Question on painting

[zeroxs650]

I went to YouTube to try and get my question answered and did not find a definitive answer, I applied the final coat to several pcs of the bike, do I sand it before I clear coat? I have applied several coats and have sanded between coats and would think you would NOT sand before clearing. Anyone's help would be greatly appreciated.

 

[YamadudeXS650C]

I would not sand the final base coat if it is metallic paint.
Otherwise, you are OK.
Is this acrylic lacquer you are using?

 

[zeroxs650]

I am using Rust-oleum auto primer and enamel spray paint.

 

[YamadudeXS650C]

Cool. Keep in mind that if your clear coat is also enamel, it will be vulnerable to gasoline and ethanol (like on tanks). Many folks are using SprayMax for a really tough clear coat. Its $20 a large can. You would have to check with the autobody seller to see if it will go with the enamel you are using.

 

[warrenlevihursh]

Do not sand before your clear. I would spend a few extra dollars and buy the spray max 2K in a can. Its a 2 part and will hold up to gasoline spills. Regular spray clear is pretty much a waste of time. Believe me, I know! Make sure to wear a mask with the 2K. It's like $22 online.

You can wet sand and buff the clear when you are done to make it like glass. I would use at least 1500 paper. Good luck.

 

[Max Midnight]

Do not sand before your clear.You can wet sand and buff the clear when you are done to make it like glass. I would use at least 1500 paper. Good luck.

Why do you say don't sand?
I have always flatted solid colours before applying the next to a) Show any high or low spots b) remove any small dirt nibs and c) to provide a key for the next coat.
At the very least I would use a Scotch pad to give a key.

Once you have a clearcoat that you are happy with and if you want the best shine you can get then use Micro Mesh cloth.
They start at 1500 grit and go up to 12000 and the idea is that as you go up the series of cloths the scratches left from the previous cloth are removed.
By the time you get to the 12000 grit cloth you will have shine that is deeper than the Marians Trench

 

[YamadudeXS650C]

Why do you say don't sand?
I have always flatted solid colours before applying the next to a) Show any high or low spots b) remove any small dirt nibs and c) to provide a key for the next coat.
At the very least I would use a Scotch pad to give a key.

Once you have a clearcoat that you are happy with and if you want the best shine you can get then use Micro Mesh cloth.
They start at 1500 grit and go up to 12000 and the idea is that as you go up the series of cloths the scratches left from the previous cloth are removed.
By the time you get to the 12000 grit cloth you will have shine that is deeper than the Marians Trench

If you sand the final base coat of a metallic color, you might lose some of the depth. Much less likely with a flat color. If you have significant dust nibs, I agree that sanding would be helpful.

I am in agreement with the use of a good mask when using SprayMax; it is literally deadly. When I use it, I spray outdoors in a mild breeze. I got my carbon mask at NAPA Paint for about $15.

 

[warrenlevihursh]

Why do you say don't sand?
I have always flatted solid colours before applying the next to a) Show any high or low spots b) remove any small dirt nibs and c) to provide a key for the next coat.
At the very least I would use a Scotch pad to give a key.

You can sand between base coats, I wouldn't suggest sanding the final base before the clear, but it could be done. I asked my professional painting buddy this same question. He recommended having a good, unsanded last coat for the base before clear.

 

[mrtwowheel]

PAINTING TANKS !!!!!

I have made this mistake twice, finally I learned. After painting tanks with very good automotive paint I have had the paint develop hair line cracks as if someone had taken a sharp utility knife to them. This was caused by clogged vents in the fuel caps, the tanks expand and contract with the vapors of the gas and temperature changes, virgin paint doesn't do well with this, clean or replace the vented caps.

I've never used clear but all of the labels that I've read suggest applying over un-sanded base coats.

Scott

 

[zeroxs650]

Thanks for the input gents. I'll let you know how the side covers turn out. As for the fuel tank, I will try and the 2K clear coat for the tank.

 

[Iron_inc]

You can absolutely sand before clear and if you've already sprayed your base coat and it's dried for longer then 24 hours "cured" you need to sand the base coat . Its called color sanding. If you want o see what I've painted search for "fresh paint " on this forum also if you have any other qs shoot me a email Id be ore then happy to help

 

[T-Sox]

+1 to what Iron_Inc said.

As others have said, just be careful if it's a metallic paint. Go slow and easy and whatever you do don't go at it with sandpaper and your bare hands if you don't know what you're doing. Get a nice flexible backing pad for the paper so you don't sand finger grooves into your paint.

Good luck

 

[Max Midnight]

After painting tanks with very good automotive paint I have had the paint develop hair line cracks as if someone had taken a sharp utility knife to them. This was caused by clogged vents in the fuel caps, the tanks expand and contract with the vapors of the gas and temperature changes, virgin paint doesn't do well with this.

There are several points here that I would query.

• All metal expands with heat but I would like to know how much fuel vapour within a tank would add to this.
• I wouldn't expect a good paint that has been applied correctly to crack. Try pushing on (say) a cars bonnet to see how much it flexes.
• Paint it probably at its most flexible when first applied. It will harden as the solvents evaporate before it becomes stable.

Alternative suggestions to the above 'cracking' problem is a) Vapour from the fuel vented via the seal ad attacked the paint or b) It was applied too thick and the crazing appeared as it dried and contracted.
You only need to put sufficient paint on to cover the substrate. The only exception I make to this is with a primer coat that I know will need heavy flatting. Once done I then leave the part for at least a week to ensure all solvents have dispersed before flatting again (I use rattle cans). Subsequent coats are applied as thin as possible.