Painting prep question

[PCO6]

I would be concerned about edge adhesion with just a scuff up... hopefully time will show that it was sufficient!

I'm doing a complete colour change (original Bright Silver to grey) except for under the hood with no edge blending of any primer or paint. I've done it this way before without any problems. I do have a few areas where I'l be going down to bare metal and the whole panel will be primed before painting.

 

[il buono]

As someone who spent 3 summers in a body shop, I can say that it's almost always preferred NOT to sand down to bare metal. The only time we ever did was for sheet metal repair.

The rule of thumb for spraying new panels is if you're trying to color match and the base color is the same color as what you are painting, we would use a base primer/sealer and respray, sanding as needed with the MFG recommended grit.

If you're changing colors, like in your case of going from green to silver, then we would sand with the appropriate grit (again, according to MFG recommendation), use 2 coats of a sealer+build up primer, and then spray color. For silver, I would imagine the proper base primer color is a 15-18% grey (what most grey primers are).

I'm considering repainting my LJ. The overall paint from afar looks good. Shines good in the sun and doesn't have the typical Arizona sun damage. The problem I have are crows feet cracks on the side panels and doors. Seems like the only solution for that is going down to bare metal. Besides picking a paint shop, I just need to decide if I'm going to stay with the black paint or switch it up and go to a lighter color. If I had the skills, I would've loved to paint it myself.

 

[pc1p]

I'm doing a complete colour change (original Bright Silver to grey) except for under the hood with no edge blending of any primer or paint. I've done it this way before without any problems. I do have a few areas where I'l be going down to bare metal and the whole panel will be primed before painting.

Good to hear!

In my experience, we only used Scotch Brite pads in two scenarios: small area scuffing for prep (usually after rust or sheet metal repair) OR for in-between scuffs of primer or base-color coats that have cured for too long (usually MFG's say if a layer has sat for more than 7 days, it needs to be scuffed). However, we always went with MFG recommendations for prep requirements for full panels. This was mainly to ensure color and texture match as well as give good edge adhesion.

We never did a color change without full prime coat - post up your results when you're done, I'm curious to see how well it comes out. I do not envy you spraying silver pearl

 

[PCO6]

Good to hear!

In my experience, we only used Scotch Brite pads in two scenarios: small area scuffing for prep (usually after rust or sheet metal repair) OR for in-between scuffs of primer or base-color coats that have cured for too long (usually MFG's say if a layer has sat for more than 7 days, it needs to be scuffed). However, we always went with MFG recommendations for prep requirements for full panels. This was mainly to ensure color and texture match as well as give good edge adhesion.

We never did a color change without full prime coat - post up your results when you're done, I'm curious to see how well it comes out. I do not envy you spraying silver pearl

Lots to do yet but it's getting there ...

 

[steelhd]

I had planned to sand the half doors down, prime, paint etc. I was talking with a friend and he asked “why not just paint over what is ...

No need to guess, wonder, ask strangers on the internet, or have a medium consult the spirits of long dead paint chemists. Go to the manufacturers website, read their instructions, then follow them exactly. If you have questions about the the manufacturers procedure for the product you bought then ask questions. I'll get you started ...
https://www.automotivetouchup.com/spray-paint-directions.htm

 

[Dunkut88TJ]

No need to guess, wonder, ask strangers on the internet, or have a medium consult the spirits of long dead paint chemists. Go to the manufacturers website, read their instructions, then follow them exactly. If you have questions about the the manufacturers procedure for the product you bought then ask questions. I'll get you started ...
https://www.automotivetouchup.com/spray-paint-directions.htm

thanks

 

[Dunkut88TJ]

Finished removing adhesive from a door seal today, it might as well have been welded on. Got the paint and did a test run, pretty pleased with the results for PSB in a rattle can. We will know how it turns out by tomorrow night!

 

[DETOUR]

We decided to roll-on a heavy coat of box-liner
• I assume we should still rough up / sand the original paint
• I haven’t checked with the application info of the product ( haven’t decided what brand box liner coat either)

Thx for everyone’s input in advance %

 

[TJ4ord]

Top of the morning folks! I had a question regarding painting and wanted to ask the gurus here. I believe I know the answer but figured it worth a shot. It says my paint from automotivetouchup.com will finally arrive today - 4 weeks. I had planned to sand the half doors down, prime, paint etc. I was talking with a friend and he asked “why not just paint over what is there?” So I ask you guys why not? I would assume sanding it to bare metal promotes a far better result but what if I didn’t sand down the existing clear coat and paint? Would the new stuff flake off? Truly a question of curiosity from someone that had never taken on this task, please me gently

Hey Dunkut88TJ,

I know this is an old thread but I'm doing the exact same thing to my '04 Rubicon. I found a really nice set of half doors but they are the burnt orange. I had the same questions. I ordered Flame Red PR4 from automotivetouchup. What did you end up doing about sanding down the existing paint? How did they turn out? Thanks.

 

[BlueC]

Hey Dunkut88TJ,

I know this is an old thread but I'm doing the exact same thing to my '04 Rubicon. I found a really nice set of half doors but they are the burnt orange. I had the same questions. I ordered Flame Red PR4 from automotivetouchup. What did you end up doing about sanding down the existing paint? How did they turn out? Thanks.

Painting over the orange with red will not be that much of a risk, not like painting red over blue or something. It's best to use a sealer, but in your case, you could get away without it. As for sanding the paint, that is an "it depends" situation. If the paint it's flaking or losing adhesion in any area, that has to be removed first. Do not attempt to paint over questionable material. Body work needed? What is your tolerance for good vs ok finished product? If everything looks good, and you just need a color change, a scuff-n-shoot will work. So to answer your question, it depends.

 

[TJ4ord]

Painting over the orange with red will not be that much of a risk, not like painting red over blue or something. It's best to use a sealer, but in your case, you could get away without it. As for sanding the paint, that is an "it depends" situation. If the paint it's flaking or losing adhesion in any area, that has to be removed first. Do not attempt to paint over questionable material. Body work needed? What is your tolerance for good vs ok finished product? If everything looks good, and you just need a color change, a scuff-n-shoot will work. So to answer your question, it depends.

The doors are in really nice shape, a minor surface scratch or two but no flaking, peeling. I just assumed that I had to at least sand thru the existing clear coat to get good adhesion. I want to do it right as I'm in no hurry and pretty particular. I'm only using a sanding block because the half doors are so small and didn't think I needed to purchase a DA sander for just this job. Any suggestions are greatly appreciated. Thanks.

 

[JMT]

The doors are in really nice shape, a minor surface scratch or two but no flaking, peeling. I just assumed that I had to at least sand thru the existing clear coat to get good adhesion. I want to do it right as I'm in no hurry and pretty particular. I'm only using a sanding block because the half doors are so small and didn't think I needed to purchase a DA sander for just this job. Any suggestions are greatly appreciated. Thanks.

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All you need to do is scuff the surface with 400 grit on a DA sander, then top coat and 2K clear.

I would not use a sanding block. Uneven pressure could cause the finished product to appear wavy.

I would also check that color on something else before doing the doors. I’ve had both good and bad results from purchasing according to the paint code. I’ve had far better results from an automotive paint supply matching the actual paint on my Jeep.

 

[TJ4ord]

All you need to do is scuff the surface with 400 grit on a DA sander, then top coat and 2K clear.

I would not use a sanding block. Uneven pressure could cause the finished product to appear wavy.

I would also check that color on something else before doing the doors. I’ve had both good and bad results from purchasing according to the paint code. I’ve had far better results from an automotive paint supply matching the actual paint on my Jeep.

It's a shame to have to paint them since they look so good! Thanks man!

 

[JMT]

It's a shame to have to paint them since they look so good! Thanks man!

Yeah, too bad the doors are Impact Orange and you need Flame Red!

You’ll do pretty good. If it doesn’t turn out you’ll do better the next time. I’ve done half doors, corner armor, tailgate armor, and portions of front fenders. I started with cans and moved to spray guns.

 

[tworley]

...and 2K clear.

In my experience, this has been the hardest part. 2k clear is not available anywhere locally in my area, and the good stuff online is pretty darned expensive. But 2k is the best one to use.

 

[BlueC]

As mentioned, those doors look to be in good condition. I think a scuff-n-shoot will be fine. I highly recommend painting a test card the same as you will these doors (primer & paint) before spraying anything, just so you can see if the color matches or not. Some reds have a tendency to fade without much notice until a new red is laid down, or maybe the paint supplier messed up the batch. A test card will show that without much cost.

@chili_pepper is/was a body guy. Maybe he'll chime in.

 

[chili_pepper]

@chili_pepper is/was a body guy. Maybe he'll chime in.

"Was" many moons ago, but the process is still applicable.

The doors are in really nice shape, a minor surface scratch or two but no flaking, peeling.

They do appear to be in excellent condition, damage and paint-wise. Not sure what you gave for them but a solid find for what they are.

I just assumed that I had to at least sand thru the existing clear coat to get good adhesion.

I would NOT do this unless there is a good reason to, and I can't see one from here (but I'm not there). Unless there's an issue with the existing finish (adhesion issues, finish build-up, rust under finish, poor application, etc.) there is no need to cut through it, though you do need to prep it.

5 minute refinishing list:

• Before you do much of anything, I'd hang them on your Jeep and check the alignment, now is the time to make adjustments. I'd get the hinges properly located on both doors now. Edit: I note there are no hinges on the doors and there IS paint where the hinges would be, I suspect these have already been refinished or were replacement doors, Chrysler did not paint under the hinges at the factory (cuz they're cheap bastards!)
• Before doing any sanding, wash the doors (with original Dawn) and let them dry, then give them a once over with wax and grease remover (prepsol). You are aiming to remove any finish products applied previously as well as any general shit that's accumulated on the existing paint surface. If you sand before removing the foreign material, you'll be sanding it into the surface which can cause issues with the final results.
• Strip the doors of all weather strip, door cards and external hardware (door handle, lock cylinder).
• Once stripped, clean any areas previously covered with the prepsol.
• After that decide what you want to do with the scratches, if they aren't through to metal, I'd probably use a catalyzed glazing putty and/or 2k filling primer to fix.
• Post any sanding for scratch repairs (no coarser than 320), I'd probably work from 400 to 800 (at least 600) on the existing clear and primered repair areas, preferably by machine where possible (soft pad sand jambs). Edit: When moving through sanding grits, I tend to jump no more than 80-100 grit at a time up to 600. You risk not eliminating the previous scratches if you jump too far in grit.
• Prep for paint (prepsol, blow, mask, tack)
• Shoot a 2k epoxy as a sealer followed by color and 2k clear, full coverage.

The noted 2k materials would be in rattle can form, it is possible to get a really nice job from these products (I use SprayMAX). Perfect world you'd be shooting with a good filtered air system and an HVLP gun...if you have that option, I'd go for it and good on ya.

 

[BlueC]

If that sounds like too much, there's also the option of selling your doors and finding a good set of red doors.

 

[chili_pepper]

If that sounds like too much

It really isn't that bad....but there is a reason some wait until they can find doors the correct color.

 

[TJ4ord]

"Was" many moons ago, but the process is still applicable.



They do appear to be in excellent condition, damage and paint-wise. Not sure what you gave for them but a solid find for what they are.



I would NOT do this unless there is a good reason to, and I can't see one from here (but I'm not there). Unless there's an issue with the existing finish (adhesion issues, finish build-up, rust under finish, poor application, etc.) there is no need to cut through it, though you do need to prep it.

5 minute refinishing list:

• Before you do much of anything, I'd hang them on your Jeep and check the alignment, now is the time to make adjustments. I'd get the hinges properly located on both doors now. Edit: I note there are no hinges on the doors and there IS paint where the hinges would be, I suspect these have already been refinished or were replacement doors, Chrysler did not paint under the hinges at the factory (cuz they're cheap bastards!)
• Before doing any sanding, wash the doors (with original Dawn) and let them dry, then give them a once over with wax and grease remover (prepsol). You are aiming to remove any finish products applied previously as well as any general shit that's accumulated on the existing paint surface. If you sand before removing the foreign material, you'll be sanding it into the finish which can cause issues with the final results.
• Strip the doors of all weather strip, door cards and external hardware (door handle, lock cylinder).
• Once stripped, clean any areas previously covered with the prepsol.
• After that decide what you want to do with the scratches, if they aren't through to metal, I'd probably use a catalyzed glazing putty and/or 2k filling primer to fix.
• Post any sanding for scratch repairs (no coarser than 320), I'd probably work from 400 to 800 (at least 600) on the existing clear and primered repair areas, preferably by machine where possible (soft pad sand jambs). Edit: When moving through sanding grits, I tend to jump no more than 80-100 grit at a time up to 600. You risk not eliminating the previous scratches if you jump too far in grit.
• Prep for paint (prepsol, blow, mask, tack)
• Shoot a 2k epoxy as a sealer followed by color and 2k clear, full coverage.

The noted 2k materials would be in rattle can form, it is possible to get a really nice job from these products (I use SprayMAX). Perfect world you'd be shooting with a good filtered air system and an HVLP gun...if you have that option, I'd go for it and good on ya.