good afternoon
we will start soon
the prodution it will be around 150 pieces by day( table tops, shelfes,sides etc). some pieces have 80m/m high 2000m/m lengh 400m/m width.the spray will be airmix or airless(?)kremlin.
peices are fibreboarb with uv sealer( 2 coats) and 1coat of primer pu, if we need and pu top coat both sides.
how to avoid overspray in the back side without covering all area(back).
coler will be white,black, red
any comments
thanks.:thumbsup:
For that kind of quantity I can tell you what I've gone through. First off, you can't do that much in your driveway or backyard for many reasons. You'll have neighbors complaining about overspray and fumes for a half a block, not excluding the numerous cars that will not be completely painted. Next is contaminants that float or drop on the work. Even in a shop setting that is all set up with an appropriate spray booth, you may have complied with fixturing and laws of your state, but there are also local municipalities that can give you more grief than you'll ever need. In addition (at least in Florida) to all that you will need a HAZMAT certification that is posted.
High gloss colors can be done several ways. Lacquer finishes dry fast, but it's difficult to get an "off the gun" gloss that needs no polishing. For small pieces, a suitable substrate sealed, and color sprayed, may need to be wet sanded to very smooth abrading to 1200x to 2000x depending on your buffing and polishing equipment. In the polishing, there are several compounds that range from a very coarse pumice to an ultra smooth paste/liquid that leaves no marks. This works if you have the time and are willing to go through several steps to a finish.
Or, you can use a straight automotive paint in a color. It works best with a smooth substrate that has been primed with an epoxy based primer, some have adhesion promoters. You can get a very good "off the gun finish", but laying out a coat without any orange peal or runs is very difficult. If that finish is wet sanded and buffed, that finish will appear totally different than the "off the gun" coat. So, you can't rub out one section and have it look like the rest, it all would have to be rubbed out.
One of the quickest finishes would be an automotive base coat, clear coat. With that, you still should prime/seal the substrate. Your color coat doesn't have to be perfect. The clear coat can be applied that may or may not need any sanding or buffing. That would depend on how good you are and the equipment you are using.
The color polyurethanes can be very pricey, but some can give very good "off the gun" finishes. There are many types of applications that are catalyzed that offer a faster dry time, but ideal conditions and technique are key to good finishing.
As for equipment, a large enough air delivery system that gives fairly cool dry air to the gun will produce a much better finish than one with questionable filtering and moisture extraction. I posted
this thread about blushing and air system problems, that may be of some help.
For spray guns, almost any material can be sprayed from an ordinary syphon cup type. That's all I used before HVLP became available. You can get very good finishes with them. An HVLP will reduce the amount of material used and provide a much better transfer efficiency with very little overspray.
To answer your question on reducing overspray on the backs, I try to hang the piece from an unseen edge so I can spray the whole piece at once. For example, upper cabinet doors I would hang from a small eye hook in the top of the door, and likewise the base doors would be hung from the bottom. Or they can be hung from one of the screw holes if you have prehung the door or have already set it up for hinges. But in figuring other pieces, the layout time and finishing of one side at a time uses up space and is very time consuming. For flat stuff, I may lay them on a table on top of some spacers to just get the top surface or the top surface and the edges.
Very large production of finished pieces are usually done by an electrostatic process, where they are charged electrically and passed through an atomized booth and the surface collects just the right amount of finish.