visual difference between Epoxy and Poly? The red stuff I have...is it Epoxy? There is no can label so I don't know.

One more thing...I was told that Marine-Tex will funtion much like a gelcoat layer. I was told that if you dry sand carefully, wet sand with 300-1200 grit wet paper and use a rubbing compound that Marine-Tex will take a coat of wax and be as shiny as ever. Am I being led astray?

Right now, I have a test bed of Marine-Tex that I will try finish in the way I described above. I guess we shall see.

You guys are great and I really appreciate you taking the time to answer my questions.

 

[gcboat]

Re: Basic fiberglass question.

First off the Marine Tex does not dry to a bright white such as a gel coat will.
It does dry white - but on the 'muddy' side. You could try and add some colorant to the Marine Tex - make sure it is epoxy compatible - and see if it won't brighten up some, but I don't think it will ever meet the sheen level you want it to be.

 

[jonesg]

Re: Basic fiberglass question.

That can of red stuff could be tool resin, the poly tool resin (for molds) I had was almost orange colored. Its supposed to be sprayed onto the waxed plug for the intended mold, it makes for a very hard ,pinhole free ,mold surface.

or it could just be color base, I had a can of white, used for coloring plain poly resin...uh...white. Thick like sour cream, almost a paste.
If its poly it'll stink like er..stink?

poly just plain ole stinks like a massive gas leak ,
epoxy is much more milder in the smell dept.

Either way, stir it before using, theres probably a lot of solids at the bottom.