406 Colloidal Silica is an epoxy thickening additive used to control the viscosity of the epoxy and prevent epoxy runoff in vertical and overhead joints. This is a very strong filler that creates a smooth mixture, ideal for general epoxy bonding and filleting. It is also our most versatile epoxy filler. Often used in combination with other fillers, 406 can be used to improve strength, abrasion resistance, and consistency of epoxy fairing compounds, resulting in a tougher, smoother surface.
VIDEO: Adding Fillers to Epoxy.
Making Color-Matched Fillets using Colloidal Silica
A great way to make strong, color matched fillets is to initially thicken a batch of epoxy with 406 Colloidal Silica filler to a mayonnaise consistency (this will create a translucent white/smooth and creamy epoxy) then add wood sanding dust until you arrive at a color you are happy with. The translucent white color of this filler is easily overcome by the wood sanding dust. Add a little wood sanding dust and you’ll get a colored epoxy that is lighter than the wood. Add a lot of the wood sanding dust to the 406-thickened epoxy mix and it will become dark.
When 406 is used to thicken the epoxy alone it gives the mix a translucent white look that will nicely offset the darkening effect of wet wood flour (sanding dust) allowing you to arrive at a color that perfectly matches the wood tone. To do this well though, you will need to have a varnished wood surface or an epoxy-coated surface to see what the wood looks like as you try to color match the thickened epoxy for making fillets. What the epoxy looks like while uncured is what it will look like after it cures.
So, if a natural wood finish is desired, you can add to the overall beauty and elegance of a glued plywood structure by using color-matched epoxy fillets.
Read more about making color-matched fillets at Epoxyworks.com.