Laminate Sample #13: Open Molded E-glass / Polyester Resin with Balsa Core

This sample shows how to (kinda) laminate an open molded balsa cored panel with polyester resin.

It is similar to #6 and #8, but this time I'm trying out an end-grain balsa core. It's hard to see how well your core is bonded if there's gel-coat, so this one is just clear resin in one shot. Turns out there were some significant voids/bubbles of trapped air under the core.

This is one of the big problems with coring open molded parts - it's hard to be sure your have the core bedded down completely. Two possible fixes for this are:

1 - use a thickened core bedding putty and place the core down starting on one side and working it in a line so air gets pushed out the "front" for the joint.

2 - use weights (or a vacuum bag!) to press the core down into the first skin. Let the resin gel and then laminate the top skin. For larger parts, this multi-step process is the only option because the gel time of polyester resin is typically pretty quick.

It is a rugged and easy to build laminate and is suitable for projects where light weight is less of a priority but cost, gel-coated surfaces, and molding of complex geometry (in un-cored areas) are important.

Find more about this sample at:

[margadabeginner]

Excelent content, greetings from Ecuador!

[nossrc]

You can do all steps like you do same day ?

[juanm.castillo]

I am interested to know how tight a radius I can build with Balsa,

[adoczka]

Hi, could you explain what is that black mat(?) that you are working on?

[kritizzo]

Anyone need balsa block and core from indonesia?