I would never trust a pump to give me the correct ratios. I always find out the mix ratio by weight and use a gram scale. I transfer the components into bottles much like the old school diner Ketchup squeeze bottles for easy dispensing. I discovered a couple years ago just how critical mixing is as well. I discovered I did not mix well enough. For this reason we have mechanical mixers at work and no longer mix anything by hand. Over mixing can be just as bad as under mixing and will lead to a much reduced pot life. I have been told that overmixing introduces more oxygen and speeds up the crosslink. Adding fillers like micro balloons or cabosil introduce oxygen as well leading to less pot life. Now when mixing a batch of laminating resin, I will mix for a minimum of a full minute for batches up to 4 oz and a little longer for larger batches. Since adopting this practice and weighing the components I have not had a case of gummy resin. I am usually sanding on glass about 24 hours after application and have it powder up really nicely.