Like conn said it depends on the type off product you are using I have used the west system / smith finishing resin and z poxy
west was a great product however takes to long to cure aprox 48hours or more zpoxy you can sand in 3 hours
remember when it comes to epoxy resin anything over 30min is not a stronger bond it is just longer working time
anyhow resin needs to be thined to the point where it is not tacky so it doed not tug on the fabric while you are spreading it.