fiberglass cure time

DougM · Mar 29, 2011

depending on the resin and hardener used the product could "kick" in as little as 10 to 20 minutes at 70 degrees or above, a little longer at lower temperatures. More hardener to a point will accelerate the process.

The glass won't fully cure to the point of being able to do any serious work on it for about 24 hours.

FourPoints · Mar 29, 2011

redhead78 said:
Hi all I have a ? on fiberglass cure time. I am going to use fiberglass cloth, and a resin and hardener over some wood in my salon cieling, temps will be around 50 to 60 F. How long b4 I can rough up and glue and screw 7/16" wood T&G wood to it?? Thanks Red

depends on what hardner and resin combination you use.

for a detailed explanation check out http://www.westsystem.com/ss/cold-temperature-bonding/

Ross · Mar 29, 2011

Are you using epoxy or polyester resin? It makes all of the difference.

Merlin Clark · Mar 29, 2011

These chemicals are toxic so please take adequate precautions.

Ross · Mar 29, 2011

Probably polyester. You should be able to start sanding in a couple of hours.

Snotter · Mar 30, 2011

The secondary bond between the old and new glass will be superior with epoxy. Use a cold-weather hardener and you should be able to work it the next day. I would recommend a space heater to facilitate a good cure. Sanding may require another week.

woodster · Mar 30, 2011

redhead78 said:
the resin I got a at a body shop supply I will check it to see which it is.

in as much as i have always been a big fan if that type of epoxy......in the past year and a half i have come to be a bigger fan of the West Systems Epoxy.....
1...it is not near as messy when using
2...you only use the amount you need because of the pump dispencers that you get with them
3...it doesnt shrink like the body shop stuff does
4... there is no guessing about the mixture when useing the pumps
5... when you are through with it you just set it aside till the next project
6...priceing is about the same as the body shop supply stuff

regards

woody

RichH · Mar 30, 2011

Since you are using a polyester resin, suggest you make up several samples (in small paper 'medicine' cups) with varying/differing amounts of catalyst. Simply observe the time that it takes for each 'cup' to kick. The slower the cure the stronger the bond. Dont exceed 5% catalyst.

Merlin Clark · Mar 30, 2011

redhead78 said:
Hi all I have a ? on fiberglass cure time. I am going to use fiberglass cloth, and a resin and hardener over some wood in my salon cieling, temps will be around 50 to 60 F. How long b4 I can rough up and glue and screw 7/16" wood T&G wood to it?? Thanks Red

Red,
Can I ask why you are sealing in the wood? I had a 9 yo Rhodes Traveler that had been someone elses (new but unfinished) project and the only rot in the decks was where the PO had sealed from beneath. The rest was bare fir ply and solid as new.

tommays · Mar 30, 2011

The strength of the core sandwich comes from the core material having glass on both sides of the core

With no glass on one side its not going to be at all strong and i am really unsure about how well the 5200 is going to work or how long the core material will last without rot

Merlin Clark · Mar 30, 2011

redhead78 said:
Merlin, I have an area soft around 4 wide and 5 long, I removed old balsa core, and glue 3/8" x1.5" wood lath side to side, I had wet it and pre bent it with a slight curve of the deck, then glued it up in place with 5200. My plan was to glass it thee glue up and screw 7/16" t&g x2" the opp way front to rear for strength,then reistall my flp cieling panels. It may not be by the book but it will be strong, and if I got the leaks it will be fine. Do you think I don't need the glass b-4 the 7/16" t&G ??? Red

=====

Sorry, my wee mind was fixed on plywood core and less- than- fastidious bedding to avoid leaks.

Sounds like you have a plan, sorry to interrupt.

Merlin Clark · Mar 30, 2011

In between would add stiffness to the laminate.
I've built frames in place with 1/4 strips of fir epoxied together and used bronze ring nails to hold the strips in place until the (thickened) epoxy kicked. Very strong and much easier than building the laminated frames and then trying to fit to the overhead.
Tommays has a good point about the sandwich FG- core- FG. I don't know anything about coring with soft materials like balsa except that if the coring is mostly sealed up and a screw hole allows water in, eventually there will be problems but sounds like you know plenty about this!
Sounds like you formed plywood in place with the arc it needs- should be real strong.

tommays · Mar 30, 2011

after the rip out

Kind of should have done this

And ended up with something like this

Merlin Clark · Mar 31, 2011

Wow! Great job Tom!

shemandr · Mar 31, 2011

I have a few questions re Tommay's repair.
How did you keep the core material up against the upper skin while the resin kicked? I can only imaging a one arm paper hanger rountine.
What is the core material?
Is it separate blocks? Did you have to shape the upper side of the core pieces to fit the lower surface of the upper skin?
And, great job!

tommays · Mar 31, 2011

Well

You have to look at how a boat is built to decide inside skin or outside skin

The Cal 29 does NOT really have much of and inside skin in terms of even minor weight holding ability as compared to say a J24 which has a really thick inner skin

Once you pop off one of the skins the boat pretty much has ZERO ability to support weight or keep its shape

I used 1/2' balsa which is made in 2' x 4' sheets of small blocks held together with some stuff so you can cut to size and worked my way up to being able to do a 12" X 24" section without bending the boat

I used 1/8 masonite wrapped in wax paper to stop any sticking and you do a dry fit and cut the sticks and mark them and then mix you adhesive of choice and put it up and after it kicks move on to the next piece

You keep at it and next thing you know the hard part starts putting up glass upside down