Combine brushing and spraying epoxy - good, bad, indifferent?

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Evil_Fiz

Promoted Users
My spray "AREA" is for lack of a better word a Dexter kill room in my 2 car garage. It's a bit of work to set up and tear down. Since the garage is used to actually park my wife's car the plastic sheets must be rolled up when not in use. Enough backstory.

I am ready to start reapplying acid to reactivate, neutralize, resand the metal with 80# (AGAIN), and FINALLY apply SPI epoxy to the bare metal. Due to the backstory, tackling this process in small sections to prevent the return of flash rust can get cumbersome and create a lot of extra work if I spray as I go.

- Can I treat/neutralize, sand, and apply a first coat of epoxy with a roller, then when the entire car has its first coat, sand the epoxy and spray 3 additional coats to achieve the proper build?
- If this process is not detrimental to a sound finish are there steps or tips I should keep in mind?

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Emil
 
Don't see why you couldn't apply it with a roller, but I'd still apply 2 coats as I've had rust break through what would be the equivalent of a single coat before after I had blocked a door. If you reduce it 10% it might flow out a little bit and give you a little less work to sand.
 
I have never rolled it on but , I have brushed it on several times.
Evil_Fiz said:
Can I treat/neutralize, sand, and apply a first coat of epoxy with a roller, then when the entire car has its first coat, sand the epoxy and spray 3 additional coats to achieve the proper build?
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Brush or roll a coat or 2 on, when you have every thing protected, 180 DA all the surface to smooth out either the brush or roller tracks. Then spray more epoxy. When I brush it on I let it sit extra long before the next coat.
 
1A Rock said:
... When I brush it on I let it sit extra long before the next coat.
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10-4.
- What is "Extra long"? (24, 48 Hrs.)
- How long should i let it induce for the first 2 coats when brushing on?
- Do you reduce it as Lizer suggested above?
- What grit should I use when sanding by hand in the odd shaped, other than exterior areas?

Thanks,
Emil
 
I wait at least an hour between brush coats. Normal induction time should be fine and the only time I reduce epoxy is when I use it for sealer. Are you asking about sanding grit before or after the epoxy?
 
1A Rock said:
... Are you asking about sanding grit before or after the epoxy?
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I am asking about sanding the nether regions of the car by hand once the entire car has the initial "brushed-on" coat of epoxy. This would be in preparation for spraying the remaining coats of epoxy. For reference, the car in question is a VW Karmann Ghia.

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Emil
 
MJM said:
Personally, I would induce the epoxy at least 12 hours. I would recoat after 12 hours. I would also apply it with tight foam 3"-6" roller.

Before spraying over the rolled epoxy, I would sand the epoxy with 180 grit.
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Would waiting between 12 and 24 Hrs. between rolled coats be a problem? i.e. roll it on in the afternoon then reapply early to mid morning the next day.

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Emil
 
MJM said:
...I want a sh*t ton of material either brushed or rolled on so I have lots of material to sand later.
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My understanding from what I have read here is that the first coat should be light to promote adhesion and he subsequent coats should be heavier to provide build. (please correct me if I have misspoken) Is that applicable only when spraying?

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Emil
 
Only when spraying, brushing is pretty much just do the best you can.
Evil_Fiz said:
My understanding from what I have read here is that the first coat should be light to promote adhesion and he subsequent coats should be heavier to provide build. (please correct me if I have misspoken) Is that applicable only when spraying?

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Emil
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Thank you all for your contributions. I have one last question: How deep or aggressive do the 80# scratches need to be on bare metal? I have never done this before and have no point of reference.

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Emil
 
Evil_Fiz said:
Thank you all for your contributions. I have one last question: How deep or aggressive do the 80# scratches need to be on bare metal? I have never done this before and have no point of reference.

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Emil
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The surface needs to be 100% scratched by the paper with no unsanded shiney areas. if that makes sense? It can't be too sanded.
 
Evil_Fiz said:
Thank you all for your contributions. I have one last question: How deep or aggressive do the 80# scratches need to be on bare metal? I have never done this before and have no point of reference.

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Emil
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You’re making this over complicated.

Just sand it 80 grit, if you can see the scratches in the metal you’re good.

You can go with normal induction time—30 min.

Recoat—normally you’d wait 30 min. Since you’re rolling it on wait 60 min between coats, depending on your temperature.

I would recommend having it thinner than thicker for rolling or brushing so it flows out some and is less of a headache to sand. Which is why I would not induce longer and would also add a bit of reducer. You’re going to be spraying the entire car again after you sand so it won’t matter how much you sand off, but this will make for less work when sanding.
 
Alternatively—you can roll on 3 coats and then sand a day or two later—180 grit. It will sand a lot easier when it’s fresh than after it’s fully cured in 3 mo. This is what I’d recommend doing.
 
Thanks.

@Lizer:
Noted. Fear of the unknown can be crippling. Thanks for talking me down from the tree.

@1A Rock:
I hear you on "It can't be TOO sanded". I already went over the entire car with 80# by hand, in vain, in an effort to remove the acid film. So it will be REALLY sanded. Based on the shiny metal after sanding and return of surface rust, I suspect the acid film is gone but I am not taking any chanced.

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Emil
 
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