Reducing The Loss Of Paint During Spray Painting

If the parts are small or a bad shape for spraying .. can you dip 'em instead?

Aren't there ways of using electrostatic charge to get the paint onto the piece rather than onto the wall?

Del

please explain

If the paint gun is postively charged, and the work piece negatively charged, the paint spray will get attracted to the work piece. I think they do this with powder coatings which are sprayed on and then baked in an oven.

Try googling electrostatic spraying?

Del

Yes but this system is 2 decades old he must be aware of it. He hasen't detailed much.

Long long time in a Tannery, the sparying of paint on the hides were done in conjuction with some imported expensive oil. The spary room had to exhaust fans to extract the fumes and the client wanted to recover the oil extracted out. I designed a separator system with duct behind the exhaust fans which collected and saved the extracted oil. Being working till date since last 20 years. His is something new so I pass.

Electrostatic is a good option. However if the booth isn't originally set up for an electrostatic system it's really hard to make the booth not grounded.

We changed over to an electrostatic system and our booth had the sprinkler system (which is a solid ground source) going to the booth, the air lines, the electrical conduit all connecting to the booth along with the duct for the exhaust fans.

It didn't matter that we had the grounding wire for the electrostatic connected to the parts. The roof and and sides of the booth got more paint on them then on the parts.

What's funny is we had a production manager, who was from France, look inside the booth and see the overspray going everywhere. It didn't matter that we'd show him all these grounded connections to the booth. He'd blame the painters for not knowing what they were doing.

I would suggest sending your parts out for powdercoating. We find that we save money doing it. They charge by the pound.

It's even cheaper getting them zinc plated. We get zinc plating done at 50 cents a pound. Zinc plating is also more durable then painting. Powdercoating is much more durable then spray painting.

DO NOT DO THIS!

DANGER OF EXPLOSION!!!!!!!!!!!!!!!!!!!!!

1. Post #1 merely asks if electrostatic charge is a technique.....and indeed it is (widely used in powder coating I believe)

2. Tecspert's paint is water based.

3. One has to assume some degree of common sense as nearly all activities carry risk and a lengthy disclaimer would be required on every post. I don't expect anyone would try and set up an electrostatic system without checking out suppliers of such systems etc.

4. My Underpants have a fart warning attached as there is danger of explosion.

Del

I explained this earlier.

If the booth was not originally designed for an electrostatic system then it's pretty hard to convert it over so that the booth isn't grounded.

If the booth has a ground going to it from any source you might as well not even bother hooking the ground to the parts you're about to paint.

He should also look into sending the parts out to be powdercoated. He might find that resource less expensive then painting at his shop, especially if the quantities are large because they charge by the pound and usually have a minimum requirement.

How about reducing the flow to the jet and reducing the cone-angle of the sprayed paint so that there is less excess? The good-value Badger and the Draper ones have some adjustment in this regard, though the more one pays for an airbrush the more adjustment features it will have on it.

-Make sure that while painting velocity of wind is normal.

-If the wind factor is there, proper arrangements shall be made to cut off the same by using barricatings.

-Material on which paint is to be applied shall be arranged properly on the bed. So that the wastage shall be minimum.

etc.

If you are using paints made from chemicals ( MEK, Acetone, MiBK, etc, etc,) you have to have the level of VOC's below a critical point, if not you may or will have flash over and possibly and explosion !! The critical point is move air !! how much, tell me the size of the space H x W x L how much you will be spraying, what you are spraying and I can give you some suggestions. Unfortunately, with spraying you have to factor in only about 70-75% efficiency. We use small tips to minimize loss as well as our coatings are 100% solids ! and we still calculate a minimumm of 75% efficiency. Hope this helps.

thanks for the sugggestion

our paint solution is water base

the size of the part is 70mmx70mmx22mm

we are spraying the formulation having glass frit water base viscosity 45cps

plz suggest

Read NFPA 33 and 91. 33 specifically deals with paint spray booths. Its about 70 to 80 pages long. 91 is shorter at about 30 pages and deals with exhaust systems for areas such as paint spray booths. You can purchase the standards online at the NFPA site. If you are going to do something with the HVAC system for a paint spray area, it is a good idea to know safety standards for it.

Hello Tecspert,

The first thing to check is your equipment. What kind of equipment are you using? Take also in consideration the experience of your painter, the air pressure they use, their application technique. 2nd thing is the paint itself: you are using a waterborne paint, what's the % of solid (in volume), is it possible to switch to a higher % of solid paint? Why did you choose that particular paint? any special requirement? we manufacture waterborne epoxy paint with 44% solid: coverage at 25 microns= 16,9 sqm/l but we do have same type of epoxy paint at 75% solid : coverage at 25 microns= 30 sqm/l

3rd is the set up of your production line (batch): is there a way you can improve efficiency? a study must be perform and maybe a better design will help. Maybe you can switch to a powder paint (with a recycling process) you can get up 95% efficiency... of course the capital investment can be recoverd quickly if quantities are worthed..

A good tech rep (from your paint supplier) should be able to give proper application technique to your painter and some tips to improve your efficiency.

To help you out more we need much more information on your painting process but with these starting points it's a good starting..

Very well said Madmax 1997 !! This is a very general question but following his guidelines is a start !! I find that most manufactures can make paint but don't know how to spray paint. You must get to know your machine, the atmosphere your in, the person painting, ( good or bad, do they know what they are doing?) etc.

Madmax stated well !!

HVLP. High Volume Low Pressure.

This is how most industrial painting is done now.

If you do not want to change your assembly to other techs mentioned by few experts like electrostatic spray painting , you can change the way you paint , what kind of spray do you utilise , there new spray guns available that have fine focussing , continuous recirculating medium .

I'm surprised nobody has mentioned water (well liquid) curtains?

I have no experience I hasten to add.

Still can't help thinking:- water curtain...water based paint....