Bonding Balsa Core

[Dennyhydrostream]

What's the best material to use for laying down balsa core down ?

[tunnels]

Have used balsa down onto wet glass and also down onto a core bond mix . which ever you chose I used Vacuum bagging to pull down !! main thing is to never skimp on resin any where in the process when using balsa !! . Cut all your sheets to fit properly and then place face down and give a generous couple of resin primer coats while you are placing the glass and wetting it out then rolling it , then place the balsa sheets and vac bag when there is enough resin to completely saturate the face side sucked up from below then you will have a near perfect bond !!
The core bond is similar ,always prime the surface that is going to be against the core bond NEVER USE FAST MIXES of resin or core bond !! and if you sucking down then there should be signs of the resin and core bond coming to the surface through any tiny small gaps !! . When you are ready to glass similar prime the Balsa surface with a generous even coat of resin and allow to harden then start you glassing !!

[Dennyhydrostream]

thanks for you input

[tunnels]

thanks for you input

Before the days of fancy core bond mix's we formulated our own and every place I went to work during those early times had there own magic mix !I
So I took particular notice of the best and that's what I used !!,The basic ingrediance was ordinary polyester resin straight from the drum , then a polyester flexible resin was added along with Talc powder , Aerosil and when it became available glass microfibers and like all good mixes extra promoters to bring the gel time back up to where it should be about at a gel time of 30 minutes at 1.5% of catalyst .
Never mix things like Q cells or micro balloons into any adhesives mixes you make as it is a material for making light weight sanding fillers ,NOT ADHESIVES !!
Its the consistency that's the important part and getting the mix to stay wet so when the balsa absorbs the resin up into the end grain but stull leaves enough resin for the actual mix to be able to do its job and stick well .
I am a great advocate of using balsa as it is only in recent times that core cell has come on the market and is much better than any of the other foams . Core shear where the core fails is one problem but the peelablity of glass off foam this is absolutely frightening and I shook my head in disbelief the first time I saw how easy it fell off!! Balsa on the other hand is the opposite and will tear the glass apart before it lets go off the surface of the balsa .