Fibreglass matting

[Guest]

I use the fine variety of this material on the inside of the (planked) hull, but find that the 'dabbing' technique rarely works for me, (the matting inevitably shifts).

On the current build I cut the pieces to shape and held them in place with a few drops of cyno (superglue) before a liberal application of polyester resin. This worked but I did notice quite a large heat build up as the stuff dried out. The heat was significantly more than you get from the "natural" setting of the resin.

Any scientists out there that can explain this?

J.

[Guest]

Strange phenomenon. The heat generated must be the same for the same constituents in the same quantity in an exothermic reaction.

The things therefore that would have an effect would be:

1) Insulating properties of the the hull being coated forcing all the heat to dissipate inwards

2) Quantity of resin involved.

3) Rate at which the heat can dissipate which is dependant on the available surface area. This may be a possibility if you are not actively spreading the matting around during the curing process and helping the heat to escape.

Apart from that I haven't got a clue!!!

[Guest]

Howdy John,

:thinking:

Well, I sometimes read things in books or online just out of curiosity and it just so happens that no more than 3 weeks ago, I was reading up on cynoacrylate esther (super glue).

So, I went back into the history on my computer and looked for exactly what you were describing....I knew I had seen an explaination similar to what is happening to you.

So, this is the best explaination I know of:

Exothermic reaction:

Cyanoacrylate will produce exothermic reaction (heat) when it is polymerized (resinified).

The heat gets particularly high when large amounts of cyanoacrylate permeates a porous material, such a woven cloth or urethane rubber, and quickly solidifies.

If an accelerator such a s caustic soda or amine is contained in such materials, the exothermic reaction will take place so strongly it can cause burns.

As you can see, woven cloth is exactly what you are using. I know from personal experience that a drop on your blue jean pant leg will burn you...not to mention stick your pant leg to your leg.

Now I dont know what all is contained within fiberglass, (chemical wise) but fiberglass is woven thread which consist of thousands of filiments per "thread" so you have alot going on there as far heat possibility.

Anyway if you would like to read the entire article, you can find it here:

http://ajh-knives.com/adhesive-1.html

The above excerpt is from the last entry on the page.

For more info, try a google search on "exothermic reations and cynoacrylate esther"

hope this helps explain a few things,

Greg

does this make me a geek? lol

[Guest]

lets not get confused here

1 it gets hot due to chemical reaction

2 see 1

3 I am not clever just lubricated enough lol

[Guest]

lets not get confused here1 it gets hot due to chemical reaction

2 see 1

3 I am not clever just lubricated enough lol

That's about the size of it Nigel!!

Oh and GW, if that doesn't make you a geek I don't know what will!!!

Great explantion though!!

[Guest]

See i know at least one person understands me

[Guest]

Thanks GW, I had thought about "accelerants" but wrongly considered that the cyno somehow accelerated the resin. Now i see the heat came from the matting/cyno amalgum.

BTW, if you use cyno, be very careful with naked flames. I used it to bind some wire into a net structure with fine spacing (about 1.5mm) for a project. Rather than try to glue each strand i figured it would be easier to coat the whole lot then 'fire' the "holes".

When I applied a match the whole lot went up in very short order, almost like phosphorus and the 'net' disintegrated. (There was also a nasty smell).

I did ensure safety specs and respirator were in place before the "experiment" so no harm done.

On the other hand the fact that cyno 'unglues' if heated is quite useful, i often use a drop on metal parts for machining/polishing then a gentle heat from a lighter is sufficient to release the hold.

J.

[wonwinglo]

If you want to avoid the Thermo compatibility problem in future,then instead of using cyno use 3M Spraymount adhesive to bed down the glass fibre matting,you will not need much just enough to make it sit prior to applying the resin.

You will find it superior to cyno as it grabs straight away and more evenly,use a stiff brush to push the matting into any crevices.

[Guest]

A good tip Barrie.

To be honest I was not worried about the heating effect, it may even have worked as an accelerant. The particular model's access will probably preclude the spray you refer to but something to bear in mind for others.

J.