Fiberglassing

[Tmacmi]

I don't know much about fiberglassing and could use a little confirmation.

There are two partial bulkheads, that the black water tanks sit on. They top out about 12" above the deck. There was a 1 1/2" hole that the water lines ran through. The hole was way too tight and jamming the hoses and preventing water from running into the bilge. I opened them up so the hoses had more room and water could run to the bilge.

That opened up some fresh plywood. I want to seal that up. It is cold outside, it might be able to get up to 50 degrees with a low of 40 degrees for a while. I've done some reading. It looks like West Systems 205 can handle the cold the best. I can also heat the surfaces a little with a heat gun and keep the area warmer under a tent.

So I'm thinking West System 205. The question is what fiberglass fabric?

Thanks, keep safe and healthy!

[rbk]

Originally Posted by Tmacmi

I don't know much about fiberglassing and could use a little confirmation.

There are two partial bulkheads, that the black water tanks sit on. They top out about 12" above the deck. There was a 1 1/2" hole that the water lines ran through. The hole was way too tight and jamming the hoses and preventing water from running into the bilge. I opened them up so the hoses had more room and water could run to the bilge.

That opened up some fresh plywood. I want to seal that up. It is cold outside, it might be able to get up to 50 degrees with a low of 40 degrees for a while. I've done some reading. It looks like West Systems 205 can handle the cold the best. I can also heat the surfaces a little with a heat gun and keep the area warmer under a tent.

So I'm thinking West System 205. The question is what fiberglass fabric?

Thanks, keep safe and healthy!

If you’re just looking to seal the freshly cut ends of the plywood you don’t need any cloth.

[mike d.]

Chopped strand mat, is the easiest to form around edges ! You can use regular resin ! I used it mid winter, Mixed it in 20-25 degree weather, did my work, then put a heat lamp on it over night, at a safe distance ! I went out about 2-2.5 ft ! It was just to warm up the layup to kick the resin ! Worked quite well, no sags, or drips ! This was for replaqcing core from underneath ! Note surveyor inspected and said he wished more people did it this way ! What you are trying to fix is non structural, only cosmetic ! Wet out the wood with resin, then lay on the csm, then apply just enough resin on top to wet out, no more than to make the mat fiber dis.appear, from white to translucent !

[s/v Jedi]

No, don’t use chopped strand mat with epoxy: it is incompatible. I recommend using a light cloth. It sounds like you can use something like a 2” wide tape.

Like others write, you don’t need any glass. I recommend you just brush it with penetrating epoxy a couple times with 1-4 hours in between. I started using the penetrating epoxy from Total Boat and like it

[rslifkin]

There is epoxy compatible CSM out there, but you have to specifically find it, as most CSM needs styrene to dissolve the binder and won't work with epoxy. The epoxy compatible stuff is usually a bit more expensive, but I've used it and can confirm it works just fine.

[Chotu]

Just another vote here. You don’t need any Fiberglass to seal that up. Just epoxy it with a couple of nice layers of neat epoxy. Good to go. Fiberglass serves absolutely no purpose in this application.

For extra penetration, heat it way up then let it cool down as the epoxy kicks. The wood will then suck the epoxy into the pores as it cools.

Don't do the opposite. Don't apply epoxy to cold wood then heat. The off gassing will make bubbles everywhere in the epoxy.

[Rucksta]

Originally Posted by rbk

If you’re just looking to seal the freshly cut ends of the plywood you don’t need any cloth.

+1

Use a low viscosity solvent free laminating resin.
Or go ghetto with some 5 min Araldite.

Wipe it on with a gloved finger.
2-3 coats until the surface is glossy - smooth is optional but desirable.

Resin may be thickened with glue powder on subsequent coats - not initial, you need the penetration into the timber structure.

Epoxy barrier coat is also suitable of subsequent coats if there is any movement between the hose and the hole. It is very hard wearing.

Don't be overly concerned about temperature and set up times.
The stuff will eventually go off.
Slow set is a problem for maintaining productivity in a layup schedule.

Another trap is to mix extra hardner.
This results in the excess migrating to the surface as the resin cures resulting in an amine blush.
The blush inhibits adhesion of subsequent coats and must be mechanically removed.

Avoid CSM The usual emulsion types require a resin with solvent.
As the solvent evaporates it leaves micro pores which increase the permeability of the laminate.

Without a solvent the emulsion leaves by products in the mix which enhance osmosis.

P.S. Laminate is two or more layers.
Single layer of cloth like a single coat of paint is ineffective.

Opps - too many words for a simple job. Hope it helps as you move onto more complex fiberglass tasks.

[Lepke]

I use chopped strand mat all the time with West Systems. Epoxy breaks the bond between fibers, but if you work quickly you can wet out the csm without problems. My entire deck and cabin tops are 2.0 csm on an 83' wood boat. At least 1500 square feet.

You need good rollers.

[Tmacmi]

So it sounds like this is the way to go:

TotalBoat Clear Penetrating Epoxy Sealer

Thanks Jedi

FWIW I like Jamestown as distributor in general, but also because they support one of my favorite YouTube Channels-Acorn to Arabella

[s/v Jedi]

Originally Posted by Tmacmi

So it sounds like this is the way to go:

TotalBoat Clear Penetrating Epoxy Sealer

Thanks Jedi

FWIW I like Jamestown as distributor in general, but also because they support one of my favorite YouTube Channels-Acorn to Arabella

That’s it. I just completed a test where I took 3/4” thick birch plywood, sealed it with this epoxy, then scrubbed it with water to remove any amine blush, sanded it, then coated with Epifanes varnish and it worked great

[Tmacmi]

I have a follow up to this.

I want to go and epoxy this open wood this weekend. Its going to be 45 degrees at noon when I apply and then it will have a low of 39 degrees over night.

I can be there from noon until 5 pm with a heat lamp. But I need to leave by 5 and take the heat lamp there. Is that enough time to get the epoxy going?

[rslifkin]

Use fast hardener and you'll be fine even without added heat at those temps. It'll take longer to fully cure in the cold, but it'll cure just fine.

[Thumbs Up]

Originally Posted by Lepke

I use chopped strand mat all the time with West Systems. Epoxy breaks the bond between fibers, but if you work quickly you can wet out the csm without problems. My entire deck and cabin tops are 2.0 csm on an 83' wood boat. At least 1500 square feet.

You need good rollers.

There is chopped strand mat that is compatible with epoxy. But the stuff that isn't turns the epoxy all milky, is hard to get the bubbles out and conform, and seems to give a weaker bond to whatever it is stuck to. (In my experience)

[Chotu]

Originally Posted by rslifkin

Use fast hardener and you'll be fine even without added heat at those temps. It'll take longer to fully cure in the cold, but it'll cure just fine.

+1 on this.

I would bring the heat lamp anyway. Because it will enable you to dry that wood out nicely and have it sucking the epoxy into the pores as it cools. Makes a great seal that way.

And don’t worry if it’s not completely kicked off when you leave. It will eventually kick off. Using fast hardener will help, but it’ll be fine no matter what.

If you look up something called a pre-Preg, that’s exactly what it is. Refrigerated epoxy already mixed. Starts to kick as soon as the temperature is right. Yours will do the exact same thing if it's still a little chilly.

[CassidyNZ]

Originally Posted by Thumbs Up

There is chopped strand mat that is compatible with epoxy. But the stuff that isn't turns the epoxy all milky, is hard to get the bubbles out and conform, and seems to give a weaker bond to whatever it is stuck to. (In my experience)

In my experience the most common form of glass fibre is E-glass which, unless you specify some other spec (A-glass, D-glass, R-glass), is what you’ll get when you buy it. I’ve used this in chopped-mat form, glass cloth and rope with epoxy and polyester resins since I was a kid building my own surfboards (and that was a long time ago). I’ve never experienced any combination of resin/glass fibre that was incompatible.

Learn something new every day as they say.