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#1 Com_VC

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Posted 10 March 2008 - 02:12 PM

Hi,

Just wondering if there are any diy guides/forums on painting around, I used to have a few links but lost them due to computer failure.

I'm going to start my first respray in acrylic shortly and I want to read up on as much info as I can.

Maybe this could be made a sticky.

Heres one I found on oldholden.

http://holdenpaedia..../Spray_Painting

Thanks in advance

#2 _Yella SLuR_

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Posted 10 March 2008 - 03:34 PM

God, where do you start?

I think painting a whole car is the way to learn. You are painting long enough to try things out with the gun/paint on the primer coat rather than from just doing odd bits and pieces.

Thinners are your friend, 1 part paint to 1.5 parts up to 2 or more parts thinners, particularly top coats. Just discovered the magic of retarder thinners, but get your technique right first before you start using these or you'll end up with runs left right and centre. Use good quality thinners and paint.

The biggest thing is it is all in the preparation, the painting is the easy part. Be particularly mindful of deep scratches, the acrylic will sink back into them as it dries.

Invest in tack rags.

Avoid the old wives tales: wetting down the concrete, leaving it for a month to compound, etc. just be sensible and take reasonable precautions.

Make sure your surfaces are clean.

Try paint with maximum paint (on the job, not in the air) and minimum air pressure (about 40 psi).

Make sure you have a water trap, and that the main part of the air line 8-10m, runs downhill toward the compressor. Don't mount your water trap on the compressor (see that so often).

No matter what, never go over the same bit twice. You'll be doing plenty of coats, so plenty of time to get it next and successive coats.

Since you are learning, be prepared to sand it all off and start again if required. It's quicker the second time round anyways.

Mmm, that's the sort of things I do. Have a look at paint compounding for finishing the paint off. Nearly as full on as preparing, but not quite.

Edited by Yella SLuR, 10 March 2008 - 03:35 PM.


#3 _Yella SLuR_

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Posted 10 March 2008 - 03:43 PM

Just ask questions as you go and we'll capture it.

It's a weird sort of art, you always can see what you could of done to make it better once you've finished.

Pete's done some great articles on prepping your work. They are stickies already.

One thing for sure, you never stop learning with painting.

Edited by Yella SLuR, 10 March 2008 - 03:45 PM.


#4 Com_VC

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Posted 10 March 2008 - 05:44 PM

Thanks for that.. Ok the questions start.

Engine bay is in bare metal, so are the front pillars and around the front and rear screens, has been so for about 3 months now, can�t really see any rust showing. I bought some septone rust converter awhile back to use on it but am a little unsure if I should or not as I�ve never used it before. I read the label and it says do not apply to painted surfaces as loss of paint adhesion could apply. Just worried if I accidentally brush a bit on the paint somewhere.

Now sanding, not really looking forward to it. But the local paint shop told me to go for 180 grit to begin with and then step up to 500 grit to finish it off. These will be used on a 150mm D/A sander. Does this sound about right? I am going to do this on the primed bare metal areas and the rest of the car.

Also on the paint tin is says 60% thinners/40% paint. Should I stick with this ratio? I bought a 20L drum of acrylic thinners, so should have plenty there to clean the guns etc.

I�ve got a water trap and adjustable reg on the gun ready to go. The hose is about 15 metres long, compressor is 16cfm with a 50L tank.

How many coats of primer should be applied over the bare metal areas? From what I�ve heard I wont need to apply it over the existing paint.

How many colour coats? Will the final coat need sanding?

How many clear coats?

Regarding compounding, I�ve been told wait at least a week for that?

Also the paint I am doing is a metallic so it�s probably going to be a little more difficult.

Also the tip on my gravity feed spray gun is 1.4, will this be ok?

Sorry for all the questions..

#5 REDA9X

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Posted 10 March 2008 - 09:12 PM

My tips would be this
Do not skimp on tapes, buy a decent tape like 3M, it will cost more but it lasts alot better and it usually has more tape on a roll than the cheaper stuff.
Preperation is everything, make sure you have a good surface. Don't be afraid to put on plenty of coats of primer, you are going to be sanding it back smooth anyway, you don't want to go back to the metal. Put it over the existing paint if you are going to be sanding back the existing paint at all. Ratios can vary according to your paint, you can go a little thinner, but never thicker, your paint will splatter out and become dry if it's mixed too thick. Do a little practice run with your settings.
A 2.0ml tip is better for acrylic and is good for your filler primers too.
What yella is said is right, do more coats, don't try and get all your paint on in one hit. Colour coats, well, that depends on how thick you spray it on, make sure you put more coats on areas that may buff through like edges. Paint them first then the panel and go back over the edges again.
As for sanding back, yes what they told you is about right.

#6 _Yella SLuR_

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Posted 10 March 2008 - 09:43 PM

Mmmm, not much to add.

Yup, you need 2.0mm for acrylic, not sure if that changes for metallic. I'd double check at the auto paint shop on that one, but I think you'll find it is still 2.0mm. A 1.4mm tip is for 2 pack.

Red, are you talking the 3m fine liner tape, or all tapes? If you are masking lines for blackouts etc, 3m fine liner is definitely the go. Very nice to use.

Yeah, rust converter is good. Don't worry too much about the comment about avoiding paint surfaces. It discolours the paint if you get it on the paint, that's about it. I think it is an ass covering statement by the manufacturer. Its turned the white paint on the race wreck purple!!! You'll clean it off with your sanding at any rate (apply prior to sanding).

Sanding, yup, that's all correct. You can use dry papers for the prep work, only need to move to wet and dry when you are trying to get your final surface, starting with 1500 grit. Watch your edges, ridges, etc. sandpaper loves these. Dunno what a D/A sander is, but if that's what your comfortable with, go for it. I use disks (need right technique) to take of top paint, and soft sanding pad or rubber block for detailed areas.

Personally, I do one primer coat, sand it smooth, then do another. The second one doesn't get sanded, it receives the top coats direct. I resand every four to five colour coats. Sanding after the first four will give you a feel for how thick your paint is. If your going through, you may have to do six coats to match your painting style, etc. if you get the drift. It serves as a really good dress rehersal for the final compound/buff.

Now on solid colours we mix 50% paint to clear coat to avoid getting shadowing. I'm not sure with metallic, as I've never used metallic. I think your action has to be alot more even and consistent with metallic as well to get consistent pattern of the flakes, but again, I've yet to play with metallics as yet. My first car turned me off metallics, as you could see where different painters had fixed up panels!! Different light off em from the metal flake, but I digress. Clear is great, like putting an extra five or six coats on, adds such depth.

Don't put more paint on your edges. You'll get a feeling on how precious your edges and ridges are when you get the first four coats flat, even the primer. If you are scared of buffing through, put masking tape on your edges to protect them. If your tape comes off when buffing, stop the buffer quickly. I bought one of those Mother's Palm Polisher's from Supercheap. Seam to be the go. The "won't burn the paint" got me. Seems OK, and will take industry standard foam pads with a tiny bit of modification to the pads. Buffers go alot slower than angle grinders, so don't be tempted just to throw buffing pads on your standard angle grinder.

Edited by Yella SLuR, 10 March 2008 - 09:46 PM.


#7 _Yella SLuR_

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Posted 10 March 2008 - 09:52 PM

Oh, 40 paint 60 thinners is the same as 1.5 thinners to paint. That is the least you can thin your paint (the starting point). Don't know how much it holds true, but I've been told the more thinners, the higher the gloss. Don't know if that is the case, but the more thinners certainly makes the paint sit flatter (read less sanding) If the paint beads off a mixing stick when you lift it out of the paint, that's too thin, it should be on the edge of streaming off, and beading (general rule of thumb). Consistency will also change with temperature and humidity both when mixing and painting with the gun (constantly adjust the gun to try find the best setting at all times, only needs small changes). In the early days, I used to even finish off with 100% thinners (turn down volume control) to make the paint sit flatter.

Oh, grap a crap door off a random car to practice your buffing before you attack your paint. Again, it will give you a feel for how precious your edges and ripples are.

#8 _CHOPPER_

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Posted 10 March 2008 - 11:04 PM

Yes, practice on some scrap ( any locol Ford should do ) and keep practicing.

#9 Com_VC

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Posted 11 March 2008 - 08:41 PM

Thanks for the advice so far :)

mixing 50% paint with 50% clear, never heard of that. Is that one of those tricks of the trade sorta things. I always thought you just mixed the clear with thinners and away you go.

Also filler, the other day I got told it was ok to use lightweight body filler over existing paint if you primed the filler afterwards? From what I read on the body filler tin it said it had to be taken back to bare metal first.

I read somewhere that i'd have to use fine filler to go over existing paint?

#10 _HDTXU1_

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Posted 11 March 2008 - 09:07 PM

In regards to mixing color and clear together not a good idea if it is a solid color it will go milky in time as the clear will fade at a different rate in a metallic you are also asking for trouble. Clear coat is just that. When you are painting a metallic your main concern is to get coverage so even coats are the go the clear coat is what gives the basecoat its shine. Also when putting on your basecoat if you get any bits of dirt or hair or muck in it you can wait until it (flashes off) or almost drys then gently rub them out with 800 or finer paper then basecoat over again.
This is a good idea because you wont be able to buff out dirt or muck out of the base only out of the clear coat. As for the filler that can go over paint it is refered to as 2pac or fine filler it can be used for small repairs or pin holes in normal filler repairs. It is great stuff but you must finish it of in fine paper ie 240 or even 320 for a great result. Take your time and practice a bit on a ford.

#11 Com_VC

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Posted 15 March 2008 - 03:11 PM

When doing door jambs, inside boot area etc is it necessary to clear coat if doing a metallic colour?

#12 _Yella SLuR_

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Posted 15 March 2008 - 03:37 PM

Mate, have a go with with your clear coat, certainly if doing metallic, I'd do 100% clear, no colour mixed in. I don't necessarily agree with the above comments. Even with 50/50 for solid colours you still get the depth and shine, in fact with no clear coat you get the shine with solid colours. Yella has no clear coat.

Acrylic doesn't flash off, that refers to the chemical reaction with two pack.

Yup do the door reveals with your clear coat as well, you want the same depth in all your paint.

I was surprised when the paint shop advised 50/50 clear and colour as well, but I think the results speak for themself. With solid colours we were advised that their is an issue with the clear creating shadows if using 100% clear. As metalic has a texture from the metal flake, I dare say it isn't an issue.

Posted Image

Feel free to post pics of your paint jobs.

Edited by Yella SLuR, 15 March 2008 - 03:44 PM.


#13 Com_VC

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Posted 15 March 2008 - 04:52 PM

Will try and get some pics next week, hopefully some of it will be done then. I'm a bit nervous lol, never done a car before but have painted quite a few various items using a spray gun before with fairly good results.

#14 Com_VC

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Posted 16 March 2008 - 07:49 PM

Regarding paint pressures, you mentioned 40psi. Is that for a suction feed gun or gravity HVLP?

I've got both, the suction feed has a 2mm tip in it and the gravity has a 1.4 which I will need to change.

Would a gravity feed gun be easier to use? I've only ever used suction feed before and I found paint coming out the hole in the top of the pot annoying.

#15 Com_VC

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Posted 23 March 2008 - 01:50 PM

Quick question..

How long should I be waiting between each colour coat? Is 2-3 minutes acceptable?

Also how long should I wait till I put the clear on after i've finished with the colour coats?

#16 Heath

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Posted 23 March 2008 - 03:38 PM

40-45psi for gravity works wonders for me.

2-3 minutes is fine but you don't have to rush it that much.

#17 _Bomber Watson_

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Posted 23 March 2008 - 06:01 PM

If you have a HVLP gun then you will need a special compressor that puts out about 30cfm at around 15psi. Your average home compressor wont come close to this. I think you probably have just a normal grav feed gun.

Im not going to comment to much on processes because i disagree a lot with some other posts here. Mind you i also agree with some other posts. Will probably cause a shit fight none the less. If you want my opinions PM me.

Cheers.

#18 Com_VC

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Posted 23 March 2008 - 07:12 PM

It says HVLP on the gun itself but it's an ebay china gun so yeah not sure what to believe.

#19 _Bomber Watson_

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Posted 23 March 2008 - 07:27 PM

Yeah lots of people look at a grav feed gun and think there all HVLP, not so.

Hell, Star even markets guns as HVLP when there not really HVLP guns. Thats one of the reasons i dislike Star spray guns.

Cheers.

Edited by Bomber Watson, 23 March 2008 - 07:28 PM.


#20 REDA9X

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Posted 23 March 2008 - 08:45 PM

Bomber, I don't agree with some things said here myself, I guess some people have a different way. Being in the middle of painting a car right now i can certainly see the pitfalls.

#21 _Bomber Watson_

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Posted 23 March 2008 - 11:33 PM

I guess some people have a different way.

Very good way of putting it.

Basically when it comes to getting a good finish with acrylic there isnt that much of a right and wrong way. You could brush it on and cut and buff it back to a good finish. I just wonder how some things will look three or four years down the track.

Cheers.

#22 TerrA LX

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Posted 24 March 2008 - 01:31 AM

^^ do you type left or right handed whilst spraying?

#23 _Yella SLuR_

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Posted 24 March 2008 - 09:14 AM

Why don't you guys add to the discussion, rather than dissing it? With those other methods of communication, nobody benefits. I'm sure most don't have a problem with alternative methods and techniques to try. Grow up and speak up.

#24 Com_VC

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Posted 24 March 2008 - 12:35 PM

yep I wont mind :) post away

If i'm getting a peely finish should I add more thinners?

#25 _Yella SLuR_

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Posted 24 March 2008 - 12:50 PM

Add more thinners. How much overspray are you getting? If alot, turn down the air a bit. Unfortunately, orange peel is a fact of life with acrylic, although you can reduce it with more thinners. Only thing I've seen to avoid it is retarding thinners.




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