Spray painting

Currently reading:
Spray painting

Joined
Jun 26, 2008
Messages
3,212
Points
517
Location
Hampshire
I'm new to all this, so need some help.

Guns - I have a suction feed spray gun. 1l pot but the pipe inside doesnt reach the bottom. problem? I wont be doing whole cars, more liekly to be the odd panel or so. Would a gravity fed gun be best? I guess both have their ups and downs.

I only have a 24l 8bar compressor, so I presume some guns will require to much pressure.

Paints - Seen this mentioned in a few other threads.

I understand that cellulose mixed paints are fading out due to it being bad for enviroment, and 2K being dangerous unless you dont have the right breathing equipment.

Waterbased seems a good sensible option, but can you use 1K primer and laquer? take it 1K isn't as bad as 2K?

Mixing - How do you know how to mix the right amount, buggered if you do to little and wasting if you mix to much. Is there a calcualtion for working out paint volume to surface area of piece being painted?

Perhaps someone could do a guide on this. Be useful for many I expect.
 
I'm new to all this, so need some help.

Guns - I have a suction feed spray gun. 1l pot but the pipe inside doesnt reach the bottom. problem? I wont be doing whole cars, more liekly to be the odd panel or so. Would a gravity fed gun be best? I guess both have their ups and downs.

It is all about personal preferance, some prefer the conventional suction feed, the gravity ones are more efficient though and are cheap.

I only have a 24l 8bar compressor, so I presume some guns will require to much pressure.

Steer clear of HVLP guns they require a lot of inlet pressure, with your compressor look at a gravity fed non HVLP gun.

Paints - Seen this mentioned in a few other threads.

I understand that cellulose mixed paints are fading out due to it being bad for enviroment, and 2K being dangerous unless you dont have the right breathing equipment.

Waterbased seems a good sensible option, but can you use 1K primer and laquer? take it 1K isn't as bad as 2K?

Cellulose has not been used in ages, except on some commercial vehicles. it was an all in one paint type. It is not as strong as 2k paint systems.

1k paint is what you find in spray tins. It is good but the lacquer is not tough enough to do bonnets or roofs very well.

2k so called because you mix the paint with a seperate hardner hence 2x parts. It is the muts nuts. It is very tough, I use 2k lacquer as it gives a much tougher gloss finish.

Waterbase. This is used mainly as base coat although primers and lacquers exist. I use 1k or 2k primer, water based base coat and a 2k lacquer.
The beauty of waterbase is that it can be bought pre mixed and you can simply wash guns out with water, in essence it is emulsion. You will need a waterbase gun though as it will rust a gun out.

Mixing - How do you know how to mix the right amount, buggered if you do to little and wasting if you mix to much. Is there a calcualtion for working out paint volume to surface area of piece being painted?

Perhaps someone could do a guide on this. Be useful for many I expect.

This is where I love the waterbase, being premixed you simply tip excess back into container.

1k is usually mixed 50/50 paint to thinners.
waterbase is mixed with 15-20 percent water
2k lacquer I use neat. but 10 percent thinners can be added depending on product. the hardner lacquer ratio is 3parts lacquer 1 part hardener- same applies to 2k primer
knowing how much to mix comes with practice. ;)
To mix you buy mixing cups.

Hope this helps. I will put a guide up if needed, im spraying my mx5 soon.
 
Last edited:
Thanks Bridges. I found a company(automotive paint supplies) local to work so i'll pop down at lunch time and quiz them. Mixing cups i can buy on Ebay in packs of 10/20 so easy enoguh to get as well as mixing sticks if required. I'll see about getting a gravity fed waterbased gun.

Would 1k primers be available in a "tin" for use in the spray gun?

How do you go about cleaning a gun after use with laquers/primers/paint? so not to contaminate the next media in use. Can you just blow through or wash through with water. I guess this would be ok if I have a waterbased gun.
 
Steer clear of HVLP guns they require a lot of inlet pressure, with your compressor look at a gravity fed non HVLP gun.
.
the opposite,
HVLP = High volume low pressure - this is what craig wants

craig you will want hvlp gravity feed i think, ill give you a pm on here when im all set up with my kit you can come have a look if you want? :yum:
(i think our budgets/compressors are similar)

cheers,
Matt
 
Been down to the Paint shop and wanted £128 for 1l mixed waterbased. trade price too. then an extra £119 for 10l of laquer.

Extorionate if you ask me. perhaps i'll look else where. any online recomendations?

i was recently reliably informed to go with OB primer : 2 parts primer 1 part thinner and

cellulose straigh colour if your a nervous beginner (thats me and you)

2k 2 pack laquer for the best finish (its more difficult to use apparently but more rewarding) i might give this a go.

£120 for a litre is total insanity
i was advised to aim for £20-25/litre of 2k +2 pack laquer

:)
 
the opposite,
HVLP = High volume low pressure - this is what craig wants

craig you will want hvlp gravity feed i think, ill give you a pm on here when im all set up with my kit you can come have a look if you want? :yum:
(i think our budgets/compressors are similar)

cheers,
Matt


Wrong, wrong, wrong! :p

HVLP= High Volume Low Pressure at the gun outlet not pressure inlet ;)

A conventional spray gun may have an inlet air pressure of say 60psi
the spray exiting the gun will leave at around 50psi

A HVLP gun uses higher inlet pressure it uses this higher pressure to mix the paint in the gun into a finer mix. The exiting pressure is only around 10psi
The purpose of HVLP is to reduce overspray, they are more efficient in getting the paint onto the panel.
 
Been down to the Paint shop and wanted £128 for 1l mixed waterbased. trade price too. then an extra £119 for 10l of laquer.

Extorionate if you ask me. perhaps i'll look else where. any online recomendations?

10l is a lot of lacquer. I would reccomend buying it in around 1L quantities if spraying odd panels.

I buy 5l lacquer and 2.5l hardener making 7l for £50 from a paint store that mix their own and it is awesome.
waterbase is around £80 a litre for the top grade stuff (dupont) so £128 is daylight robbery.

2k is cheaper, or you could use a 1k base coat. remember 2k is toxic.
 
Last edited:
the opposite,
HVLP = High volume low pressure - this is what craig wants

craig you will want hvlp gravity feed i think, ill give you a pm on here when im all set up with my kit you can come have a look if you want? :yum:
(i think our budgets/compressors are similar)

cheers,
Matt

sorry but bridges is correct, see my thread in this section, i have just had to upgrade compressor because the budget compressor dose not have enough omph for a hvlp gun
 
Just a thought, but I was told you had to post cure water based paint in a oven, or use a hair drier on smaller parts before putting on a lacquer.

Am I right or wrong?
 
Just a thought, but I was told you had to post cure water based paint in a oven, or use a hair drier on smaller parts before putting on a lacquer.

Am I right or wrong?

Right (y)
water based paint is as near as can be, emulsion.

You can get special water additives to mix with it that are supposed to evaporate it quicker, but I have found these to be rubbish.

To dry you want air flowing over the painted surface, warm is better. heat alone will not dry so well.

I was recommended by a very good sprayer and have since and now always use, a hairdrier. (ideally you want a new one to not get bits of contamination in the paint) I dry each coat before application of the next coat. a wing would take say 2 mins to dry :)

Quality of paint makes a massive diference to drying time too.
 
I would use a gravity fed gun with your compressor as it won't require so much pressure. I prefer to use cellulose personally but synthetic is much more forgiving.

Don't forget that if you spray cellulose over synthetic your will need to use an alchohol based sealer first.
 
I don't get into all of the scientific stuff. I use a gravity fed gun and you can just use the spray gun to blow the paint dry for abit or use a heat gun if you have one, it works for me.

I also use 2k lacquer and thinners and i never had a problem with it.
 
Wrong, wrong, wrong! :p

HVLP= High Volume Low Pressure at the gun outlet not pressure inlet ;)

A conventional spray gun may have an inlet air pressure of say 60psi
the spray exiting the gun will leave at around 50psi

A HVLP gun uses higher inlet pressure it uses this higher pressure to mix the paint in the gun into a finer mix. The exiting pressure is only around 10psi
The purpose of HVLP is to reduce overspray, they are more efficient in getting the paint onto the panel.

sorry but bridges is correct, see my thread in this section, i have just had to upgrade compressor because the budget compressor dose not have enough omph for a hvlp gun

wow ok....well im in the **** then!

could you do a pros/cons list for hvlp and what i can only assume will be called lvhp? :D

will my 25l 9.5 cf/m have the balls to handle a hvlp gun?
 
I have found a conventional gravity fed gun works best for me. I've sprayed all kinds of things recently from old synthetic truck paint, hamerite, zince paints, creasote, 2k (with a decent mask) but not cellulose recently. To set the gun up, tape some newspaper to a a vertical surface and adjust the gun with some tests to avoid runs on your target article. The most recent thing I've been spraying is my garage door and a fence. I bought a £400 belt driven compressor which seems to produce enough air for an HVLP but have found the conventional guns chuck out a bit less paint and therefore less risk of runs which is the problem I always seem to have.
 
Back
Top