Painting questions

[PhantomLimb]

I'm hoping I can get a little advice about painting.

I've checked out a few tutorials and understand the basics and techniques people use, but have a few questions that weren't really answered in those guides, and hope to get some tips to make things easier. It's my first attempt at something like this and I'm hoping with some time an effort to make it look good instead of half-assed.

What I'm planning to do is to paint an old case I have and a laptop shell. I've done the basic prep getting everything ready, but have a few questions.

With primer does it have to be from the same brand, or can you mix n match if it's gonna be used with the same type of paint?
Anyone have any experience with Rustoleum paints, as in how they go on, and last?
Sanding between coats of paint should be avoided unless it's needed (Peel, bubbles, etc.)?
In laying down multiple coats, will it affect things if I wait say a few hours to a day between coats, or just follow the directions on the can?

Hopefully with the forum stable, this won't go bye bye.

Thanks in advance for your help and advice.

 

[oneil]

ibArcy, I want more info

 

[Jbrow215]

1. it dosent HAVE to be from the same brand, but it is recommended. I'd stay away from low-end generic paints, b/c they dont hold as much quality pigment as the mid-range or expensive brands.

2. I never used rustoleum paint for case painting. It depends on what kind of finish you want.
If you want a matte finish, then use Rustoleum (are you planning on allowing your case to be exposed to weather? )

if your looking for a mirror finish, I highly suggest paints you can find @ autoparts stores. They have touchup cans and give very solid finishes.

3. sanding between coats is a must in my book: A. you open up pores so that more paint can adhere to each coat. 2. if done correctly, you'll have a very professional and smooth look/feel to your finish.

4. I'd wait at least 24hrs. between each coat. You want each coat to cure fully. Especially since you'll be sanding it after, you want the coat to be fairly strong and dry.

hope it helped, and good luck.

 

[Arcygenical]

The quick and (hopefully not so) dirty guide to painting your STEEL or ALUMINUM computer case.

Alright, so you want to paint your case. Awesome, Lot's of us have been there, many of us have tried, and few of us have succeeded. Over my many trials (and even more numerous, errors) I think I've discovered the way to get a good semi-glossy paintjob that doesn't require the better part of a month to get done perfect. Month? Yes... that's right, I said it. Month. Most of the high-gloss perfect show finishes can take upwards of 2-3 weeks to get perfect. If you're looking for that type of a finish, go elsewhere. MNPCtech has a great guide for a perfect show-car (or piano lacqueur, your choice) finish. But for now, we're going for a nice, rugged colour that can withstand the abuse that almost any modder, or gamer, can dish out.

The materials

Preperation is the most important part of any paint job. Thusly, you need some great materials to get a good finish. What you'll need...

1. Sandpaper: 220g, 400g, 1000g and possibly 2000g should do it. 3 large 8x11 sheets of each is a good starting point.
2. Primer. Self etching primer is best... but it can be hard to find. Any primer that's close to the colour you're going to be painting is good if you can find it... if not, gray/white is good for lighter colours, black/red for darker colours. Good metal primer is key. Get it from the AUTO section of a multi-hardware store. You'll want 2-3 cans to do the EXTERIOR of a case. 4 cans for interior + exterior. For aluminum cases, get aluminum adhesion promoter... It's a different sort of primer alltogether!
3. Colour paint, the colour of your choice. Any metal paint will do. Rustoleum, duplicolor, any appliance epoxy, tremclad and krylon fusion (for plastic parts) all get my recommendation. Using car paints is often a good idea too, but they're very expensive for a half-size can. Inside paint should NEVER be glossy IMO, so a rust paint (tremclad) get's my recommendation.
4. Clear coat. Matte or glossy depending on what you want. This should also be from the autoparts section. 1-2 cans, rattle ball clear coat cans should be avoided IMO.
5. A tarp
6. Some dish-soap for sanding, and water.
7. An oven you can borrow for the afternoon. This oven should, preferrably be one used ONLY for paint-curing (more on this later, the secret to my guide...) but if you're only painting once or twice, you can use your kitchen oven. I'll describe how to clean it up afterwards, so don't worry.

Preperation [H] (haha)

Take the case apart. If you're only painting the EXTERIOR of the case, remove the panels and the top. You might need to drill some rivets out to remove the top... You'll need to re-fasten the case with screws or more rivets if drilling is required. Don't paint the case as a whole! If your case does not dissasemble as easily, like some aluminum lian-li or silverstone cases, make do with what you have... mask off any areas you don't want painted, and follow along as best you can. This guide is not meant for those types of cases.

If you're painting the inside of the case as well, remove any drive cages (if at all possible) and other pieces so you're left with a shell. Inside case painting will be covered in it's own section, so leave all this stuff aside for now. All you need is the 2 side panels, the top panel, possibly the front panel (some metallic front cases)

Alright, the hard part... If your case is already painted (either by yourself or by the factory), and scratch free, you're good to go! Sand it down with 220-320g sandpaper to remove the top layer of dirt and oil. You don't want to see any metal.

If your case IS scratched up (deep scratches especially) you'll need to sand ALL the paint off. With your 220g sandpaper sheet, go get some water and a tiny bit of dish-soap. Outside, or in the bathtub (acrylic plastic tubs can scratch easily, so be careful!) spray the surface of the piece you're sanding with water, and with a finger coated in dish soap, lather up the surface a little bit. You don't want bubbles, but you want a nicely lubricated surface (this prolongs your sand-paper's lifespan). An orbital sander works nicely too, but I've never had great luck with it. Hand sanding has always been the best for me.

Start sanding in a circular pattern to get down to bare metal. Remove all the paint on each of the pieces and get down to bare metal. After metal is reached, start sanding in ONLY the same direction! Right to left, left to right (or up to down, down to up) don't turn the piece at all. All the sanding grains should be in the same orientation now. Repeat this on all pieces and let them dry completely. A rub down with rubbing alcohol or a hard spray with soapy water is good to remove any oils on your hand.

Steel and aluminum cases will oxidize very quickly in open air! Get ready to start painting ASAP. Don't leave these out for very long, oxidization you can't even see can hinder paint adherance.

Priming the exterior panels

Almost ready to start painting

Lean your workpiece up against something (you can hang it too) with the tarp behind it. You never want to paint a piece that's lying flat!

The key to good painting is to start spraying before the piece, pass the spray-focus point over the piece, pass the piece and stop spraying... for example spraying left to right:

START SPRAYING ........... | WORK PIECE | .......... STOP SPRAYING

You start spraying on the tarp BESIDE the piece, sweep over the piece, and stop spraying AFTER the piece. This way you don't get any paint buildup at the start and stop points (as soon as you stop moving the can, you get a glossy buildup that detracts from the final piece).

Using many thin coats is the key to painting... One big thick coat is a death sentence! Primer is more forgiving, but the colour coat should take about 20-30 passes with the can before it's even remotely completed... You want to cover about 2-3% of the piece every time you spray, let it dry (2-3 minutes) then contine. MNPCtech has a great video segment on this method, they've said it better than I can.

After you get a complete coat of primer wait about 45 minutes and sand it lightly with a high-grit sandpaper... 800-1000 is perfect for this. You do NOT want to re-expose metal!

Clean the piece after the light sanding, and spray again. A thicker coat this time should be ok.

Sand it again after a full hour drying time, and let it oven cure for an hour.

Oven Curing?

Yep, the secret to a GOOD paint job is oven curing. Memorize these steps as I'll be referring you back to them many times.

Preheat your oven to it's lowest possible temperature... Anywhere from 130-150f is perfect for this.

After the paint (either primer or colour) has sat on your piece for at least ONE HOUR (it should be tacky or dry to the touch) you may place it in the oven for 1-2 hours. Place the piece in the center rack of the oven, close it and wait ten minutes.

After ten minutes has passed, open the oven to release the fumes from the paint, close the oven and turn it off.

Come back in 2 hours and remove your piece. It should be cool-warm to the touch.

It can then be sanded down (800g for primer or 1000g for primer) cleaned off (paper towel) and re-sprayed with the next step. If this is the first time you're reading this section, it's time to start spraying with the colour coat.

Only bake 1 piece at a time. Baking more pieces at a time can cause a buildup of harmful gasses in the oven which are toxic to most life on earth.

Keep the kitchen range-hood fan on during this step

Colour Coat

Ok... So... The big deal . You've got 1-2 full coats of primer on the case, let it oven cure, and lightly sanded and removed any dust/grime/overspray from the surface.

Using the same sweeping technique as described in the primer section, start coating the piece in colour coat. Once again, very light layers (almost like using the spraypaint tool in MS Paint... notice how it only covers about 20% of the area it's capable of covering? That's what you're doing, but you want even less coverage than the spraypaint tool can put out... roughly 10% of that)

After you have a full coat of paint, let it dry and cure it in the oven. Sand it with 2000g sandpaper.

Apply a second coat in the same manner the first one was applied. Dry, Cure, Sand.

Apply a third coat if you wish. The more the better. Just make sure each coat is PERFECTLY dried (3hrs total, 1 outside and 2 inside the oven, or some combination of that) before applying a new layer. Rushing the coats risks removing the old layer of paint and creating a bubbly surface.

If you're spraying upright or directly at the piece, you shouldn't get any runs or drips in the paint surface. Light coats prevents the entire coat from sagging towards the bottom of the piece. If you DO get a run, let it dry completely (4-5 hrs in the oven) and sand it down with 400g sandpaper... Sand the entire surface with 1000g sandpaper and apply that coat again.

Do that for each of the 3 main exterior pieces.

After your satisfied with the coverage, let each piece sit for 4-5 hours. They should then be oven cured (you can do them all together now, since they've sat for 1/4 of a day) in the oven for anywhere between 3-6 hours. You can leave the heat on for the first HALF of this curing, and remove it for the 2nd half.

Curing really is the KEY to a good coating. If done properly with good paint, you could scratch the case with a penny (after the final curing of course) and only get a hairline of discolouration. I've dropped hammers on my side-panels after removing them from their final 24 hour cure (I've got a paint curing oven that operates at 100f) without damaging the paint in any way!




I'll continue this later. I'm going out to lunch with my girlfriend

 

[HardTech]

4. I'd wait at least 24hrs. between each coat. You want each coat to cure fully.

Hardest rule to follow

I’m getting my setup done with car paint. The spray stuff doesn’t work for me long term.

Its hard to say, but it never sets. Leave something on your case for weeks with the room temp being 85 and watch what happens :/

I have a perfect CD impression in my case.

Yes the case was done right primer, wait, paint, wait, clear, bake, wait.
The issues happened after the winter months, it had been 90+ days since it was painted, so it was as cured as one would have gotten.

Just be careful afterwards. You can make it look good, but the paint can not withstand abuse like car paint would. It chips, scratches, and forms into objects. But if you treat it right, you will have a nice case. Good luck.

 

[Arcygenical]

Hardest rule to follow

I’m getting my setup done with car paint. The spray stuff doesn’t work for me long term.

Its hard to say, but it never sets. Leave something on your case for weeks with the room temp being 85 and watch what happens :/

I have a perfect CD impression in my case.

Yes the case was done right primer, wait, paint, wait, clear, bake, wait.
The issues happened after the winter months, it had been 90+ days since it was painted, so it was as cured as one would have gotten.

Just be careful afterwards. You can make it look good, but the paint can not withstand abuse like car paint would. It chips, scratches, and forms into objects. But if you treat it right, you will have a nice case. Good luck.

I'll bet this is due to the clearcoating... Either the clearcoat has re-saturated the colour coat with the accelerant solvant (the stuff that pressurizes the can and evaporates as the paint dries) or the clearcoat its self has managed to melt... If you were to buff the clear coat out with some nice micro-bead polish, I bet the impression would go away.

The waiting time before the clear coat on any case I use is anywhere from 10-30 days AFTER a 48 hour low-heat cure time.

The clear coated case is then put aside for a month to degass in a room heated to around 27c.

 

[HardTech]

Auto paint with hardeners is the best way for me. (I guess im abusive)

Nice guide and I will remember it.

 

[PhantomLimb]

Arcygenical: That's a great guide, I will keep this for future use.

One question: Will it matter if I don't do the heat curing, and just let it do it's thing at room temperature? If I use the oven for curing, my better half will void my warranty

Thanks again to all for any tips or suggestions.

 

[Arcygenical]

Arcygenical: That's a great guide, I will keep this for future use.

One question: Will it matter if I don't do the heat curing, and just let it do it's thing at room temperature? If I use the oven for curing, my better half will void my warranty

Thanks again to all for any tips or suggestions.

Heat curing is not necessary, but you'll need to wait at LEAST 2 days between each coat of paint... That makes a simple paint job take upwards of 8-10 days...

If you don't wait, you won't get good adhesion, and it will chip off much easier.

Leaving it in the sun after it's dry to the touch for an afternoon should do it too, cutting the dry time well in half. I'm doing that right now for an outdoor ornament... If you need any clarification I might be able to take a video or 2.