1st time wet sanding & uhh... did i mess up sanding or painting?

[chato de shamrock]

I'm working on my 8th model and this is my first time wet sanding the body to get the mirror shine. Previously I've only used Tamiya compounds but the shine I got was nothing close to what some of you guys achieve with your models, so I wanted to try something different this time and also apply decals before applying the clear coat. I've been reading around trying to get as much information I can about how to do all this the right way. Tonight I wet sanded, rubbed compounds, and polished with Tamiya wax. However, paint came off almost immediately when I started to wet sand the body.


I painted the model well over two months ago. I did not prep-sand the body so the paint holds to the plastic, and this particular model was not primered. Instead, I sprayed Tamiya Pink (TS-25) as a primer followed by Tamiya Italian Red (TS-8). Tonight I filled a container with water and a drop of detergent. Then I wet the abrasive papers and model. I started with 3200 grit paper. I wrapped the abrasive paper on my finger and rested it on the model. Then I slowly and gently glided it over the body. I did it so soft (with a bit of fear I'd sand right down to the pink) you'd think I was handling a 2 day old baby. Some of the paint came off almost immediatly. I rubbed in a circular motion moving at all times along the model and making sure I did not stay in one spot. Yet the paint came off in some areas as soon as the paper just went over that area of the model. I was thinking, "NO! I just started sanding and havent even used the other abrasives." At this point I knew I screwed it, and it sucked cause I had just started. Any of you that have built R34's know the edges on the car's roof that you have to watch out not to sand too much paint off. Well that, the door handles, around the rear lights, fender areas, and front-top of the doors next to the windshields is where the paint came off. Funny thing is that I moved on with 3600, 4000, 6000, 8000, and 12000 paper and not much more paint came off those areas.

I still when ahead and applied some Tamiya Fine and Finish compounds, but the paint was dull after the compounds were rubbed on and dried. Then, I applied Tamiya wax and a nice shine came out after rubbing it for a few minutes. Finally, I applied a spray wax made by The Treatment and rubbed for a few more minutes. I achieved a nice mirror shine but still not close to what some of you guys can do with your models like, for example, the AF Model of the Year or the 2nd and 3rd place runners up. Its more like a "just washed car" look rather than the "out of the dealership gallery" look

While i wet sanded paint came off. When I dumped the water I noticed a ring the paint left around the container. When I dried the model I saw paint on the towel. When I rubbed compound I noticed paint came off more than with my previous models. The paint still kept coming off when I waxed it. Is this normal?

I think im going to buy another can and spray the model again. What can I do to minimize the chances of paint coming off again? Should I skip the 3200 grit paper? Instuctions provided by Detail Master say not to skip any abrasives. By the way, my paint job came out smooth so was 3200 grit too rough on the paint? What can I do to make the slight glass like finish I got even shinnier?

When things are ready I will apply the carbon decals on the trunk and hood followed by the (Mr. Clear) clear coat. Do you guys wet sand again after the clear coat has been applied and cured or do you just compound and/or wax?

All in all, sanding the body did give this model a glossier, shinnier, glass look than my previous methods of primer, paint, compound, clear, compound, wax.

Pardon for the poor quality of this picture. It should show a glossy hood but it was taken with a cell phone camera, and thanks to everyone that took the time to contribute or just simply read my thread.

[Vyacheslav]

well first u need primer, then I would also recommend having more coats on your model knowing that some paint will come off when you polish it. Maybe 3200 was a bit too much to start with, it is fairly easy to rip the paint off with it, maybe try starting off with 6000.

[bvia]

Next time try polishing the clear coat, not the color coat. also start with a higher abrasive (higher number which would be less coarse). All you are trying to do when wet sanding a model is to level the surface. The polishing does the actual polishing of the paint.

hth,
Bill

[MPWR]

First of all, skip the 3200. Always. It's much too abrasive to be used on paint. 3600 is also very abrasive- usefull carefully only in cases of significant orangepeel. If I bother to sand paint at all, I usually start with 4000. I also usually end with 4000.

I've never used a sanding kit without burning through the paint somewhere. Sure, it's a great theory, but I've never found a paintjob (even hard automotive laquer) that will stand up to the full regime of grinding. For me there are better and easier ways to get a good shine.

Sanding kits were not designed for use on model paint. There are applications that they're perfect for- polishing plexiglass, for instance. But for hobby paint, most of us simply do not apply paint thick enough on car bodies to be safe to remove enough for a polishing kit to work. If you do, you risk filling in alot of body detail with paint.

I definately agree to polish the clearcoat, and leave the base color alone. If it doesn't have gross orangepeel, don't mess with it. And definately don't wax it or the like if you're still going to apply clear over it.

There is not one The Way to do 'mirror' finishes, no matter what Detail Master says. Each of us really develops our own technique, based on our own experinces with our own favorite materials. Lately, I've got one that really works for me- but it took alot of playing to get a good feel for what I'm using.



This body was painted with auto laquer, overcoated with many thin layers of very reduced clearcoat sprayed at the lowest pressure possible through a gravity feed airbrush. It was then polished with Tamiya coarse, and then McGuire's ScratchX. Then waxed with carnuba. A polish kit never touched it.

But there are many different ways of getting there- and practice and experince are really the only common elements. I've found though that polishing kits are one of the most difficult and frustrating ways of going at it.

[bhop73]

I agree with what these guys are saying. You need the primer to have a "bite" for the paint, so skipping that was strike one. 3200 was definitely too much. I generally only use polishing kits if I have to get dust out of my paint, and even then, I tend to use nothing lower than 4000, otherwise, I just use polishing compound and wax, and that's over the clear coat. Assuming your paint is applied correctly, the compound should be abrasive enough to give you a nice shine. Just takes some patience.

[drunken monkey]

Not sure I agree with the primer being the thing the paint bites onto.
Now it could just be me using the wrong primer of even not cleaning up my sanded primer properly but everytime I drop a model or drop something onto a model, the paint seems to chip off to the primer.

One thing though, primer does allow me to fix the body surface and smooth it down as well as I can (yes that means you have to sand down your primer as well which can take just as much time as polishing paint) which does help in the long run to allow me to lay down smooth/flat coat of paint.

[tigeraid]

Agreed on the clearcoat, for sure. And if you're NOT using clearcoat (some people don't, over solid colours--I don't, sometimes, and I know Primera Man doesn't always use it either) then make doubly sure you have lots of colour coats before you wet sand.

You'll ALWAYS rub through the paint somewhere on a model during polishing--usually on raised edges or door handles--but to have it come off the way you described is really weird.

As far as the wax btw, you WILL still have some paint come off on the cloth with wax, just tiny amounts, because it's the left over on the surface after polishing.

And also, this is just a prefferential thing, but I'd suggest sanding always in straight directions, not circular; go one direction with your first grit, then change direction with the next grit, and so on. Circular sanding motion leaves fine swirl marks in many cases.

[bhop73]

Originally Posted by drunken monkey

Not sure I agree with the primer being the thing the paint bites onto.
Now it could just be me using the wrong primer of even not cleaning up my sanded primer properly but everytime I drop a model or drop something onto a model, the paint seems to chip off to the primer.

One thing though, primer does allow me to fix the body surface and smooth it down as well as I can (yes that means you have to sand down your primer as well which can take just as much time as polishing paint) which does help in the long run to allow me to lay down smooth/flat coat of paint.

I'm curious what your primer/paint combo is? I have found that if I get a chip, it always goes all the way through, primer and all.. I use Tamiya Grey Primer and Tamiya paints generally, although, sometimes I use Finisher's paint (as of this past month)

[drunken monkey]

I've been using halford's (UK auto store) automotive primer (grey base then usually a white top).
Body is filled/trimmed/tweaked then sanded all over with 600 grit (3M) sandpaper (1800 micro mesh equivilant).
Then it's primer coat one (grey).
Sand down to fix the smallest scratches.
Primer coat 2 (grey).
Sand down to uniform slick smoothness (y'know, when it feels oily under water).
Then it's white primer which I sand down after every coat until uniform and smooooth.
Paint has always been tamiya ts sprays from the can.

I've recently switched to halfords primer for plastic which might make a difference.
I'll drop something on it and let you know how it goes....

incidentally, the sun is coming back out around my parts of the world so i'll have er... a few wips for the ferrari group build soon, not to mention that I've got two weeks off work to play around with.

[Hawk312]

Originally Posted by chato de shamrock

I achieved a nice mirror shine but still not close to what some of you guys can do with your models like, for example, the AF Model of the Year or the 2nd and 3rd place runners up. Its more like a "just washed car" look rather than the "out of the dealership gallery" look

Since you mentioned it, now I feel obligated to respond.

I agree with most of what was said. However, I have to disagree with alot of what is being said about abrasives and wet-sanding. You should determine the abrasive you will use by:

1. the depth of orange peel
2. the number of coats of paint that have been applied.
3. your level of experience
4. your willingness to repaint

The more you have of the above, the more abrasive you can go. For me, I always start with nothing higher than 2000. On the Camaro you mentioned I started with 1500. I did have probably 10-12 coats of clear on it, but would`ve done the same with 5-6 coats. In fact, I`ve found that using a more abrasive sandpaper actually reduces the chance for burning through sometimes, as less time is spent actually sanding because the large areas "flatten" at a faster rate leaving fewer time spent over the edges. After the 1500, I used a rather abrasive cut compound (Meguires number 1 medium cut or 3M extra cut) followed by fine cut compounds(3m swirl and haze remover, tamiya "fine", 3M fine cut) followed by polishing compounds (Tamiya Finish) followed by polish.




Where you really get the shine is the middle compounds IMO. The longer you can spend with these, the more shine you will get.
Back to your problem....
Are you sure you went through the paint? Are you seeing the pink undercoat or the plastic underneather, or is it just "dull".
If you did go through, I think your main problem is just not enough paint. Unless you are a master spray painter like p-man (who is known to cover a car with less than half a can and still be able to rub it out), us more average painters should probably get atleast 4-5 thin coats on a model to ensure we don`t burn through. If I were to do less than that, it is a good chance I`ll have to repaint or settle for an "OK" finish. The more paint you get on (without losing detail mind you), the more you can rub, and the shinier it will be!

[chato de shamrock]

Originally Posted by drunken monkey

Not sure I agree with the primer being the thing the paint bites onto.
Now it could just be me using the wrong primer of even not cleaning up my sanded primer properly but everytime I drop a model or drop something onto a model, the paint seems to chip off to the primer.

I've had a similar problem happen to me last year. I washed some resin seats and primered them the very next day. Once I applied two or three coats (forgot exactly how many) I followed with the paint. After i'm guessing close to two weeks had gone by I started to futz with them and the cars interior. Then all of a sudden a piece of paint with primer falls off. I posted my experience in a thread and was told I didnt wash the resin well enough.

By the way, I used tamiya primer and paint on the seats. I've been warned to stick with same or similar products because some paints dont play well with primers made by other companies. I've been sticking with tamiya lately but buy testors and model masters spray cans only if I have to. I've noticed when I use Tamiya I get a very nice smooth job. On the other hand, when I use testors or M.M. I get a rough orange peel and the paint goes all over the place. I stay clear of those cans because of their infamous nozzels and I paint outside my apartment. I dont want the owner get on my case about paint getting on the floor.

I average about 7 coats of Tamiya's spray paint before I run out, and thats the number of coats this model had. The paint stripped down to the pink paint in some areas and the pink was starting to show in others.

Originally Posted by tigeraid

As far as the wax btw, you WILL still have some paint come off on the cloth with wax, just tiny amounts, because it's the left over on the surface after polishing.

I've always had paint come off when i wax. They were small amount. Yesterday however seemed to be quite more than usual. At least thats what I thought.

Im going to try placing the decals under the clear coat with this model so should I make sure i apply plenty of clear to make sure I dont damage the decals when I polish it? I've read and also been told that Mr. Hobby clear is friendlier when dealing with decals so im thinking of trying that instead of tamiya clear.

[chato de shamrock]

Ive been trying to get a finish like that of your Porshe MPWR. Notice how the lines from your work mat are clearly visible. Best i've been able to get is a shadow type of shine. I got a tiny shine on the hood of this model, unfortunatly my cellphone doesnt have a good quality camera. I can see a color shadow. Now Hawk's Camaro, I seriously thought for a second that it was a diecast when I first saw it. Who's house is that I see reflecting on the driver side door, the neighbor across the street? Man, seriously, thats a perfect finish. How do you get that shine from a plastic model?

[drunken monkey]

Originally Posted by chato de shamrock

I've had a similar problem happen to me last year. I washed some resin seats and primered them the very next day. Once I applied two or three coats (forgot exactly how many) I followed with the paint. After i'm guessing close to two weeks had gone by I started to futz with them and the cars interior. Then all of a sudden a piece of paint with primer falls off.

not sure if you've understood me properly; i've never had paint just fall off with primer.
My experience is that when I drop something onto a model or drop the model itself and something breaks, the paint tends to chip off the primer; leaving plastic WITH primer.
i.e the primer is rock solid on the plastic.

a couple of shots of my black xk-ss, one of the few things that i actually finished....



the paint surface isn't 100% scratch free but the paint is nice and flat, hence the clear and not too warped reflection.

[Hawk312]

Originally Posted by chato de shamrock

Now Hawk's Camaro, I seriously thought for a second that it was a diecast when I first saw it.

A die cast??! That`s an insult in these parts! Just kidding. Glad you think it looks good.

Originally Posted by chato de shamrock

Who's house is that I see reflecting on the driver side door, the neighbor across the street? Man, seriously, thats a perfect finish. How do you get that shine from a plastic model?

Just keep rubbing, and rubbing, polishing and polishing. You are looking at atleast 8-10 hours of work on the Camaro. You`ll also want to make sure all the orange peel has been sanded away (another good reason to use more than enough coats of paint). Also try to sand in long strokes and try not to keep in one area or use circular motions too much. This keeps the surface as level as possible, and keeps it from getting "wavy".