Mixing paint questions

[ryans69chevy]

Looking for some ideas/procedures on how you guys mix primer/paint. Tonight I sprayed epoxy for the first time and I just want to make sure I'm doing it right and not being wasteful. Its always nice to learn other tips and tricks.

I have small mixing cups (pint size??) that I bought from the paint store that has different ratio marks on them. I mixed a small batch since I had no clue how much I'd need. Ended up needing to mix up another batch since I ran out so I used another mixing cup.

Do people clean these out to re-use them or are they a one and done type item?

Is it smart to put a funnel or strainer or whatever they are when pouring the paint from the mixing cup into the gun hopper? I dont have any, not sure what the point of them are, just remember seeing them on different shows.

Nason's tech sheet shows an induction time of 30 min if over 70 degrees. How precise does a person need to get on that? If you mix and then spray right away, what happens?

I had trouble telling when the first coat "flashed". It was probably 5-10 min between my coats. Once I was spraying my second coat, I could tell where it was laying down. Maybe I was expecting more of a drastic sign or something or maybe I didn't wait long enough between coats for the first one to flash?

If you want to share a step by step procedure from mixing, to spraying, to cleaning the gun that would be awesome.

Thanks,
Ryan

[hugger6933]

Epoxy primer? usually flashes when it stops shining[wet] it starts turning dull it is drying and you can spry you next coat just dont get in too big of a hurry spraying small spot cause you will end up stacking the wet primer on wet primer then when you think you good to go it starts to run. But thats more of a cooler time thing you should be ok this time of year just take your time you will be fine. The mixing cups are meant to be disposable or rinse them out use them to hold screws and clips or whatnot. Strainers are a needed thing cause if you dont you will get a booger to either stop up a nozzle or better yet spit out on your slick primer and make more sanding for you. By the way, there is always more sanding to do. I prime some spots sometimes the size of a quarter or so and I try my best just to mix up a very small amount to of course keep down wastes and costs its just a thing you will get more comfortable after more mixing and spraying. I have sprayed hundreds of gallons of primers and paints over the past 35 plus years I have done this. Jim

[Grounded63]

Every time before you spray epoxy/primer/base, you need to shake or stir the individual components before mixing. Some epoxies/primers can settle out pretty firmly. If you don't have a mechanical shaker. You really need to get a stir stick in there. And make sure you don't have a layer of unmixed material on the bottom. Because just shaking it by hand, will not be enough to dislodge it sometimes. If it's settled out well.

The induction time is needed for the material to start cross linking. Otherwise your spraying two mixed but unreacted components on to your sheet metal. It could possibly lead to an adhesion issue.

When the epoxy goes from glossy/wet looking to low sheen/eggshell it has essentially flashed. If it looks like it has dulled out some. And you give it a quick spray, with just some air from the gun. If it dulls out more then glosses back up some. It's not fully flashed yet.

You can reuse that first mixing cup and strainer for the same spraying session. Assuming that your working proficiently. The epoxy residue hasn't kicked off, or dried in the cup / strainer.

If your using a disposable cup system. Like 3M's PPS. You can mix directly in the cup/liner without pre straining your components. Being as they have a strainer built into the lid. But, it's kinda extra insurance. Even though I use the 3M system, I still tend to mix in a mixing cup, and then strain into a cup liner. I always use strainers when transferring mixed components from one container to another. My local paint supplier will usually give me a few strainers/sticks/mixing cups for free. When buying materials from them.

So . . . Clean ( wax & grease remover, or post sanding cleaner. ) your items to be sprayed. Once that is done, I'll usually go mix up what I'm going to spray. Then come back, air spray and tack rag the items to be sprayed.

Shake/stir individual components. Use separate stir sticks for each component. DO NOT cross contaminate catalyzed materials.

Pour/measure components into mixing cup. And stir well. If it's just a resin and activator it can incubate in the cup with a paper towel over it. Then stir well again, then strain into the gun. If it's also blended with a reducer I'll strain it immediately into the gun and cap it. So the reducer is not flashing off while your waiting for the induction period.

Once your strained into the gun. Wipe the sides of the mixing cup with the stir stick. So you can see your mix ratio. Right before I spray , I will wipe down ( with a tack cloth ) the outside of the gun, my gloved hands, and the first 5/6 feet of the hose. Whatever may be over hanging the parts to be sprayed. ( I usually have two tack cloths on hand. A " clean " one that is paint only. And stored in a zip lock when not in use. And a " dirty " one that is used for wiping down the outside of the gun/hose. It's not really dirty just a well used old, paint only one.

Spray parts . . .

If you have material left over from your first coat. But clearly not enough for a complete second coat. Strain the material from the gun back in to the mixing cup. This will show you how much material your using per coat. And how much more you need to mix up. For your next complete coat. Strain this back in to the gun. Then mix up the additional epoxy needed to complete the second coat. Once it's incubation period is done, strain it into the gun also.

[ryans69chevy]

Appreciate both you guys on the detailed description. I'm going to have to get some strainers. I'm just doing epoxy right now. The details provided help alot. I've sprayed 3 different "sessions" and each time it's better. Can't wait to get more parts in the booth.