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 Post subject: Re: DIY Spraying
PostPosted: Wed Sep 25, 2013 11:15 am 
Retro Guru
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Joined: Sun Aug 01, 2010 1:04 pm
Posts: 2501
Location: West Sussex
Great result. I shall be reading with interest as I'm looking for a kit myself (got some fancy GT paintjobs to touch up).

I notice your sprayer looks a bit industrial (fine for cars). If you look on Youtube there are some great vids of cheap Chinese copies of expensive detail airbrushes (available on ebay).

People on here are always going on about powder coating, it's fine if you want to paint a childs swing or a washing line. But as you say it lacks the WOW-factor. Good luck.


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 Post subject: Re: DIY Spraying
PostPosted: Wed Sep 25, 2013 12:48 pm 
retrobike rider
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Joined: Tue Jul 14, 2009 7:52 pm
Posts: 1904
Location: Trancecentral
The compressor is a little ott for airbrushing, but what will do a lot will do a little.

The gun is a mini HVLP gun and works great, the spray fan being about 2in how I have it set. I run it at 40psi from the comp. It's not a full sized gun. If it wasn't with the sale I'd have picked up a touch up gun for the bike painting.

I saw the copy airbrushes, about 20 quid, that's what I'll buy, with a tee junction and a regulator moisture trap for the airbrush line. Can't justify a badger airbrush.

For just airbrush work an eBay Jun-air compressor would be my choice. To keep it quiet.


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 Post subject: Re: DIY Paint Spraying
PostPosted: Thu Sep 26, 2013 5:51 pm 
retrobike rider
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Joined: Tue Jul 14, 2009 7:52 pm
Posts: 1904
Location: Trancecentral
Part 4.

I've sanded down the 1st primer coat on the frame.
I did this using P2500!! wet n dry because that was all I had. Using a water spray bottle to keep the frame wetted and to wash off the wet n dry.

The spray bottle worked well to also show the areas that had been sanded, as you can see in the pics, the smooth areas the water ran right off. A few areas I can now see where the 1st primer coat was thin. I guess it'd be much more important for coverage on a steel frame.

Next stage will be 1st coat of primer on the forks, 2nd coat of primer on the frame and bars. I'll try a light dusting over the thin areas that have now been highlighted by sanded and then an overall 2nd coat.

Downtube sanded, toptube not:

Image

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A couple of thin areas:

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 Post subject: Re: DIY Paint Spraying
PostPosted: Sat Oct 05, 2013 8:10 pm 
retrobike rider
retrobike rider
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Joined: Tue Jul 14, 2009 7:52 pm
Posts: 1904
Location: Trancecentral
Part 5:

I've sprayed the forks with primer, sanded those back and then sprayed the forks/frame/bars again.
I gave them a blow over with the gun, to provided a very slightly wet surface.
I then sprayed the whole lot a good 3 coats of primer. I changed the fan from vertical/horizontal/45 deg. depending on which tube or area I was painting. I'd spray from off the frame, down the tube and straight of the end of the frame. Actuating the trigger at each end with just air before adding paint again. I overlapped the length of the spray with the last about 50%.
I gave it 10 mins between each coat.
The finished primer looks very good with no runs. There is a texture to the primer now, looks like it's built quite high. I'll let this dry as I painted outside, not ideal and not warm. I'll then sand this back to smooth and tackle, dah dah dahhh, a colour coat.

I guess the easy bit is done.

Next steps.
Sand primer. Clean frame, I bought some panel wipe £10 for 5ltr.
Decals? Would need to add a colour coat in the decal areas, make a vinyl decal to use as a mask before adding top colour coat.
Or, final colour and thin vinyl/water slide decals before clear coat.

The texture of the primer does look really good, make me wonder about textured finishes, spray colour without sanding primer, would this show the texture? And then clear coat, sanding that to flat between coats. Smooth clear over textured colour. maybe on another frame. One step at a time.

Some pics:
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This spraying is fun and addictive!


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 Post subject: Re: DIY Paint Spraying
PostPosted: Sat Oct 05, 2013 9:29 pm 
Old School Hero
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Joined: Sat Feb 28, 2009 12:51 pm
Posts: 201
Location: Plymouth uk
top marks for giving this a go!

try and spray the paint a bit more wetter,less air pressure ,and you wont get the textured finish so much.
be a little bit brave!
maybe practice your finish on a practice panel to get used to the gun.
your actually spraying it textbook.you have done your homework thats for sure
its ok spraying primer and spraying it dry,but you definitely wont like the textured finish in your top coat .

go for it!


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 Post subject: Re: DIY Paint Spraying
PostPosted: Sat Oct 05, 2013 9:43 pm 
retrobike rider
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Joined: Tue Jul 14, 2009 7:52 pm
Posts: 1904
Location: Trancecentral
oldschoolfool wrote:
top marks for giving this a go!

try and spray the paint a bit more wetter,less air pressure ,and you wont get the textured finish so much.
be a little bit brave!
maybe practice your finish on a practice panel to get used to the gun.
your actually spraying it textbook.you have done your homework thats for sure
its ok spraying primer and spraying it dry,but you definitely wont like the textured finish in your top coat .

go for it!


Ahh, I'll turn down at the the gun, thanks for the tip. I only have the gauge at the compressor for now, I set that at 40psi, the gun says use under 45psi.

Is it possible to sand this primer too smooth? Will the paint adhere via chemical or will it run?

I guess runs, or lack of, are all down to technique and practice, and correct mixture of hardner/paint/thinners.


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 Post subject: Re: DIY Paint Spraying
PostPosted: Sat Oct 05, 2013 10:10 pm 
Retro Guru

Joined: Wed Apr 24, 2013 10:17 pm
Posts: 652
Location: worcester
good work!

I spray cars for a living and spraying bike frames is one of the hardest things to spray and get a good finish with no runs!

I wouldn't flat primer any higher than p1500 in case the base/2k top coat won't adhere properly.

try and spray at about 26 is deg as the paint will dry quick enough to prevent runs but if its too hot the wetness of the finish will be affected!

Kyle


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 Post subject: Re: DIY Paint Spraying
PostPosted: Sun Oct 06, 2013 4:33 am 
Retro Guru
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Joined: Fri Jan 13, 2012 2:28 am
Posts: 1060
Location: Near Gatwick
stewlewis wrote:
Is it possible to sand this primer too smooth? Will the paint adhere via chemical or will it run?

I guess runs, or lack of, are all down to technique and practice, and correct mixture of hardner/paint/thinners.


I wouldn't go any finer than 800 for base coat and 600 for solid.
I started dry sanding recently, not that I paint very often these days, I used either P320 or P400 and it was great with solid 2K black and with the red clear over base on my bike.


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 Post subject: Re: DIY Paint Spraying
PostPosted: Sun Oct 06, 2013 11:34 am 
Old School Hero
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Joined: Sat Feb 28, 2009 12:51 pm
Posts: 201
Location: Plymouth uk
800 - 1000 grit is ideal
maybe use some scotchbrite for the tricky parts of the frame like the welds etc
like Kyle said, they are tricky to spray.
Maybe practice on an old frame first before you topcoat


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 Post subject: Re: DIY Paint Spraying
PostPosted: Sun Oct 06, 2013 6:04 pm 
retrobike rider
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Joined: Tue Jul 14, 2009 7:52 pm
Posts: 1904
Location: Trancecentral
Many thanks for all the help fellas.

Part 6:

I sanded down the frame/forks/bars with 1000 w&d.
Keeping it very wet and washing the paper often.
Washed off and then wiped down with panel wipe.

Lesson learned, get the primer coat smoother from the gun, sanding is time consuming, sanding is bad.
Will pick up some scotch pads. Can these be used instead of w&d, are then any better for round tubes?

Now I think I've messed up, with my paint mixing.
When I bought the kit the guy game me paints:
Primer/Primer hardener
Colour
Clear/Clear hardener
Uni thinners.

The primer said on he tin: 4:1 + 30%
I mixed 4 primer:1 primer hardener:30% thinner.

The colour, not having any hardener, I didn't add any at all. Have I ballsed this right up?
I just mixed paint, with some thinners until it was very thin, about 3:1 I'd say.

So I had a go at spraying some colour, on the forks and the bars.
Again spraying outside, which is far from ideal. Lesson learned, if you think it isn't windy, you're wrong.

I added a quick release to the gun, apart from the quick release the coupling alows the gun to twist on the hose, £3 well spent.

I sprayed a fine mist of a coat and let it be for a few mins and then I spray around the awkward bits, drop outs, brake mounts, inside welds etc. with the gun patter set to spot.

After a few mins I then sprayed vertically with the pattern set to horizontal fan, trying to keep parallel to the target and overlapping on the up and down strokes. The paint went on brilliantly, I kept moving and got no runs. I gave it 10 mins between coats and did 3 full coats. It's looked really good.

It dried with a slight texture. Slight to the touch, the pics really highlight it, it looks better to the eye, the highlights and macro really show up the texture.

The finish is good and I'd be happy with it on a bike for a DIY job. Way better than I ever got out of a can. But this is my practice piece, trying to get a glass finish :)

So, question time:
My setup is far from ideal, is the outdoors just causing me too much grief?
Thinking about getting a spray tan tent for the garage.

I adjusted the air pressure at the gun control, it didn't seem to make much difference until it spluttered too low. Cheap gun maybe? Should I get an inline valve reg as I'm relying on the compressor set at 40 over the 10m hose, should the gun just put 10psi at the cap no matter what it's fed?

Colour coats. How many? Should I thin down more for final colour coats?

How can I polish/smooth this colour coat now? Is it possible or will I go straight through and need another colour?

I appreciate the help, as a give it a go guy, says a lot about this great forum that I wasn't told to get lessons/join a painting forum/take it to a pro...etc.

The latest pics:

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