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Scuffing truck bed for paint.

#1
I just took on a job painting a truck bed for a gmc dually. The guy bought a brand new bed off a guy that has never been on a truck. The new bed is red the truck it’s going on is black.
So my question is should I just scuff the red paint, spray the black base and clear? Or should I scuff, seal, and then paint? What would a shop do in this situation?
I don’t care to scuff and seal but don’t want to add extra buildup and work if not necessary.
Also what grit would be recommended for scuffing the bed prior to paint?
Thanks.
 
#3
If it wasn’t black over red I wouldn’t even consider sealing. Rock chips showing red underneath is the only reason I was considering sealing.
I think scuffed clear is a very good foundation for base.
 
#4
I have a truck bed coming with the same situation.
I like to seal it with a reduced coat of epoxy, if doing epoxy you can first scuff the
new paint with a red scuff pad because the epoxy will fill the scratches from the red.
The red one makes it much easier and faster than using a gray one which
is what you would use if you were going to paint over good paint.
The epoxy provides a much better adhesion against chipping in the future.
If the new bed paint has much peel to it, I'd rather sand it all with 600 grit to level first.
 
#6
All good advice above. I have always sealed under black because I was told to by a paint rep probably 30+ years ago, and can't remember the exact reason why. I sand with 600 and a gray scuff pad before base, but before sealer red pad is fine, especially under a solid color. I would sand it real quick with 400-600, though it is not a necessity, then red pad thoroughly, seal then base. Sealer is cheaper than base, and will eliminate any chance of coverage problems, and no red rock chips as you described.
 
#7
If you sand with 600 do you still scuff with the red pad after the 600?
No, I usually go to paint after sanding with 600.
If I am going to prime first, I would have sanded with something more coarse like 180 to 220.
It's just faster and easier with the coarser grits and they get it straighter.
But on original paint that's in good shape, I sand with 600 and then paint.
It's only when I want better adhesion, like bumpers because of road rash abuse, will
I prime with epoxy first. Even then I like to scuff the epoxy with a gray pad first even
though you don't need to.
 
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#8
Thanks everyone for the advice. The guy brought me the bed this morning. Wouldn’t you know he dented it loading it on his trailer. So I got a dent to fix now.
After I get the dent fixed, I think I’ll sand the whole bed with 600, seal, and paint.
 
#9
Ok got the bed all scuffed with 600 wet and used red scotchbrite pad in hard to get areas.
Plan on sealing tomorrow and painting.
The bed is going to be black. Will sealer fill the 600 grit scratches ok for black base?
 
#11
Well I got the bed sealed and everything was good. Layed down the base and it came out really grainy and rough. It is Wanda black base. I don’t know what I did wrong. So I’m planning on sanding the base smooth and trying again
Would 1000 grit wet be ok to smooth out the base before reapplying more base?
 
#12
The tech sheet states for denibbing to use 600-1000.

What gun and settings did you use, what reducer, did you reduce 2:1, and what was the temp/weather when you sprayed?
 
#13
I bought it premixed at the paint store. First time I’ve used it so it was only $4 extra to buy it ready to spray.
Was 73 in the garage when I sprayed. Used my lph400 with purple aircap.
 
#14
I bought it premixed at the paint store. First time I’ve used it so it was only $4 extra to buy it ready to spray.
Was 73 in the garage when I sprayed. Used my lph400 with purple aircap.
The purple cap is probably the worse if you’re spraying black paint, it pretty much dusts the paint on. Do you have the orange or silver cap?
 
#16
The silver cap will lay that black base down nice. I would question what they did to make it ready to spray before spraying any more, and test it on a test panel of some kind before spraying it on the vehicle again.
 
#17
I questioned the guy about the sprayable base. He said they just go ahead and add the proper reduced when mixing the paint. Said it saves people from buying a gallon of reducer just to spray a small amount of paint.
I have plenty of reducer, but since it was my first time spraying this brand and was going to spray it the next day I went ahead and let the guy add the proper reducer.
 
#19
The biggest change to settings is turning the pressure down and narrowing the fan until the pattern isn't split (heavy at top and bottom). Check it on a piece of paper. For me it usually ends up 20-23 psi at the gun, 2 1/2 - 3 turns out on fluid, fan turned in 10-15% from fully open. Which "proper" reducer did he use. Jobbers sell paint for a living, so I bet it wasn't a top of the line reducer, and it makes a bigger difference than most people (including jobbers) think.
 
#20
On my blue Wanda base I've used the following which lines up with texasking. Air 23 psi on the gun regulator, 125 at the wall. Fluid closed then out 2.5 turns. Fan out all the way and then in 1 turn.

One thing to double check always is the air knob at the bottom of the gun, make sure it is out all the way. Also make sure you don't have any type of strainer in your cup.

I use SPI reducer.
 
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