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#26 REDA9X

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Posted 24 March 2008 - 12:53 PM

Yella, I believe I did add to the discussion a page back, I gave my experiences but apparently they were wrong.

#27 _Yella SLuR_

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Posted 24 March 2008 - 01:21 PM

???? who said they were wrong?

#28 _Bomber Watson_

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Posted 24 March 2008 - 02:29 PM

Ok, from my own limited experience using acrylic.

I'll start with the start, bog work. Because bog is a 2k system, you dont have to worry about shrinkage after it has dried. That said you must wait till it has completely dried before sanding it. Usually 2 hours will suffice. My method is to start at a common point, say the right front guard, put bog into that, then work my way around the car in a clockwise fashion, filling everything. Then i go away for an hour or so, come back and start sanding where i begun. Sand up the guard i started on, refill where it needs it, and keep moving around, sanding one panel at a time then refilling it as i go, then when i get back to the start the first panel is dry enough to sand again, and the process repeats until everything is strait.

Now, when your putting more bog in to fill a slight concave in the middle of previous bog work, dont just slap a tiny little bit into a small dip in the middle. This makes it very hard to sand out. Re cover the entire filled area, going over by about 5cm each time you add more. This wastes a lot of bog, but it definitely helps get it flatter and makes it a lot easyer to sand out. Otherwise you end up with low spots and high spots everywhere, because the metal is very hard, and the bog from last time is slightly harder than the fresher stuff, so you end up with dips everywhere. Just recover the entire area. A lot of people are scared to put heaps of bog on, but basically you sand 90% of it off, and i would prefer to have a bit more filler than to have a wobbly paint job. Once its painted you cant see whats underneath.

You made mention to putting bog over pre painted surfaces. This can be done, but it is better to sand the area back to bare metal. If you must put it over paint, sand the paint with 24g freecut first to get some nice big ridges in it. But honestly you would be way better off hitting the whole area with 36g on either a 5 or 7" sander. When you sand areas back for bog, dont just finish the edge of paint willy nilly. Where possible take it back to bare metal right to the edge of a panel, or a mould line, or atleast finish it in a strait line. Again this will make it easier to feather out. Use a 6" random with 80g next to feather the edge. Also sand any bare metal bits you have that you wont want to bog with 80 for now, to smooth them out a bit, then go over the whole car with 180, then bog away.

Use a 12" speed file to sand back the bog where you can, and use a rubbing block for the rest. If your a bit sloppy, you can smack it back with 80 on the 6" random, just dont go to far. Use 80 on the speed file to get it flat, then when your happy with everything go over it with 180 then the whole car with 240 on a rubbing block. All dry for now. Be careful when sanding the bulk back with a speed file. If you heat it up to much the metal expands, usually comes out a bit, then when you sand it flat and let it cool, the metal shrinks again, pulls in, and your left with a dip. Something else to consider.

Do not get the bog wet. It is basically talcum powder and araldite mixed together. Absorbs water like nothing else, and will fall out later if it gets wet.

Now, after you have all the bog finished and every edge finished with 240 grit dry, its time to undercoat!!!

At this stage i would definitely not recommend you use wax and grease remover (prepsol). Use GP thinners. Why? because wax and grease remover is actually an oil, and it will get soaked into the bog and cause you huge dramas. Thinners simply evaporates out. If the car is currently painted in acrylic you will not be able to do this, because the thinners will munch up the paint. So hit any bogged bits with thinners then do the rest with prepsol.

Acrylic primer filler is beautiful stuff to use, i love it. Definitely start it with at least 120% thinners, and only use that mixture if you have a few ripples still. Use 150% if you have it all fairly good. Whatever you do, dont put on thick coats. Just dust it on, around and around and around, not so dry that it goes all rough, but not to wet either. Remember this is acrylic, and the solvents have to evaporate for it to dry. The thicker you put it on, the longer it will take to dry. Put on at least four coats for now, six will probably be better, and make sure you leave about half an hour drying time for the solvents to evaporate between coats.

Another thing to think about when spraying is solvent boil, this is where you put it on way to thick, and the solvents from the bottom of the paint try to evaporate, and leave tiny pin holes. This is horrible at a finish stage level, but down right devastating in the undercoat stages. Same as you CAN NOT get runs. If you get a run then you have to sand the undercoat back to bare metal in that area, and start again. Otherwise you will always see a slight mark there.

Definetly do not think about sanding anything for at least two days, but longer is always better. After a few hours drying you can go around and put spot putty in any areas needing it though. I recommend Upol Hot Shot, this is a 2 part spot putty kinda like bog, just a lot finer. Excellent stuf and it is hardened by a catalizer so it wont shrink later. BUT if you use this then dont put it in for a couple of days, otherwise the undercoat will shrink under it and cause lots of swearing. If you have single stage acrylic spot putty, feel free to put it in a couple of hours after spraying. Do not sand acrylic spot putties for a few days either, and make sure you only put it in very thin (max of 1mm build), wait an hour or so, then put in another very thin coat, etc etc etc. Because again, this relies on solvents escaping to dry, and if you put it in to thick it will still be shrinking six months later. At some stage, probably when you put in the spot putty, load the gun up with some very very thin (thinned 200%) acrylic black and just dust it over, as a guide coat.

Now its time to sand the undercoat. Not much Really to say here. Start with 240 wet, and just cruise around until most of the guide coat has gone, so you have gotten rid of all your lows and orange peel. If you come across a slight dent, ie a low, do not just stand there and sand around it until its gone. Sand the whole area, coming at least 30cm each way, or to the edge of the panel, in strait across across pattern until its gone. There is a lot of discussion on whether you should sand in a circular motion or in strait lines, honestly i dont think this makes a huge difference, especially at this stage. What does make a huge difference is what you use. Wherever possible, use a block. Where a block isnt practical, use the PALM of your hand. In tiny little bits that even your palm wont fit into, use a finger or two, but because this can cause problems make sure you sand in a circular motion with both the palm and the fingers.

Now that you have finished sanding the undercoat with 240, stand back and have a good look at it. How much metal can you see?? How much bog can you see? If all you can see is little bits of metal around the edges, fantastic. Mix up some more primer at 200% then DUST a tiny bit around the edges you sanded through. Then continue on with other grits.

If you can see a fair bit of metal, and perhaps a few bits where you have sanded back to bog, then you have to re undercoat. This time around you should use prepsol, because thinners will munch up the undercoat. Another four coats should do the trick. Then re guide coat and re rub with 240.

After either of those stages are done, its time for more sanding. But first, re guide coat everything. Then sand with 320 until all the guide coat is gone. If you sand through any edges, or any small bits, get some more undercoat mixed to 200% and DUST it over the offending area. Then re guide coat and sand with 600. This should be fine enough for acrylic. Also, make sure you wash the entire car between grits. Again, if you go through any metal, just dust a bit more very thin undercoat over it. At this stage, you will simply give the areas you re undercoat a quick hit with a white scotch brite pad and its prepped.

Now once all your bare metal has been dusted over and scuffed with white scotch brite, run some prepsol over the car, hit it with a orange tack cloth then its time to spray. This has already been covered fairly well so ill just skirt over the finer points.

Use a grav feed gun with a 1.8mm fluid tip. I usually leave the compressor set at max and adjust the air pressure on the gun to suit my tastes. Get as bigga fan as you can, and you will want a fair bit of fluid flow. To set the air pressure, basically wind the fan control right out and the fluid right out, then start with a high air pressure and adjust the air down until the fan is a nice even long oval. At first (to much air) it will look like a number 8, so keep winding the pressure down untill it looks like a 0.

Probably have the fluid control set at about 2.5 turns out. This varies gun to gun, painter to painter but seems a good place to start. I personally just have it right out all the time and vary how much i pull the trigger and how fast i move the gun, but this takes a lot of practice.

Apply three or four colour coats, mixed at 150% basically until you cannot see any of the undercoat underneath, it looks all even, and the colour is even when viewed from every angel. You dont want to be able to see any spot putty or things like that under your paint. Because your working with metallic and will clear it actual build of the colour is not important, just make sure its covered.

Leave it stealth's 15 minutes between coats to give time for solvents to evaporate. Also, have a good look over each coat while its drying and look for any little bits of shit, if you see any you can wet rub these out with 800 between coats, Leave it to dry for 15 minutes and sand. Then dry, re prepsol the area (with a JUST DAMP rag) and put the next coat over. You can do this on every coat except the last coat of colour, if you try to sand it then you will expose the aluminium fleck and it will look like crap. If you are in a particularly dusty environment then you can hit it between coats with a BLUE tack cloth, just be careful. This can cause lots of problems, especially with silver.

Now for the clear, you can start spraying this around half an hour after finishing the colour, so basically the time it will take to clean the colour out of the gun, put all that away, get the clear out, mix it up, etc, you will be good to go.

Retack the car, using a BLUE tack cloth, then start spraying. Have the paint mixed to about 150% for the first few coats.

Now, unlike the colour, with clear the more the better. You should do at least eight coats of clear, to allow for initial rub back and then future buffing. If you are getting some serious orange peel (which you shouldent), then stop after about four coats, wait a day or two, then lightly rub it back with 800. Also, as with the colour, if you are getting bits of dust then you can lightly wet rub it back between coats. Again, allow around 15 minutes between coats for the solvents to escape.

After the first two or three coats at 150%, thin the paint further to 180%, then apply another three or four coats. Then thin the paint to 200% and apply another two or three coats. This should give you enough paint to cut and buff back later.

Now that thats all done, walk away and leave the car for AT LEAST a week. As with the undercoat, the longer the better.

Rub it back with 1200, 1500, then 2000 to get rid of orange peel and dirt nibs, washing between coats of course, then compound with a very fine cutting compound and a waffle pad on the 7" sander. Use very low rpm and very light pressure. It should come up absolutely beautiful, but if you want you can polish it with a NON SILICONE BASED polish. Meguires markets a few very good ones.

Do not under any circumstances use a silicone based polish or a wax at this stage. Solvents are still escaping from the paint and it will cause massive f*ck ups. Wait at least a month before polishing with a silicone polish or waxing. Honestly, i wouldn't recommend a silicone polish anyway, but wax i definitely recommend. Meguires gold wax is fantastic.

I hope this helps a bit, and hope its not to confusing. Ask if you need anything cleared up. Again, this is not a be all end all of painting guides, just my limited personal knowledge on how to work with acrylic. Personally i prefer 2k paints, but for a beginner acrylic is the go. As i said before you could brush it on and buff it back and get a finish that could win a show if you really wanted.


Cheers.

#29 _Bomber Watson_

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Posted 24 March 2008 - 02:30 PM

f*ck me thats a long post.

Can we prune out the shit and make this a sticky please??? I really dont want to have to type all that again....

Cheers.

#30 _Yella SLuR_

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Posted 24 March 2008 - 04:52 PM

Good stuff.

#31 _Bomber Watson_

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Posted 24 March 2008 - 05:35 PM

Luckily i was bored today, typing that out killed an hour :P.

Cheers.

#32 _nathanrcman_

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Posted 24 March 2008 - 06:34 PM

F**CKING BRILLIANT!

good job! :rockon:

do some of these methods apply to 2k paints too?

#33 _Bomber Watson_

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Posted 24 March 2008 - 06:44 PM

Yeah fair bit, basic differences are to re guide coat and sand the primer with 800 after you have done all the above mentioned stuff, same thing applies with base coat as colour just go until every things covered, and you wont need as much clear. Three to four coats of MS or two to three coats of HS should be fine. Unless your getting a bit of peel in it, then give three coats of clear then sand back with 800 and give another couple.

Also with 2k stuff you dont have to worry about shrinkage, so two days is a good guide line to leave primers and top coats before sanding. With a 2k primer definitely use Hot shot spot putty, dont even think of using acrylic based stuff.

Really, when it comes to spraying 2k clear, when it looks good, walk away from it. When you get to a point that theres no dry spots and a good flat shiny coverage over everything, just pack up and walk away.

Lastly, get the tech data sheets for the stuff your using and mix it EXACTLY as is stated. If it says use 5% reducer, use 5% reducer. Dont mix brands, and use the correct hardeners reducers etc.

I highly recommend Spies Hecker basecoats and clear coats. There HS clear coat is fantastic and you can get an awesome shine with two coats. Very very expensive though.

Cheers.

#34 Com_VC

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Posted 24 March 2008 - 08:14 PM

hmm didn't think you'd have to wait a week before sanding the primer. I don't have a lot of time. I want to have it painted in a few days.

I was thinking more along the lines of spray primer, wait 2 hours, sand, apply colour coats in 5 minute intervals, clear... Obviously a bit more to it than that but that's the sort of time frame i've got lol.

At the moment i've got the bay primed and sanded, i'm going to sand the rest of the car tomorrow and primed and then sanded again. Maybe apply the colour coat towards the end of the day if there is still some time.

#35 TerrA LX

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Posted 24 March 2008 - 08:23 PM

^ Give it a few months and the paint will prolly flake off. Seriously you will prolly get sink back and blemishes.

Edited by ALX76, 24 March 2008 - 08:27 PM.


#36 _Yella SLuR_

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Posted 24 March 2008 - 08:28 PM

I don't think the paint will flake off, but by rushing it you do risk the chance of having to start from scratch. Paint is best not rushed.

#37 Com_VC

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Posted 24 March 2008 - 09:09 PM

What would be the minimum amount of time I could leave the primer before sanding?

#38 _Bomber Watson_

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Posted 24 March 2008 - 09:16 PM

Honestly, a couple of hours, but i would take overnight as an absolute minimum. But you will get shrinkage big time. Will look awesome strait after you have done it, but will look like shit in two-three weeks time.

Depends on what you wanna do mate.

This is really the biggest problem, most people think that its a case of slapping some undercoat on, giving it a scuff, then slapping some paint on and cracking a beer. I have countless people asking me to spray there cars for them on the weekends for a carton, i tell them to get #@$^%& and that its $2000 minimum, at absolute mates rates. When they get all taken aback i tell them to go to a panel shop and see what it will cost.

Cheers.

Edited by Bomber Watson, 24 March 2008 - 09:21 PM.


#39 Com_VC

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Posted 25 March 2008 - 08:18 AM

I guess I could wait a two days before I start sanding if it will gain better results, have a few other things I could do.

So after that it's no more waiting besides the compounding part? I can apply the acrylic top coat + clear in 5 minute intervals or so?

I'll wait a week or two for compounding as there is no real rush for that.

#40 TerrA LX

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Posted 25 March 2008 - 08:56 AM

Sun and wind will be your friend. :spoton:

#41 Com_VC

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Posted 25 March 2008 - 03:09 PM

something else I need to know. When using the 6" air sander it seems to be burning the existing paint up a bit and putting lots of deep scratches in it. Why is it doing this? I'm not putting a lot of pressure on it and using 500 grit.

#42 MRLXSS

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Posted 25 March 2008 - 03:31 PM

Great post earlier DJ! Very informative and will no doubt help many beginners!

#43 _Bomber Watson_

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Posted 25 March 2008 - 06:32 PM

something else I need to know. When using the 6" air sander it seems to be burning the existing paint up a bit and putting lots of deep scratches in it. Why is it doing this? I'm not putting a lot of pressure on it and using 500 grit.

Another problem with acrylic.

As you sand it it melts, forms little balls on the sanding paper then scratches the shit out of everything.

Try moving the sander around more.

Also, 5 minutes between coats would be marginal. longer would be better.

Matty, yeah not bad ey :P. Thought of a few more things i shoulda put in but i cant edit it now so oh well, i must get around to saving it to my computer and then i can tweak it as i think of stuff. Just little things that i have down to pure habit, dont even really think about while im doing them, that beginners might not know.

Cheers.

#44 Com_VC

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Posted 25 March 2008 - 07:29 PM

All primed excect for the bonnet. The paint on the bonnet is perfect, i've got a few small repairs to do on it though. Would it be ok if I sanded the bonnet back with 600 grade to remove the shine, take the areas where I have to do the repairs back to metal, do repairs and then spot prime the areas? Or would I be best off priming the whole bonnet?

I've decided to do the top coat on friday sometime. That way it will give the primer a chance to dry properly or as best as it can in that short amount of time and I can fix up the little scratches etc.

If I had have known about the air sander leaving the scratches etc I would have done it all by hand.

Next time I reckon i'll be using 2 pack.

Thanks for all the advice :)

#45 _Bomber Watson_

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Posted 25 March 2008 - 08:13 PM

Hand sanding has the same problem sadly. And its not just acrylic, all paint systems do it, just acrylic is worst. Well, enamel is the worst, but lets not go there.

Just spot prime the bonnet. But whatever you do DO NOT mask the edges in the middle of a panel. This is impossible to sand out and you will always have a ridge under the paint that is just visible. Just dust the primer around the edge, then when you sand it back you wont even know.

Cheers.

#46 _the gts_

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Posted 25 March 2008 - 09:47 PM

guys what would you do next with a car that is on a rotisary? it has been blasted and primed with DP40 which is a 2k primer(not sure who makes it).

there is still some old paint and bog under the primer but they couldnt blast it all out because it may have warped the panels.

should i strip those areas back with a 3M clean and strip wheel then use spartan deran A (or similar) then put the bog on before re-applying more DP40?

Edited by the gts, 25 March 2008 - 09:47 PM.


#47 Com_VC

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Posted 26 March 2008 - 10:06 AM

When I get to the compounding stage (about a week later) Do I just sand the clear coat with 1500 wet and then apply the polish? Have you had any experience with car lack? http://sitenshop.com...trashine_com_au

Also is compounding the same as polishing?

Thanks

#48 _Bomber Watson_

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Posted 26 March 2008 - 06:35 PM

The GTS: Mate, if your going all out like that you may as well take the extra time to get the rest of it out. Your plan sounds pretty much spot on.

Com VC. Mate, never seen that car lack polish before, not saying its no good, but if your going to use it make sure it doesnt have any silicone in it.

Compounding and polishing are sorta the same and sorta different. Same as undercoat and primer are two different things.

Compounding is a coarser medium used to bring up the initial shine, polishing retains that shine with a finer medium.

Use something like Meguires Ultra Cut compound at first, then go to Meguires Show Car glaze, or something along those lines. Like i have said just make sure they dont have any silicone in them. Those ones might, im not sure. I have never used them on fresh paint so have never bothered to check. In a month or so s time use Meguires Gold Wax.

Yes i like Meguires, im not that biased, i just find all there products give a fantastic finish. The only polish i use Thats not Meguires is Purple for my shiny metal things....

Cheers.

Edited by Bomber Watson, 26 March 2008 - 06:38 PM.


#49 _rorym_

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Posted 26 March 2008 - 07:34 PM

^^ Love that Man! :clap:
R

#50 _Bomber Watson_

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Posted 26 March 2008 - 09:56 PM

Actually R, its because of your obsession with Purple that i got a bottle and tried it.

Me and Ads have since discovered the ultimate secret. 7" buffer, on slowest speed, double sided woolen buff pad, put purple and water on the pad and run it all over aluminium. COMES UP f*ckIN EXCELLENT!!!




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