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 Post subject: DIY Paint Spraying
PostPosted: Tue Sep 24, 2013 12:29 pm 
retrobike rider
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Location: Trancecentral
Not necessarily retro, mods stick it in general if so.

I'm starting this thread as more of a general hints and tips for home spraying thread than a bike resto thread. Hopefully we can share knowledge of paint tips, equip and technique.

I bought a compressor off Ebay that came with a few bits n bobs.
It's this one:
http://www.machinemart.co.uk/shop/produ ... C-tiger+44
It came with one of these:
http://www.machinemart.co.uk/shop/produ ... C=SRC-hvlp

Having never used one before to my eye's it seems just fine. Bloody loud when the pump kicks in, scares the hell out of you when concentrating on a spray.

I had a quick spray with water through the gun to get a feel for the shape of the spray.

This is my test bike:
Image

The lacquer is rough and it has a few scratches:
Image

Image

The DMR Sidekick forks are (bloody heavy!) and kind of a lacquered ano green. I still have to learn about finishes.

From what I've read preparation is everything. I spend an hour sanding the sanding the frame to remove some lacquer with 400 grit wet n dry. This was taking ages so I bought some paint stripper:

Image

Cheapest I could get from Homebase, £10

This stuff worked a treat, was quicker on the frame having scuffed the lacquer with the 400 grit. The forks took a while longer as the lacquer was in good condition. It work though, peeling the paint off like a skin.
I scrubbed at it with a stiff plastic brush then washed it off with a brillo pad and the hose. The brillo worked well around the welds.

I missed taking pics! I then sanded the frame with 600 wet n dry to key for the primer, I didn't know what type of primer I had whether it was etching or not, it came with the compressor. The frame didn't have any deep scratches, the others sanded out well enough, for a test bike.

The forks, post paint stripper, before final bare metal sanding. The ano? coat came off with the brillo pad:

Image

Image

Next I decided I'd paint forks, frame and bars. Red, I had some red that came with the kit...


Last edited by stewlewis on Thu Sep 26, 2013 5:40 pm, edited 1 time in total.

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 Post subject: Re: DIY Spraying
PostPosted: Tue Sep 24, 2013 12:40 pm 
retrobike rider
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Location: Trancecentral
Part 2:

I cleaned the frame, a good wash and then a wipe over with paper towels and white spirit.
Taking care not to touch it with skin greasy fingers, I hung the frame outside as it was wind free and sunny.

I mixed the primer:. 4 parts paint, 1 part hardener and 30% thinner. This was made easy with paint measuring cups.
Stuck on the mask:
http://www.machinemart.co.uk/shop/produ ... respirator

and had a spray, working rhythmically, past the end of the frame and spraying only air through the gun at the end of each stroke I built up the primer and this was the result.

Image

Image

Image

Image

Image

Image


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 Post subject: Re: DIY Spraying
PostPosted: Tue Sep 24, 2013 12:44 pm 
retrobike rider
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Location: Trancecentral
Part 3.

The frame look OK, to my eyes. There are no scratches visible and no runs.
I don't know if I have enough paint on the frame, there are a couple of thin areas that were on the underside of the hanging frame.

Spraying is fun! Easier and much more controlable than rattle cans. Every time I've used cans it's been haphazard and cost a bomb.

The primer has a slight texture to it.

Question: Do I now wet sand at this stage to a smoother finish, 600 grit? Or will the paint smooth out this slight texture?

Question: Do I spray a guide coat of colour before a sand to highlight and high and low points? I can understand this with a flat panel but a round tube with many different angles I'd wonder about taking off too much.


Last edited by stewlewis on Tue Sep 24, 2013 12:53 pm, edited 1 time in total.

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 Post subject: Re: DIY Spraying
PostPosted: Tue Sep 24, 2013 12:51 pm 
Anglian Deputy AEC
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Location: Livin' in a dust bowl
It's much cheaper to get it stripped and powder coated plus you get a better, more durable finish. Just my opinion.

Just seen you mentioned wiping it down with paper towel and white spirit. White spirit is very oily - used to thin oil based paints etc. Get some proper panel wipes!


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 Post subject: Re: DIY Spraying
PostPosted: Tue Sep 24, 2013 1:03 pm 
retrobike rider
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Location: Trancecentral
My reason for spraying is a desire to learn and hopefully get creative with different finishes.
I've had bikes dipped and powdered before, I agree it's durable but at a budget coaters a little thick and just not a wow type finish. The coat I had was white and I didn't wet sand it at all, the scratches now on the powder coat just seem very obvious when they get dirt into them.

I'd like to get spraying done OK and then have a play with an airbrush for some designs.
I want to get the basics sorted as a good foundation.

I did the wipe over with a brush cleaner I had knocking around, it was called Clean Spirit, don't know what was in it. It didn't leave have noticeable effect on the primer coat.
I thought about using some of the 2pk thinner, but that's well smelly.

I'll pick up some wipes, for now I'm using whatever I have as I'm being a cheap git.

I've read a lot online, regarding paint ratios and how many coats, as always there's lots of differing 'rules'. I read a paint finish being very durable if, not laid on too thick, thin paint adhering and drying better.


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 Post subject: Re: DIY Spraying
PostPosted: Tue Sep 24, 2013 2:25 pm 
Gold Trader / PoTM Winner
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Paint wont take out the texture of the primer... (well, it might, eventually, given enough coats, LOTS of excessive rubbing and flatting, and EVEN MORE luck!!!)........... that looks like a high build filler primer....
I would gently rub down with 800 first, to see whats going on with the primer and how thick it is. 600 might be a bit too harsh and you could go through, especially on a frame where there are lots of pressure points (basically corners, radiuses and edges... flat panels are much easier to rub down)


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 Post subject: Re: DIY Spraying
PostPosted: Tue Sep 24, 2013 2:39 pm 
retrobike rider
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Location: Trancecentral
Cheers, will smooth it with some 800 wet. Would a high build primer be correct for a bike? Is the point of high build to cover imperfections that are not worth filling.

Will update with the next step.


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 Post subject: Re: DIY Spraying
PostPosted: Tue Sep 24, 2013 2:51 pm 
Gold Trader / PoTM Winner
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stewlewis wrote:
Is the point of high build to cover imperfections that are not worth filling..


Yep... I'd still use it on a bike frame however, as its so easy to "go through" becasue of all the pressure points.
I would steer well clear of braze-ons and cable stops with the rubbing tho... stick to the tubes and flat surfaces



G


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 Post subject: Re: DIY Spraying
PostPosted: Tue Sep 24, 2013 4:36 pm 
Devout Dirtbag
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Joined: Fri Oct 30, 2009 4:36 pm
Posts: 104
stewlewis wrote:

Question: Do I now wet sand at this stage to a smoother finish, 600 grit? Or will the paint smooth out this slight texture?

Question: Do I spray a guide coat of colour before a sand to highlight and high and low points? I can understand this with a flat panel but a round tube with many different angles I'd wonder about taking off too much.


Use as fine a wet paper you can get your hands on 1200 is ok 2000-2400 is best, the colour coat will show up an imperfections you have in your primer. so get the primer as smooth as possible first.

A guide coat can help, but it is most useful on flat panels, if you take of too much you can always add a coat of primer. The primer is there to fill imperfections, it can only do that by sanding it down and then re-coating with primer, this levels the surface.

Good luck.

Simon.


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 Post subject: Re: DIY Spraying
PostPosted: Tue Sep 24, 2013 9:00 pm 
Retro Guru
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Location: manchester uk
mmmm the smell of 2k paint :D cant beat it, :D
try and stay clear of paint stippers if your repainting as it can rear its ugly head during painting if you dont get it all off and invest in some panel wipe from your local paint supplies, its about £12 - £15 for 5 ltr much better for wiping the job down before painting. :wink:


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