Painting motorcycle + sanding questions

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PostPosted: Thu Jan 27, 2022 2:43 pm
Hey guys mild bodywork and painting for the first time. I have read through the stickys and several posts but like many I still have questions.

I'm working on a VTX 1800 motorcycle gas tank and fenders. I had to do some light tapping with a hammer ro repair a dent about size of a fist and completed the surface with bondo.

When I sanded the parts down with 180 grit, I went to 220 and finalized with 320. With all parts looking decent I sprayed 2 coats of FP410 2k HS primer. I had to let it sit for about 2 months and now I'm back on the project.

I initially started to use dry coat and then wet sand the rear fender. Too me it looked like it washed all the dry coat off hence I gather that's why it's called dry coat. At any rate I decided to continue wet sanding with 600 grit to get all the areas smooth. I had read here that if panels and such are straight then I could possibly skip the guide coat. Since it's a bike and it has many curves I figured I would try it.

On the rear fender I sanded to much on some edges and went to bare metal in two places about the size of a quarter.

On the front fender there are four rivets that hold the mounting bracket to the fender. Even though I used a scuff pad around those I still went to metal

On the tank, I sanded to the bondo in one small area again about the size of a quarter, maybe a little larger. On the tank is hard to tell whether it's me as a novice sanding and working on a curved tank or if it's a high spot. By hand it feels very smooth.

So my question is should I respray my FP410 primer on all the parts again with 2-3 more coats and start sanding process over? Or, should I start all over and go with an epoxy primer? ( that would lead to lore questions)

The only bodywork was in the tank area where my pops layed it down. The rest of the paint was good all over except for a few scratches over the years. That's why I only went down to 180 grit to knock the surface down.

If you made it through all of that and understand what I'm asking I appreciate it. If I'm doing something wrong and have some tips that would be much appreciated. Reading through the forums here can get a little confusing because I'm still learning the terminology.

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PostPosted: Thu Jan 27, 2022 4:30 pm
The trick here is to work out whether the areas where you have metal showing are actual high spots or you've just over-sanded around them, creating an encircling low. A stiff block, with guide coat will usually answer this, or you can re-spot prime and sand....gently.
Chris

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PostPosted: Thu Jan 27, 2022 4:35 pm
Any bare metal should be covered in epoxy, it only takes a little, you can even
thin it down to a seal coat. After that, I'd spray more 2K.
If it were me and I wanted a really nice straight finish I would spray
it with 3 or 4 coats of 2K then sand it with 150 to180 grit dry to get it straight, even
curved areas benefit from the coarse sanding.
After that, another coat of 2K (if needed) then sand smooth with 600.
If you want the surface to be straight and consistent you really have to block
the first application with a coarse grit.
Coarse grits like 150 to 180 straighten,
fine grits like 600 smooth.
They are totally different. :mrgreen:
JC

(It's not custom painting-it's custom sanding)



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PostPosted: Thu Jan 27, 2022 7:27 pm
20220126_174011.jpg
Thanks for the posts guys. I will post a couple of pics to show you where I'm at.

JCClark - when you say use epoxy do you mean the same primer I'm using now or something different? I was working on block sanding when I ran into the issue of taking too much off. I think I need to do what you are saying and reprime again. When I block next time I will dry sand and use the dry guide coat.

Initially, I liked the wet sanding because it's less mess but I can adapt to what works best



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PostPosted: Thu Jan 27, 2022 7:29 pm
Another pic
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20220126_173944.jpg



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PostPosted: Thu Jan 27, 2022 7:30 pm
And the tank
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20220126_173922.jpg

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PostPosted: Thu Jan 27, 2022 10:28 pm
I have a painted a few motorcycle parts.

These were sanded and then shot with black epoxy primer. After 24 hours I shot 3 coats of 2k regular build primer, waiting the appropriate flash time between coats.
Fairing Primed 1.JPG


I applied guide coat and used a fairly firm Durablock 2 1/2" x 5 1/4" (or close to that) sanding block for most of sanding, then more guide coat and 320 and finally more guide coat and 600 grit wet on a softer block that has some flex to it.

These are as sprayed with Black Base and Clear Coat.
FairingandFenderassprayed.jpg


Here's the fender after buffing:
FrontFenderBuffed.jpg


Fuel tank:
SPIBlackEuroClear.jpg


Using the right materials makes all the difference and always use sanding blocks and guide coat.

Right Side Rear.JPG
1968 Coronet R/T


ACTS 16:31

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PostPosted: Fri Jan 28, 2022 9:13 am
Any epoxy will be fine for bare metal.
Wet or dry sanding will work just as well, it's just a personal choice,
it's whatever you prefer.
I actually use wet and dry (for different reasons for different things).
I tend to use more dry sanding the colder it gets.
Primer looks real good. :goodjob:
JC

(It's not custom painting-it's custom sanding)



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PostPosted: Fri Apr 22, 2022 5:54 pm
Hey, I wanted to drop by and say thanks for the help. I was finally able to finish the paint and I think it turned out pretty well. Going to try and post some pics.



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PostPosted: Sun Apr 24, 2022 12:19 am
Great work!

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