Painting and sanding question

[Maniac21]

Hey everybody my names austin and im 16 i have started building my second model car ever and need help on painting it. i went buckwild the first time spray can painting it and it look bad so i got some 91 alcohal and rubbed all the paint off then sanded it and soaked it in soapy water. now here my delima.

I have primer and flat black can and gloss. i dont know what to sand and when. i have 150 grit,280 grit,320 grit,400 grit and 600 grit. now do i primer it and let it dry for a day then sand with the 150 and then primer and do i with the 280 till i get to to 600 and then paint and sand the same and the gloss?

[jbwelda]

hmmm yes well this is going to be a long thread here i predict. whole books (well, magazine articles) have been written about painting and i personally count it as one of the most challenging parts of model building, as do many others, if that is any consolation.

now about your situation: you currently are going to paint a body that has been painted already and then stripped. if it has not been stripped perfectly or if there was any damage to the plastic on the body outside, and especially if you havent done any customizing or modifying to the body...my thought would be to go buy a new copy of the kit so you can start with a fresh clean body...its gonna be difficult enough already. if though you cant afford it (hey we all know how that is), or cant find another kit, or did a bunch of customizing to the body, then so be it but remember every imperfection is gonna show ultimately unless you correct it somehow.

now to the paint thing, first off i wouldnt bother with the flat black paint, i would go directly from the primer to the gloss black. if you havent done any body work to the body and are going to be happy with the surface you have, you probably dont even need the primer. black is one color that will pretty much cover anything.

that said, the normal sequence of painting would be to prime the car, check for flaws in the bodywork or surface that you need to fix, lightly sand the primer with a pretty high (fine) grit paper, usually with water (aka "wet sanding"), reprime until happy with the bodywork, then one more thin coat of primer over the entire body.

now when i say sand the body, im actually addressing your question about the grits. i am unsure about the grits you have there, typically i use about a 250 grit for really coarse work, about a 500 grit for more medium and about a 1000 - 1500 grit for finish sanding. but different papers have different ratings even though they are the same courseness...or something, i never figured out exactly what was going on there. you also need paper that is water resistant because youre going to be using water to sand with, as lubrication and a cleansing and clearing medium.

the idea of using different grits is to use them in progression: paint, then start with the coasest grit appropriate (on smooth paint thats gonna be pretty fine) and sand the whole piece. then take the next finest grit and do it again, and then again with the next until youre at the finest you have. the purpose of each of these was to take out the scratches left from the previous grits, down to a more or less microscopic level, or at least fine enough that your next coat of paint will fill them. the purpose, then, of the FIRST sanding was to smooth the raw paint (or primer) you just shot and remove any runs (hopefully not) or dust specks or other problem areas like orange peel (a rough surface of the paint caused by one of many reasons) and then following sandings are essentially to remove the scratches caused by the first sanding and subsequent sandings until they no longer matter.

these two previous paragraphs apply anytime one sees a term like "sand the body" (in other words: easier said than done).

at this point you have a fully primed body to begin painting on. personally i would then give it a light but complete final sanding with fine grit sandpaper, wet as above. try not to break through on the high spots especially if youre going to be finishing with a light color or "glamour" finish, like pearl or deep clear or candy, etc...because in those cases this stage is critical...any variation in the base will probably be visible in the final product.

so now you can lay on some color. there are lots of postings and will be lots of posting on this subject because its the heart of the matter, but basically you want to lay down some color, let it dry, then either build up some more color or lightly sand the color finish ("color sand"), again with pretty fine grit, being very careful not to break through to the primer or worse yet the plastic color. repeat as necessary to achieveat some point you want to shoot a final coat ("flow coat" is what its sometimes called) of paint that will "flow" out and smooth itself. note that during this step you may have gone through more than one iteration of paint-sand-paint-sand etc before the flow coat was put on.

at this point you let the whole mess (hopefully not) dry.

let me explain "dry". if youre using for instance model master enamel paint...and you live somewhere like oklahoma where if i recall correctly you have damp and stormy conditions even during the summer, that little word "dry" is gonna make a big difference. because especially if you spray thick coats (and you will have a hard time avoiding that if you are using spray cans) its gonna take a LONG time to dry. like on the order of a couple weeks minimum. if you have a food dehydrator, you can speed that time up considerably. but if you get impatient and start trying to sand on paint whose skin is hard but is gooey underneath, youve just ruined your paint job. so drying time is a must. most use this time to either build other parts of the model or work on other projects (or lose interest completely!) and note you have to let it dry after EVERY coat of color that you intend to sand.

primer dries pretty quickly though even in damp climates

laquer ditto, like tamiya spray paint, highly recommended, dries very quickly.

i dont know about hardware store brands like krylon, seems to me they usually dont take too long either but im in california where its hot and dry so sometimes the air itself is like a dehydrator!

anyhow if youve followed along this far, it gets easier from here, sort of.

so now youve got this dry, painted body, but you may look at it and think, yeah it looks painted but it doesnt really look "real".

and thats where you start to figure out why they call them "finishes" on real life cars. you gotta "finish" them.

before you can do that though, most people spray clear over the final color coat, and that can involve a senario much like described above, with spraying, sanding, and spraying again until the clear is just the depth and consistency you want it. this has the added benefit of when we get to the "finish" stage, there will be something to "finish" instead of the raw color flow coat that will be underneath the clear...this is good because it will give you some leeway before you sand just a little too much on that highlight and the color of the primer starts showing through! the dreaded cut through at the last stage!!! woohoo its happened to all of us and it aint pretty!

so, im about out of breath now, but if you followed so far i will let someone else forward on with the hard part, or really if youve done the color and clear well up to now you will actually have a very presentable "finish" just from that.

oh couple of clarifications: in my explanation ive been shooting paint like it was holy water. theres a problem with that, a few actually:

1. paint is thick, a lot of paint is really thick. unless youre building a flat sided lead sled, its gonna hide a lot of detail if you put it on too thick. thin is good but very difficult to achieve with a spray can without a lot of practice.

2. thick paint takes a long time to dry, mentioned above

3. paint is also expensive...if its tamiya its very expensive.

4. to keep thick coats of paint relatively thin, you need to sand each coat. this becomes very difficult in tight or detailed areas. you might want to shoot one coat on those areas then mask them off until the final coats so they dont get too much buildup by the time youre all the way through the cycles.

anyway dont let this scare you, in fact in your situation you wont have nearly the long chain of events described here but do remember: black is the #1 worst color for hiding bodywork or waves or imperfections in the body of a car. on the other hand its pretty easy to make look decent to very good esp if the body panels are straight.

anyway im sure many more will add to this and even if not believe me ive neither scratched the surface (npi) nor am i even an expert, ive just had a few years experience and painting has always been the most frustrating thing until i finally kind of got the hang of it and by "it" i mean spraycans. i think "real" painters use airbrushes but ive not gotten that far yet. do some outside reading too, like i said theres a million articles covering this subject in depth...as deep as the finishes!

ps: a couple more things:

1. primer is thin and dries quick and is easy to sand. thats why you use primer to check

your body work initially instead of using "real" paint...especially the part about it drying quickly and sanding easily

2. tamiya paint is worth every cent you pay for it: it sprays thin (otherwise pretty much impossible for a spray can paint), it dries fast, it sands well, and it looks absolutely killer. the downside as mentioned above is cost: its pretty expensive but like a lot of things in life, you get what you pay for. the only issue ive had with it is the clear: it sprays so thin its hard to build up a decent coat for final polishing (not really gone into in my explanation above but thats what gives paint a "finish" that looks real).

3. do NOT spray tamiya paint over just about anything except maybe primer made by another manufacturer, or if you do, test on a scrap piece of plastic first. tamiya is rather "hot" paint and has a rep for ruining underlying paint from different manufacturers. its not a good idea to spray other manufacturers paint over tamiya either but ive not had problems with that at least as far as shooting model master clear over tamiya color...again test if you care about your paint job!

4. model master makes a laquer line as well as their typical enamel. its far better as far as thinness and drying time goes...almost approaches tamiya in that regard but i dont think it gives as smooth a finish as tamiya. youre likely to find what ive found: if its tamiya its usually the highest quality around.

hope all this helps!

Edited September 6, 2007 by jbwelda

[jbwelda]

so no one else has any tips to offer this beginner and newcomer?

what are you all holding out for that book youre planning on writing and making a million on?

thats kinda weak if you ask me.

i thought the idea was to share knowledge not hoard it so you win some obscure contest with all your "secrets".

or maybe i just did such a grand job? somehow i doubt that...

[ismaelg]

Somehow I missed this thread yesterday.

I haven't read Bill's response so this may be repeated.

This topic can be very extensive. But I'll try to be short.

First of all, the 150, 280 and 320 grits are too coarse for modeling use. I suggest to use 400 and up.

You mention you stripped the paint. I assume there is no damage to the plastic. Try to remove as much as possible of the paint without causing any damage to the body. If you sand it too much you will eventually take away details and distort the surface. Once all or most of the paint is off, wash it and make sure it is clean and dry before proceeding. You don't mention what primer you have. Make sure it is compatible with plastic AND compatible with the paint you'll use. Lay down a light coat of primer and let it dry. Wet-sand it with 400 or 600. This means use plenty of water, but work slowly. Make sure the surface is smooth and then apply more primer. Once dry, lightly sand it with 600 or 1000 grit paper to smooth it out. Then you are ready for color paint in a similar way.

I know this is very generic, but the most important advice I can give you is: Do not go to any further step until the current step you are in is absolutely the best it can be.

The biggest mistake you can make is doing a lousy job on a particular step hoping for the next one to compensate and cover it.

Regardless of what you use: rattle cans, airbrush, enamel, laquers or unobtanium, the key to a good paint job is NOT to move forward until the current step is as good as it can be, and making the next step virtually not needed.

What I mean is that no step can cover for a lousy previous step. Primer will not cover mold lines or bad body work. Paint will not cover rough grainy primer, and clear will not fix blotchy paint. On the contrary, problems are usually amplified by next step. It is tempting to shoot clear or color before been ready for it, but at the end you'll end up either with a less than desirable result or doing it all over again.

I hope this helps. Let us know how it goes and feel free to ask if you have any specific question.

Thanks,

[Luis Ayala]

I think William and Ismael covered just about everthing... so I will just go over a few more things...

The first thing I will say is DO NOT get dissapointed if you are having issues with your paint job, cause we all have had them. The most important thing is that you keep practicing untill you feel comfortable with it. Practice is the key for success so the more you practice, the better your skills will be. You don't need a kit to practice, you may use any plastic media you find available, or even on metal.

The key for a nice paint is the prep work so make sure you wash all parts througly before laying any primer or paint over it. Keep in mind that your hands will also need to be clean while handling the kit so wash them once and then while you work on your kits.

You must pick a spot to paint where your work is protected against dust and other airborn particles. A painting booth is a nice thing to have, but those are quite expensive, so a big package box will do for a while.

As for the sanding, I always use 400 grit to get rid of mold lines before primer. You will find many options for primer selection, so since you are doing your first kits I will suggest you look for lacquer base primer in spray can. There are good automotive lacquer primers for about $5.00 and up that won't hurt the plastic.

Painting a model kit is the same as painting a real car, you need to sand, use body filler, primer, sand it again, more body filler, more primer, untill you see a smooth and even surface for the paint to be laid on.

I personally use 1000 and 2000 grit over the finished primer to leave some pores for the paint to adhere.

Take your time, don't rush your paint job, you will find all the information on wich primer to use, wich paint is better, spray can Vs airbrush and tons of things here in this forum, and beleive me you will get all the help you need to get that smooth and glass shiny paint job you are loking for.

Remember, keep it clean, don't rush it and pick a clean spot to work and the most important thing is that if something works fine for me, doesn't mean it will work fine for you...

There are basic things that will lead you the way, but practicing and testing is what will help you choose wich will be the one thing that works best for you...

Keep up the good work, and welcome to the forum!!!!!

Luis

[cruz]

One word, PRACTICE!!!!!!!!!!!!!!!!!! You will come along.........

[m408]

Hey Austin,

Just a comment, and then, a tip or two.

I'm 74 years old and had been out of modeling for over 40 years. Once I got "re-started" I have found these forums to be of great value in catching up. I disagree with the response that some of the "master modelers", and I use that term because I'm constantly awed by their work, would with hold information so as to not divulge their "secrets". I have submitted many, many, questions, and have gotten a bunch of tips and ideas. If you only receive a few answers to your questions it is because others think that the subject has been covered and they don't have much to add.

O.K. now the tips:

1- Go through all of the subjects on the forums which might be of value to your problem, in this instance, painting. You will find many tips on primers, sanding, finishing, paint/primer compatibility etc...

2- Hit your local dollar store and pick up a bunch of plastic spoons. Mine has them at $1.00 for 52 of them. Then experiment. Try different primer/color combinations, sanding grits, and drying times. You can make notes on the spoon handles about the combinations for future use.

Just remember, you can't fix an old problem, only magnify it. Treat each coat or application as if it were the final one. When I was young and building 1:1 street rods my motto was "each part is a hood ornament". Didn't matter if it was a tie rod, steering column, or a primer coat. If you didn't want it seen, don't show it.

Hope this helps.

[Randy Kern]

Austin, the best tip I can give you, is if there is a model car club in your vicinity, join it! I get a lot of good advice and tips from this forum, but nothing beats getting together with your club brothers and trading advice, getting help with problems, finding parts or kits, watching a how-to seminar, or just talking model cars. You will definitely see your builds improve, and have a great time, also.

[bobss396]

I just saw this myself, had a busy weekend. I really don't think that a super long tutorial is the way to go. Just steer him away from the "john wayne wipe" sand papers, get him on track with the right primer and paint combinations.

A good place to get decent sand paper is at auto parts stores. Many of them carry small packs of 3M paper in anything from 150-2000 grit. Stick with 400-2000 grit for model use. Always try to sand with the grain, also wet sand under a trickle of running water or use the dip method.

Get into the habit of using the same brand primers and paint if possible. Experience tells you what else works, but keep it simple to start.