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Technical Proverbial Can of Worms-Epoxy Sealer/Primer

Discussion in 'The Hokey Ass Message Board' started by RMONTY, Jul 28, 2020.

    Joined: Jan 7, 2016
    Posts: 2,257


    As I move towards putting my car back together, I have created a citric acid bath to remove rust, which works better than I could have dreamed. My question is this:

    Once the parts come out of the citric acid bath, I want to primer them (using some sort of Epoxy Sealer) so they do not rust, or flash rust again. My progress is slow, but methodical, and I know absolutely nothing about painting with these types of products as a general rule.

    What is the best product (here is where the can gets opened) and what is the best way to get these parts primered? Should I soak them in Gibbs until I get a bunch of parts ready to paint, and do them all at once, or is there a way to efficiently paint these parts a couple at a time and not waste a bunch of paint.

    I see rattle cans advertised but DAMN! They are expensive....and I have never had a lot of faith in spray bombs....

    So what is the best way to go here?
  2. ClarkH
    Joined: Jul 21, 2010
    Posts: 1,162


    Rattle-can expoy primer is 2-component, and has hardener in the can. Once you activate the hardener, you have a 24 hour pot life, after which the contents of the can will be rock hard. That makes it expensive, but also far superior to regular rattle can primer. (Wear a respirator and have no exposed skin. Serously! It's nasty stuff.)

    I would treat individual parts with phosporic as you go (Ospho or Metal Prep brands) until you have a enough to paint a batch.
    belair and RMONTY like this.
    Joined: Sep 8, 2015
    Posts: 883

    from West, TX

    I use Nason epoxy primer available locally. I only buy it in quart size as it is easier to handle and mix. If you use the marked mixing cups you can really get a precise amount of paint mixed up to cut down on waste. I’m afraid it is up to you to guess the amount of paint required.
  4. Nostrebor
    Joined: Jun 25, 2014
    Posts: 1,207


    I do what @DIYGUY does. Nason in quarts, mix a bit at a time to paint a small batch of stuff. After a few tries you get a feel for how much to mix up.

    Treating in Ospho until you have a batch works too, but if your shop is super humid you still may get some rust over time.

    Joined: Jan 7, 2016
    Posts: 2,257


    Climate controlled shop. Humidity is usually in the 30% to 35% range. I keep the temp in there at around 75 degrees.

    Is there any compatibility issues with the primer and paint when it comes time to put color on the parts?
  6. Nostrebor
    Joined: Jun 25, 2014
    Posts: 1,207


    The Ospho thing will probably work fine for you until you have a decent batch if you're climate controlled.

    I usually buy Nason stuff (because we have an account with them at work), so I've had no issues. It will be good to hear from the masses on this one, but typically epoxy primer is good with whatever in my limited experience.
  7. Please read the MSDS and instruction sheet from the paint manufacturer for the proper preparation procedure . This can vary from manufacturer to manufacturer. Rattle can is ok for a small spot repair but for large areas is not practical or desirable.
    Joined: Jun 3, 2005
    Posts: 8,300


    Right before prime you want to give em a rinse in metal prep. It etches the metal and removes any remaining oxidation. Do the rinse in the hottest water you can stand then follow up with lots of air. Wipe with a lint free cloth and prime. What primer? Like oil we all have our loyalties. I like PPG ShopLine epoxy. It comes white or black, costs well under $200 for a gallon "Package" (primer and catalyst), it's easy to use, can be reduced as a sealer, in a decade for me it's been dead reliable. It has a long thermoplastic time, like 72 hrs I believe, but I never give it more than overnight for non-sanding overcoat. Reduced, no more than a few hours when used as a sealer. Yeah, all the temp, humidity etc rules apply. For simple "til I get to it" use almost anything that cleans off easy will do. I'm assuming none of us stores clean shit outside, and extremes are a non-event. That said, I've simply rattled a little Krylon onto small parts just to stave off excess flash rust. Some lacquer thinner when "the day" comes and there's my clean shit ready to go. Etch primer is good too but you must scuff it up if it sits for days, or weeks as some of us end up. Cheap, effective, 2 jobs in one as in etch and protection, but again scuff before final coating work like primers and such. Etching primer is also non-sanding in certain instances, read the label directions. Polyester primers don't like to go over most etch primers, so neither does mud. Just an FYI. Have fun, and don't overthink it.
    Blues4U and Nostrebor like this.
  9. I haven't had to do any painting for a while, but I used to spray epoxy primer in my touchup gun. Easy to handle, little waste, and you only use what you need. Empty, and clean up the gun, and ready for the next batch.
    Nostrebor likes this.
  10. rusty valley
    Joined: Oct 25, 2014
    Posts: 2,916

    rusty valley

    put your unused epoxy primer in the refrigerator, it'll last a week or more. epoxy needs 50 degrees minimum to cure
  11. Paulz
    Joined: Dec 30, 2018
    Posts: 65


    I wouldn't bother with buzz can epoxy.
    When I was doing my epoxy primer work, I hit up my paint guys for a couple of mixer lids for the cans. Worked great and had no problem dosing out small amounts for small jobs.
  12. I would pick what brand you want to use to paint the car in the end and work backwards from there. That way you can guarantee there are o compatibility issues. You don't have to buy the surfacer or color/clear yet, just pick the brand and style.
    rbrewer likes this.
  13. Compatibility issues are overblown. They are a way for paint companies to force shops to use all of their products to retain warranty. A home user is getting no warranty regardless. I have mixed and matched hardeners and paint, sprayed different companies products over each other even mixed various companies products together from just about every major paint company out there and have never had an issue with compatibility.
    theHIGHLANDER and low down A like this.
  14. KenC
    Joined: Sep 14, 2006
    Posts: 661


    Be sure to confirm with maker's tech sheets. Some epoxies specifically state cautions when using over acid treatments, SPI comes to mind..
    metlmunchr and klleetrucking like this.
  15. 31Apickup
    Joined: Nov 8, 2005
    Posts: 2,808


    I’ve seen several sites that also talk about rolling on epoxy primer on small areas, may work if you have small stuff prepped. I just sprayed Kirker Enduroprime, mixed 1:1, no induction time and 90 minute potlife. For An amateur painter waiting for induction to me, then not having enough mixed etc it made sense. Plus temps in the PNW only are in the 70’s for a short period for painting outside. I spent a lot of time looking at the other products out there.

    Sent from my iPhone using The H.A.M.B. mobile app
    ClarkH likes this.
  16. squirrel
    Joined: Sep 23, 2004
    Posts: 50,199


    how long can you leave stuff in your shop without it getting rusty? I live in AZ, and depending on the weather, how often I run the swamp cooler, what time of year it is, etc, I can leave bare steel sitting in my shop for up to a few years without needing more than a scuff to get rid of a few specs of accumulated surface rust.

    Maybe keep cleaning parts, until either you're done, or you notice a bit of rust forming...then mix up enough primer and cover them all.

    but no one else is ever dumb enough to follow my painting advice :)
  17. KenC
    Joined: Sep 14, 2006
    Posts: 661


    I'm partial to PickleX20. expensive but it doesn't take much to do the trick. As long as it is inside and dry, I've never have rust form on newly sanded or blasted metal.

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