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Part 1: Preparing bare panels, priming and surfacing Tutorial.


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Hi all,

 

Well I promised I would write a tutorial for some of the guys on the forum with regard to my bare metal preperations and application of EP (Epoxy Polyester) primer.

 

Now I know that many will find this very basic and boring, however the guys who asked for it and many who may read it may not have had the experience of having tackled something like this previously.

 

I have written it in a way I would have used to explain the process to one of my first year apprentices years ago, very simple step by step instructions and pics.

 

If anyone finds this useful I will go the next step with application methods and material types followed by surfacing techniques.

 

Please wait till I load all of the instructions and pics in this thread before adding comments, I will write END OF PART ONE after the last is loaded, then you can all start throwing knives.

 

Cheers

 

John

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Part 1

Preparing bare panels.

 

Any restoration is only as good as its preparation, as I would often say to my apprentices, that extra 5% during pre-paint constitutes 80% of the finish quality.

 

The following is a step by step tutorial on achieving a solid base as far as pre-paint preparation, there are numerous opinions and methods used by the DIY restorers and these differ greatly from what may be executed in a fully equipped panel and paint facility, these steps are the ones I undertook in order to achieve the best possible results within a home garage environment.

 

Work Area.

 

Most DIY restorers will have access to limited space, and limited equipment, fully filtered and environmentally controlled areas are a rarity, when conducting this type of work its important to consider not only your own safety when dealing with hazardous chemicals and equipment, but also those of your immediate surroundings, family and neighbours, your local municipal officer could put a quick end to your restoration ambitions so take all this into account before commencing.

 

Equipment.

 

One of the biggest mistakes I see the DIY restorers make is their choice of compressors and application equipment, many people run noisy temperamental 2HP air compressors that make a racket, but more so the problem with these units is the fact that they cycle very hard due to their low volume capacity.

 

What happens then especially on humid days is that the compressed air collects in the tank and condenses into water which eventually makes it through the airline, the gun and into the material being sprayed, you wont notice it until long after the final spray job has been applied and the finish develops blisters.

 

The other problem with compressed air is that the material coming out of the spray nozzle is highly atomised, and you end up spraying in a cloud of floating particles that eventually come to rest on every surface in the work area, that’s OK if you are using a single Pac as opposed to a 2K material as the mist will dry before it settles turning into dust, but 2K will land as fall out and end up bonding to a surface.

 

So, your $199.99 2HP compressor from Bunning’s ends up being a bit of a very noisy, very loud, temperamental liability, what’s the alternative.

 

Well may you all laugh, but the best alternative to counter all these problems  in a garage environment is something simple like one of these, it’s a little beaver reverse vacuum spray system, it draws air in via a filtration system and basically uses that air to then deliver the material via the spray gun, very portable, as loud a small vacuum cleaner, no chance of condensed water particles making it into the sprayed material, minimal if no overspray, and perfect for the delivery of heavy concentrated primer fillers, this item was sold on EBay for $73.99, mine is a blue one but I nabbed this pic as I didn’t have one of mine.

 

I wouldn’t be using this for a final finish, although there are people who have with great success, but when it comes to priming up a vehicles I honestly cant go past it, and just how well it does the job will be revealed later.

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When it comes to panel preparation, even the best industry tools will do you little good if you don’t have the attitude from the start that the preparation of panels is like pouring the foundations of a house, you cant build on something that is sub standard and expect everything added on top will somehow conceal what’s underneath, simply it wont.

 

For panel preparation you need only very basic items that used correctly will not devastate the surface but achieve a viable good base.

 

The following are what were used for this tutorial in the preparation of panels.

 

#1 This is a heavy duty wire brush designed to really attack heavily ingrained surfaces, I usually hit smaller areas with this first, not every part of the panel.

 

#2 A medium wire brush used on a drill perfect for curved areas such as arches etc.

 

#3 A lighter wire brush used for seam areas where 2 panels meet to work away any material deposits.

 

#4 A Nylon based brush wheel that is used on seam areas as a final prep to rid the area of any remaining matter or rust deposits.

 

#5 & 6 I rarely use these, but occasionally you need to just hit back a sharp like a spot weld or jagered edge so rather than a grinding wheel these flap wheels do the job, the Scotch Brite wheel may come into play on a surface that may just need a quick run over to remove a small remnant of paint material in an obscure place where non of the others is appropriate.

 

#7 A good orbital sander is a must for flat panels, this Makita unit uses a rubber pad that allows the use Velcro sanding discs, I prefer these as the self adhesive types tend to come flying off after a while and become Frisbees, for panel prep, I use 180 grit discs which provide a workable smooth surface for primer application.

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The panel.

 

This panel was soda / garnet blasted some 4 months ago, over that time it

started to deteriorate, the effects of moisture, bare hand handling, overspray

from doing the undercarriage, and weld spit all had their effect, and apart from

these factors, not even blasting can totally rid the surface of every last form of

foreign matter, the following 4 shots show the extent of what had to be prepped.

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Once all these areas have been attacked, I move in on the remaining seams with the Nylon brush head.

 

If your paint job is going to start to crack due to bad adhesion, these are the most likely places, even if a seam sealer is put down before hand it will only adhere to the surface as well the prepped metal will allow it to do so, remember 5 minutes extra spent here will save you anguish down the track.

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Flat panels.

 

Here on in it’s a case of hitting the remaining flat panelled areas with the orbital, the following points are a must when using one.

 

#1 Do not ever hold the sander in one spot, this will only cause the machine to heat that area, and stall the orbital action.

 

#2 Never use the edge of the machine pad angled to a panel, this will only destroy the paper and the pad it is affixed to causing the pad to delaminate and costing dollars to replace, this was the reason for using the brush heads first on odd shaped panel areas.

 

#3 The paper should always orbit freely, use long sweeps with adequate pressure to allow it to do it’s job, pushing down on it to the point it stops doing what it was designed to is a waste of time and effort, let it do the job, you just tell it what direction to move in.

 

If you follow these rules, the paper once used should come of the pad looking the same as it did when put on, clean and undamaged albeit worn down to a finer grade, the resulting panel should look something like the following pics.

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In this last photo, you will notice I have red circled 2 area’s, and will also note that there is a burring effect on the metal, these are 2 area’s where I managed to metal finish some dents, as I filed them down, there were small files grooves left that non of the wire brushes could totally penetrate to surface the metal.

 

Here I used the nylon wheel to surface and penetrate those grooves, leave nothing to chance, just like a Million dollar machine that has a $0,05 nut fail and destroy it, so can one of these contaminated file marks.

 

 

END OF PART ONE

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Thanks guys,

 

As I have always said, nothings hard, but sometimes ppl SH*T themselves, a little bit of direction always helps.

 

That 1/4 took me just under 3.5 hours to prep and was masked up and locked up in primer within the next 3 hours in case anyone was wondering.

 

Cheers

 

John

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and was masked up and locked up in primer within the next 3 hours in case anyone was wondering.

 

Will this be part 2............................. in 3D????;D

 

No seriously, I like to see the whole trilogy done just like you have above please.

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  • 1 month later...

Sorry to say, but yes it would be, angle grinders run at about 16,000 RPM from memory, the orbital I have has a variable setting of 4,000 - 10,000 rpm and I run mine at about  half maximum or 5,000 rpm.

 

Hopefully I will be doing part 2 of this tutorial as soon as I get the G-Nose out of the way, so stay tuned.

 

Cheers

 

John

 

 

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  • 4 weeks later...

Great writeup Sirpent. I have to assess my funds but I may be looking at buying a decent compressor and mig soon.

 

You say that the $200 2hp ones are noisy and no good, what would you recommend for doing top coats? Bunnings has a 2.5hp belt driven compressor for about $350. Not sure on tank size but it did look slightly larger than those on the cheaper ones. Is this still too far on the low end? What should I be looking for?

 

Also can you recommend a decent welder? Edit just fond this post from Lurch:

+1 for the Gas MIG. Amperage between 185 to 200amp.

Don't skimp! Spend $1000-$2000 on a good quality name brand unit. I love Lincon Electric.

Don't get a 2nd hand unit - you may not know it's history...

 

 

Eagerly awaiting the 2nd part as well :)

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OK,

 

Look the small units can do it, its just that they will cycle almost continuosly to replace the air you are putting through the gun, apart from them over heating, the air coming out of them condenses into water droplets or mist as part of the paint you are laying down which will eventually mean humidity blisters in the paint work down the track.

 

If you have to buy one of these units, then invest in a good water seperator at the tank hose outlet and also a smaller inline one at the gun hose inlet, this should almost totally address any posible contamination in the paint.

 

Cheers

 

John

 

P.S. Lurch is 100% spot on with the mig, I spent $250.00 on a gasless job and it only just does what I need it to, should have spent the rest and got one for life for every job I could ever consider.

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