It appears that the cylinders in my epoxy pump which is the adjustable the factory (velocity) sells are grinding off a slight amount of metal into my epoxy.. It is a very fine dust that has progressively gotten worse and worse and the pump is only 6 months old.. well, 150 hrs of building time... Has anyone else experienced this..? Today I broke the thing down entirely and noticed wear marks on the cylinders which supported my theory that what I was finding in my epoxy (mainly in the resin side), was metal dust. Is this particularly harmful to the integrity of the layups?I also have ocasionally seen a bit of gray-looking stuff from the resin side. I find that it only occurs after not using the pump for some extended time period, and concluded that it is some reaction product. I have never seen it when using the pump regularly.In any case, it is a good idea to occasionally check calibration of the pump; as I have found that it can change. I checked calibration before starting the project, and then didn't check for a year or so. When I did I found it was coming up short on hardener. Not by a bunch, but I don't know what the tolerance is. I always monitored for any macro changes in cure times or hardness, and didn't observe any changes.If you don't have a gram scale to check it; an easy volumetric calibration can be made. Take some clear tube (I used vinyl) with a 1/2" or so i.d.; cut a couple of pieces about 5" (12 cm) long. Cap one end (like maybe epoxy them to a little piece of wood and space them apart about the same distance as the outlets on the pump). I used a cm scale and marked one at 4.7 cm and one at 10 cm; thus giving the 47/100 ratio by volume. Hold these under your pump and give it a stroke until the resin side comes up to the 10 mark. The hardener should come up to the 4.7 mark. Adjust as necessary. I would be good to use a tube large enough to contain a full stroke of the pump, or more.I am also curious what epoxy it is the factory uses on all the stuff they make.. I'd been told they use ez 84.. Which happens to be what I bought from them.., i guess I'm wondering why my ez 84 turns out more of a golden brown to brown color while theres is more like a green lime color... Anyone know why? Has my stuff just sat in the sun to long? My kit is one of the older RG kits which I then updated to an elite.. So most of my older parts are that deep brown color.. But all of the newer stuff the factory has sold me is that lime green.. I'm confused..I think the color is mostly a matter of the shelf experience of the hardener. The older it is or the more temperature cycles it has gone through, the browner it gets. Also affected by humidity. Oxidizing of the amines. Of one gallon kits I've gotten from local Aircraft Spruce, one can of hardener was dark with some crystalizing and one was the translucent green.If it gets really dark, or contains some crystalization; heat it up to 120-130 F for awhile and it will tend to clear up and the crystals will re-disolve. The resin will also sometimes get cloudly, or have white sediment. Again, heating will clear it up.Hope this helps.Al Gietzen