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I bought some 1708 biaxial cloth with mat to use for the bottom of my next boat and I'm considering abandoning it and buying some biaxial cloth without mat. I used it on a recent project and when I cut into it it had small air bubbles down by the mat part, the biaxial wetted out fine. Paraniod this could effect my build severly I made several attepmts wetting out small pieces on wax paper so I could see whats going on. Tried using a brush, roller, glass roller.....everytime i peeled it off the wax paper it still had little bubbles, or gaps under it where the resin didn't penetrate.

What's the deal? did I buy the wrong cloth? I'm using laminating epoxy and was told this would work well with it by the rep.

I don't know about the air issues that you experienced. But one thing is for sure, none backed biaxall has to be wetted out in place. If not when you wet out say tabs for the sake of this particular discussion, as it sounds like this maybe your method, the none backed biaxall will stretch out like a pretzel when you attempt to lift it off of your wet out surface and apply it on your plywood.
Most of the stuff is just stitched together and will distort to high heavens.

The advantage of the 1708 with the matt backing is that it works really well with epoxy for unfair surfaces and on shapely designs where heavy curved surfaces are involved. The stuff glasses chines really well if your prepwork is so so. Of course some designers cringe at the notion of using it with epoxy. I use 1208 or 1808 in lieu of the 1708 for structual glass applications.

Reading your other post you say this boat is of your own design. So there can be some issues with weight too for small boats. So a proper combination and balance needs to be achieved in the two components, wood and glass so that you do not create safety issue of end up with a "dog".

If you would like straight foward replies, you really need to be more specific. If not you end up wading through multiple posts which takes time to disect and still not get the answer that you wish to get either from your perspective.
Are you actually use epoxy or laminating resin thats polyester resin, since you mention the 1708 glass? This resin does create lots of air on the underside in many cases unless you roll the glass out repeatedly after wet out.

The only place the 1708 will be used is on the very bottom. I chose it to add some thickness and help with grinding on oyster beds and occasional beaching. I learned on my last boat that 3 layers of 6oz cloth can get chewed through very quickly, which is why I'm going with a graphite bottom as well.
Anyway, I am laying the 1708 in place and then wetting it out with resin, The biaxial layers wet out perfectly, just not the mat under. I am using epoxy laminating resin, from FGCI and it's a 2:1 formula and works great! It is what the rep told me to use for the best results and I never had any issues until now, but I don't think the problem is with the resin, perhaps my application of it.
I am thinking of shelving it in favor of 12 or 17oz biaxial with no mat just for piece of mind.

With the 1708 I always wet the surface liberally after first dry fitting the glass and rolling it up on a piece of pvc tube or cardboard tube that some of the glass comes on when I use to buy it in rolls. Then lay the cloth back down aligning with small sharpie marks and then roll it out with a hard roller or trowel depending on how wet the initial coat is. Let it sit for a bit and then wet out on the top and push it around. Temperatures will also cause some outgassing too. But you will also need to babysit it. Even when properly curing out takes place and in the tacky stage, you can still trowel it back down. It takes a lot of resin but does bulk up the surface quite a bit both for protection and strength. Apply Interprotect 2000E over it which does several things, one is to fill the weave. You can do this if your glass does not completely cure and you do not have a lot of amine blush. That brand is really prone to blush, especially this time of year!

This is an upated post with a twist. Today I began the job of glassing my small skeg=keel using 1708. I love the stuff for tight bends and in areas where repeated abuse will take place. I layed a slurry mix of thickened epoxy for the fillet along the keel and layed the tab in place while wet.


I then wet out the fabric just enough and then apply finish cloth overlay, also pulling some resin at the same time into the cloth. Its really nice to be able to work the loose mix with a rounded putty knife shaping the curve and pressing some of the mix along the edges for later.

Of course I tape a guide line which also confines resin and material to a targetted area. I wait for the resin to skin over and then cut the tape line and cut off the extra along the top of the keel leaving me with the bare minimum to clean up and continue the glasswork for the glass shoe.

My next step is to tape the fillet area to keep from having to clean any extra resin off and then cap the shoe with two more layers of biaxall letting the resin skin over and then take my sharp razor knife and cut the hang over off. Thats really important to have some extra so that you have a clean edge overlay, which also reduces the amount of fairing and finishing.







If you look closely you will see the finish cloth overlay which reduces fairing on all of my biaxall cloth uses.
FWIW, there are no bubbles in the job either.

Nice job....we must have had the same or similar teacher!!

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LOL! For some perspective of what you have using structual glass, the sheet of plywood is 4mm. If you look closely even with some clean up of the edges so that it receieves the bottom overlay, you can see almost the same thickness in just one layer of the biaxall topped off with the finish cloth. Thats also without any fairing or topcoat or barrier and bottom paint. The cap gets two layers and all the sundries that goes with it.

Hi
if you using epoxy you should not need chopped strand matt !! but it can be used as it glass fibre reinforces the resin thats under the cloth and to buils a little thickness so dont think of it in a negitive light ,think possitive !!can have the csm uppermost as a sacraficial sanding layer so dont sand into the strands of the main cloth thats there for strength !!
i see nearly every one running for 1708 biaxle glass 0/90 !! why ??? what about using bouble bias 45/45 or even a light triaxle !!! Its availible in 0/45/45 or 90/45/45 !! and down quite light !!
If you really sit and look at your 1708 ,0/90 ,how you are using it ,50% of the strands in the biaxle are doing absolutly nothing at all !!,just lays there and takes up space and soaks up resin !! . across a join or a corner double bias 100% is working and being used plus goes round corners easyer internal or external !! .
I see someone had trouble with bubbles , Dosent any one use peel ply and a steel roller ??and squash the surplus resin and the air all out togther ?? can even use plasitic just need to find the right one
I have been fibre glassing for more than 25 years and have used a squeege once ! some one said here use this !,after 5 minutes i tossed it in the bin ! a short haired paint roller is much quicker and can have a job done and finished in a fraction of the time of playing with a silly squeege !!i also use peel ply all the time on everything goes transparnt and can see any bubbles no matter how small puddles never happen and when its ripped off you have a 100% virgin resin surface to lightly sand and paint .Peel ply can saty on a job for as long as you like while doing other work and if it gets spills and dust and dirt dosent matter the peel ply take it all off when you ready and goes in the bin !!

Ever thought of using the csm as the outside layer ? what about using triaxle with a csm upper most !!as a wearing surface silica sand or fine carborundum powder mixed in the resin and in the paint !!,its what grinding discs and sand paper is made from .
Used it a lot on rescue boats that are continually draged on sandy beachs If you add it to a coat of resin can peelply over the top and still have a smooth surface like it wasnt there !. can eve do combinations of the two together and peel ply over for a smooth surface !!!

You got the right stuff !!Turn it over with the csm on top and use peel ply over top and steel roller it !!! when you sand the csm becomes ths sacraficial layer and you dont touch the strands of the main cloth !! simple ah !!

Glass materials is just bundles of strand all held together the thicker the resin the slower it will wet out , the slower the resin goes off the better so the glass soaks longer and better and the resin penetrates all the bundels of strands .
Always wet out the surface under the glass with a generous amount of your resin first and bring the resin up throught the glass and will bring the bubbles with it . dont be a mizer and try to scimp on resin it only uses what it needs !! use peel ply over the top and will hold the glass place and take out any surplus resin that the glass dosent need !!.If the peel ply isnt wet on the surface when you finished theres not enough resin on the job !!

Glassing it not rocket science ! its just resin wetting out glass fibres ,thats done mostly by capillary action!!! its a completely natural action and you can watch it happening .
Get some strands of the glass and a few dops of resin and watch how it works ! if you understand the process it will save you lots a head aches !!
Its so simple its childs play !! so get up close and personal and learn !!

Tunnels,

Are you using a "serrated" steel roller or a smooth one? Like the fiberglass steel rollers designed to get the air out?

STeve