(wet) sand before applying clear coat?

[Bastiaan 180]

Hi everyone,

Maybe this is a stupid question but I can’t get a clear answer while searching. Do you (wet) sand the final coat of paint before applying clear coat (ts-13)? Thanks! 

[CoolHands 648]

I didn’t when I did mine, but you can. You can flat it with very fine grade paper eg 1500 then apply clear coat.

[Bastiaan 180]

Thanks CoolHands! And what would be different in the result, sanding or not before applying clear coat?

[waterbok 1282]

You may have tiny imperfections, dust etc.

If you just clear coat over that, those may be more visible

[Bastiaan 180]

Ok thanks! Will try without sanding and see how it works out. 

[Wetman 417]

Silly question but can you put the decals on before you do the final laquer coat? Has anyone tried it?

[lucasan 28]

I have seen a video recently where a guy does a couple of layers of clear over his decals. I'm not sure if it's the same for stickers, but I imagine that being a lot thicker, you could do more than a few layers to get an even coat over the stickers to where you couldn't feel them to the touch. someone else please chime in though.

 

[CoolHands 648]

I lacquered over my Clod stickers/decals (what’s the difference?)

[lucasan 28]

@CoolHands I think the difference is that if you put enough clear coat on the body after stickers/decals, that they look more like they're part of the paint job. This finish is very desirable in the modeling community and in competitions, but I don't know about the rc world.

[Falcon#5 591]

13 hours ago, CoolHands said:

I lacquered over my Clod stickers/decals (what’s the difference?)

Waterslide decals are quite thin and easier to clear coat.

Self adhesive stickers are thicker and will have an obvious edge.

[Wetman 417]

15 hours ago, CoolHands said:

I lacquered over my Clod stickers/decals (what’s the difference?)

That looks the part. I was wondering if the clear would be too thick or react with the vinyl but that looks ok

[mtbkym01 3674]

I always clear coat over the stickers/decals on hard bodies, seals them to prevent lifting (atleast I haven’t had any lift)

[Apexape 13]

You only need to sand base coat before clear if you did not apply the clear within the base coat flash time window. If you let the base coat dry too long it’ll develop a seal so to say over it and the clear coat won’t adhere to it chemically like it’s supposed to. 

[mtbkym01 3674]

9 hours ago, Apexape said:

You only need to sand base coat before clear if you did not apply the clear within the base coat flash time window. If you let the base coat dry too long it’ll develop a seal so to say over it and the clear coat won’t adhere to it chemically like it’s supposed to. 

How long would this usually take? Out of curiosity

[Falcon#5 591]

On 5/3/2020 at 1:57 PM, mtbkym01 said:

How long would this usually take? Out of curiosity

Would be the same time between coats of colour if your using a compatible clear.

[Nicadraus 5721]

Yes wet sanding is a must if your paint has the "orange peel" effect. Your sand paper grit will depend on how deep the effect is and how thick your base coat is. But doing a 1500 to 2500 grit is safe. Use the 1500 first, then the "used" 1500. Refine that with the 2000 then 2500 before buffing.

Here's my Pajero after wet sanding the cured top coat and before 3-step buffing

 

[Nicadraus 5721]

On 5/3/2020 at 4:09 AM, Apexape said:

You only need to sand base coat before clear if you did not apply the clear within the base coat flash time window. If you let the base coat dry too long it’ll develop a seal so to say over it and the clear coat won’t adhere to it chemically like it’s supposed to. 

This will depend on what paint you use. Thinner based, water based, acrylic, polyurethane, etc. Each type has different methods in preparation, painting process and post painting process. I know this because I paint and detail from diecast (plastic and metal) models, to turntables, audio gear, DJ gear, car parts and panels using different types of paint. Wet sanding the top coat is still better and gives smooth results at the end before going over to detailing (buffing, polishing, waxing/ceramic sealing)

[Apexape 13]

On 5/4/2020 at 11:01 PM, Nicadraus said:

This will depend on what paint you use. Thinner based, water based, acrylic, polyurethane, etc. Each type has different methods in preparation, painting process and post painting process. I know this because I paint and detail from diecast (plastic and metal) models, to turntables, audio gear, DJ gear, car parts and panels using different types of paint. Wet sanding the top coat is still better and gives smooth results at the end before going over to detailing (buffing, polishing, waxing/ceramic sealing)

we are not talking about the same thing. I am referring to sanding base coat (color coat) before clear coat. The only reason to sand base coat is if you let it flash out for too long in order for clear coat to properly adhere chemically or because you messed up spraying your base coat and sprayed it too dry or got tons of dirt in it or visible sanding scratches. Either way you would apply more basecoat over before you clear coat because the areas you fixed by sanding will show especially in metallics where the flake orientation will be uneven if you don’t reapply basecoat. 
 

now when it comes to wet sanding clear coat before buffing and polishing yes you are right. It gives it a smoother appearance but at the cost of durability. On small scale stuff it’s not a big deal but on a full size car it is. When you wet sand you are removing practically half of the clear coat before buffing and polishing just to get that glass like finish. There is a reason cars from the factory come with orange peel. It’s for durability. 
 

as a professional automotive refinisher we are trained to attempt to imitate the way the cars were sprayed in the factory. If you want a durable smooth glass finish your gonna have to apply double the amount of clear coat just to leave enough after sanding for buff and polish. 
 

now this is all talk with regards to pro materials and basecoat/clear coat systems. Most hobbyist I’d say use rattle cans. The trick with those is practice distance from object and speed of each pass. Most every clear coat nowadays are of good thickness and have good flow properties. You want your first coat to be a medium wet coat. If it looks only a little dry it’s fine, the next slightly heavier coat will fix it. Don’t try and get rid of dry spots before the clear has flowed out because that’s how you get runs. 

[Apexape 13]

On 5/3/2020 at 2:57 PM, mtbkym01 said:

How long would this usually take? Out of curiosity

Depends on the paint system. It would say in the Material Data Sheet (MDS) or on the can if using rattle cans. It can range from a few hours to 24 hours. 

[Nicadraus 5721]

22 hours ago, Apexape said:

we are not talking about the same thing. I am referring to sanding base coat (color coat) before clear coat. The only reason to sand base coat is if you let it flash out for too long in order for clear coat to properly adhere chemically or because you messed up spraying your base coat and sprayed it too dry or got tons of dirt in it or visible sanding scratches. Either way you would apply more basecoat over before you clear coat because the areas you fixed by sanding will show especially in metallics where the flake orientation will be uneven if you don’t reapply basecoat. 
 

now when it comes to wet sanding clear coat before buffing and polishing yes you are right. It gives it a smoother appearance but at the cost of durability. On small scale stuff it’s not a big deal but on a full size car it is. When you wet sand you are removing practically half of the clear coat before buffing and polishing just to get that glass like finish. There is a reason cars from the factory come with orange peel. It’s for durability. 

As I mentioned, it depends on the type of paint you use and method. Acrylic is mixed and applied differently from urethane and different from waterborne (water based). Urethane for example, the catalyst is very important because it bonds the paint even better making it stronger. Number of layers/coast will also depend on the panel's size and area. Of course, the top coat will be lessened every time sanding is made but this is only necessary for paint correction. So proper paint volume mixture, layering and number of coats also vary on the process which the correction will depend if needed or not. Also paint mix volume and thickness will vary on the spray gun/air brush used. 

This is coming from a person who has experience in both painting (hobby and professional) and detailing (finishing included).