anyone used special spray glue to fix dry fibers overhead before lamination?

[jordanbettis]

The success of your repair is going to depend substantially on how forgiving the materials you use are. Instead of using tirax roving and then trying to "fill" the inevitable gaps in the laminate with microbaloons why not use mat-baked glass like 1708? This product is designed for repair work and the purpose of the matting is to absorb excess resin and fill gaps between the layers.


Also microbaloons don't contribute to the strength of the resin. They make it lighter and easier to sand. They are not a reinforcement, collidal silica is.

[Wanderbird]

Originally Posted by jordanbettis

The success of your repair is going to depend substantially on how forgiving the materials you use are. Instead of using tirax roving and then trying to "fill" the inevitable gaps in the laminate with microbaloons why not use mat-baked glass like 1708? This product is designed for repair work and the purpose of the matting is to absorb excess resin and fill gaps between the layers.


Also microbaloons don't contribute to the strength of the resin. They make it lighter and easier to sand. They are not a reinforcement, collidal silica is.

1708 with epoxy? Yuck. Epoxy layups and matt don’t mix.

[Franziska]

Originally Posted by jordanbettis

The success of your repair is going to depend substantially on how forgiving the materials you use are. Instead of using tirax roving and then trying to "fill" the inevitable gaps in the laminate with microbaloons why not use mat-baked glass like 1708? This product is designed for repair work and the purpose of the matting is to absorb excess resin and fill gaps between the layers.


Also microbaloons don't contribute to the strength of the resin. They make it lighter and easier to sand. They are not a reinforcement, collidal silica is.

I think you might not have read the thread fully.
The idea is to replace the foam core and sand it to fairness as good as possible.
Then instead of using the 750g heavy triax with several layers of a much lighter lighter triax of 400g.
After 2 Layers =800g giving strength, there will be some areas which still need more fairing/shaping this will be achieved with the fairing mix. Once that is cured all will be nicely faired and smoothed before adding a final layer of the triax with Peelply on top


This is a fully overhanging epoxy job on a hull, so no advantage of the mat component you propose in my eyes.


Btw.
Did you actually ever use triax? Goes on very nicely. Even several layers wet in wet.

[jordanbettis]

1708 works with epoxy and has been used successfully many times. It is harder to wet out glass with epoxy in general than polyester. Fin rollers are a must.


There is some argument that epoxy doesn't dissolve the binder that is often used in matt but the matt on 1708 is stitched not bonded.

[Wanderbird]

Originally Posted by Franziska

Thanks, you raised an important point regarding where the fairing compound goes.


I adjust. We will laminate the first two layer (2x) 400g triaxial directly onto the, by sanding as good as possible faired foam after brushing a thin layer of very lightly with silica thickened onto the foam.


We will fair after these two layers a bit more with a stronger fairing mix:


Microballoons 3-4parts
Silica 1Part
Milled 1mm fine glass fiber 0.75 part


The milled glass in this mix improves shear strength.


I will also add the Kevlar tape over the keel at this stage. Once this has cured sand smooth and apply last layer of Triaxial.


Regarding scarfing the perimeter outside skin more then the 7cm I'm not sure if this will that much more benefit, remember the original outer skin is 750 triax + 200g biax, so, quite thin.


Anyway thanks very much for the thorough answer and raising an important point. It was counterintuitive to me at first not to add the fairing directly onto the foam, but you're right, structurally its much better to go with the glass against the foam.

Nice. Make sure to bury your kevlar tape under a ply of regular glass, you cannot sand kevlar, it will fuzz up on you if you do. Also, are you laminating with e-glass or s-glass? I would definitely suggest s-glass for a critical laminate this thin. Might be wise to find out what the original layup was and match that though, you wouldn’t want your repair patch to be stiffer than the surrounding laminate. I would expect s-glass for a build like this, it’s the next best thing to going to carbon/kevlar but much, much cheaper.

[Wandering1]

Originally Posted by jordanbettis

1708 works with epoxy and has been used successfully many times. It is harder to wet out glass with epoxy in general than polyester. Fin rollers are a must.


There is some argument that epoxy doesn't dissolve the binder that is often used in matt but the matt on 1708 is stitched not bonded.

Have you ever tried to use 1708 upside down? Thr guys in our local yard were recent.y repairing a 45ft rib that ran into some rocks. Thr original construction was 1708 cloth. The surveyor said they should use the same 1708 to repair. Upside down that stuff is very difficult to use unless you use small pieces, thoroughly wetted out first, and have two people to install it. They were using 2ft x1ft pieces and swore a lot!
By comparison, we laid up 2 layers of 7oz biaxial cloth to the underside of our hull, pre wetted in 5ft wide x6ft pieces, rolled onto a plastic tube. It went extremely well. With a solvent free epoxy we could add additional layers when the epoxy had cured with a 4 day window and no sanding in between. We just peel plied to give a good finish for the next layers

[Franziska]

Originally Posted by jordanbettis

1708 works with epoxy and has been used successfully many times. It is harder to wet out glass with epoxy in general than polyester. Fin rollers are a must.


There is some argument that epoxy doesn't dissolve the binder that is often used in matt but the matt on 1708 is stitched not bonded.

Stitched would be fine, but you loose strength due to the mat layer.
Secondly fiber orientation on the biax is different to the triax. You miss the longitudinal component.

[jordanbettis]

Again I'm arguing for the most forgiving materials rather than the highest performance. But it's your project.

[Wanderbird]

Originally Posted by jordanbettis

1708 works with epoxy and has been used successfully many times. It is harder to wet out glass with epoxy in general than polyester. Fin rollers are a must.


There is some argument that epoxy doesn't dissolve the binder that is often used in matt but the matt on 1708 is stitched not bonded.

Sure it works, but why? It’s just the shortest path to a rich, heavy, brittle layup in epoxy. Never seen anyone suggest that epoxy doesn’t dissolve the binder in matt (which is starch, by the way). The problem with epoxy and matt, other than it being unnecessary and creating a rich layup, is that epoxy totally dissolves the starch binder almost instantly. Try to do an epoxy layup with just matt sometime and see what happens. The only reason it works with 1708 is because it is generally applied matt side down, so the matt is trapped between two plies of glass. And why do you think it’s harder to wet out glass with epoxy than poly? Are you maybe trying to laminate with regular west system instead of a dedicated laminating resin like Proset or Silvertip? Because I have used thousands of gallons of poly and epoxy, and I find that laminating epoxies wet out faster and better than poly every time. Also, this critical structural laminate is extremely thin. Pretty sure she has no room in her layup for garbage laminate, it’s an ultra light weight cat, not a super heavy mono.

[s/v Jedi]

Yes, 1708 is made especially for epoxy, hence it is stitched. This shows lack of subject knowledge which is remarkable, I didn’t see that coming.

Yes, I used 1708 overhead with epoxy. It was fine. It does exactly what is needed here: adapt to uneven surface and of course the 8 ounce of mat contributes to strength. You have many fiberglass components using nothing but mat.

That said, it’s only a biax but a triax is only a triax so you can go on until every degree of strand direction is included and guess what, that is random strand mat.

For high strength you alternate 1708 with 1808 for quad orientation.

[Wanderbird]

Originally Posted by s/v Jedi

Yes, 1708 is made especially for epoxy, hence it is stitched. This shows lack of subject knowledge which is remarkable, I didn’t see that coming.

Yes, I used 1708 overhead with epoxy. It was fine. It does exactly what is needed here: adapt to uneven surface and of course the 8 ounce of mat contributes to strength. You have many fiberglass components using nothing but mat.

That said, it’s only a biax but a triax is only a triax so you can go on until every degree of strand direction is included and guess what, that is random strand mat.

For high strength you alternate 1708 with 1808 for quad orientation.

Wow, saying 1708 is made especially for epoxy is truly laughable. It is , after all, used with poly by just about every modern builder. I have been using it since long before epoxy layups were at all common in boatbuilding.
Every degree of strand direction also means absolutely nothing when the strands are very short instead of full length, and also not woven.

[s/v Jedi]

Originally Posted by Wanderbird

Wow, saying 1708 is made especially for epoxy is truly laughable. It is , after all, used with poly by just about every modern builder. I have been using it since long before epoxy layups were at all common in boatbuilding.
Every degree of strand direction also means absolutely nothing when the strands are very short instead of full length, and also not woven.

Mat normally uses a binder that catalyzed epoxy doesn’t really dissolve so it isn’t compatible with epoxy. This is what you had in mind when you stated it doesn’t work with epoxy. You said that because you are unfamiliar with 1708 or you would have known that it doesn’t use the binder to make it compatible with epoxy. The reason is that it is designed for repairs, not for new builds, exactly for the reasons you stated, i.e. the mat is much weaker than a biax. The point is that we’re talking about repairs here, not new builds and for repairs epoxy and 1708/1808 is superior to polyester with biax.

[Wanderbird]

Originally Posted by s/v Jedi

Mat normally uses a binder that catalyzed epoxy doesn’t really dissolve so it isn’t compatible with epoxy. This is what you had in mind when you stated it doesn’t work with epoxy. You said that because you are unfamiliar with 1708 or you would have known that it doesn’t use the binder to make it compatible with epoxy. The reason is that it is designed for repairs, not for new builds, exactly for the reasons you stated, i.e. the mat is much weaker than a biax. The point is that we’re talking about repairs here, not new builds and for repairs epoxy and 1708/1808 is superior to polyester with biax.

Can you please quote where I said that 1708 doesn’t work with epoxy? Because I never did. Just that there are much better, more professional options. Typical internet behavior.
I have used countless full rolls of 1708 in my long career in the yards, which has included plenty of both new builds and huge repairs.
It would be much more accurate to state that CSM is not optimized for epoxy than to state that 1708 is for epoxy only, as you have.

[s/v Jedi]

Originally Posted by Wanderbird

Can you please quote where I said that 1708 doesn’t work with epoxy? Because I never did. Just that there are much better, more professional options.

Of course:

Originally Posted by Wanderbird

1708 with epoxy? Yuck. Epoxy layups and matt don’t mix.

1708 is a specialized product combining a biax with mat by stitching and designed to be compatible with epoxy, contrary to regular mat. You obviously didn’t know that as shown in your statement above.

Repairs using epoxy and 1808/1808 are professional. Even with better than expected performance of secondary bonding of polyester with old polyester, epoxy is still the superior option, especially with durability in mind.

[Franziska]

Originally Posted by s/v Jedi

Of course:



1708 is a specialized product combining a biax with mat by stitching and designed to be compatible with epoxy, contrary to regular mat. You obviously didn’t know that as shown in your statement above.

Repairs using epoxy and 1808/1808 are professional. Even with better than expected performance of secondary bonding of polyester with old polyester, epoxy is still the superior option, especially with durability in mind.

No polyester on the boat in question. Completely built in Vinylester.
Will repair with epoxy.


Anyway, what's your preference for this job?
I still lean towards 3 Layers of the 400g Triax.
Beside the better strength it means I only need to order one type of glass.
I'll order a complete roll than anyway as I can use it on many other jobs too and I don't risk running out of material on the job.