Compressor and paint sprayer question

[Louis Brandt]

Hello,

I have a Craftsman 3 gallon 1 HP compressor that has served me well in use with nail guns. I need to know whether this compressor would be adequate for a paint spraying application that I need to do. The compressor is rated at 2.4 SCFM at 90 psi, with a 125 psi max.

I’ve heard that to use a compressor for spray painting, you need high volume and low pressure, and I realize that this compressor isn’t a high volume one, but let me explain what I have to paint, and maybe you’ll tell me that it’s adequate for this job.

All that I’m going to be painting is the 3 inch wide, 1 inch thick border of a large, oval mirror. After measuring the size of it, I figure that I’ll only be painting the equivalent of about four square feet. I want to use a semi-gloss latex paint.

Since I already have the compressor, I thought that it would be nice if I could use it for this job, instead of having to buy a separate paint spraying system. I will have to buy a paint sprayer for the compressor, since I don’t have one, but I thought that it might be cheaper than starting from scratch with a complete new unit.

Thoughts?

Thanks,
Louis

[Julian Wong]

Louis,
The paint job you are describing is indeed pretty small and you can get by with your compressor. There will be times when you have to wait for your compressor to catch up but you will survive. I would not make spraying with this compressor of this size a habit. Yours is not a 100% duty cycle like industrial ones. Yours is probably 25%-50% at the most.

Some other thoughts to consider. You may need to get a larger needle and cap if you want to spray latex. If you're using gravity fed, most HVLP sprayers don't do well with the standard 1.4mm tips. You will need a larger tip. 2.0mm or 2.2mm. And depending on which brand of latex paint you're using, you may need to thin it out with paint extenders. Those are additional costs.

Plus, you will have to clean the spray gun when you're done, or several times in between too if you're not spraying on consecutive coats.

My recomendation for such small jobs is to use a rattle can. 1 can should be enough for the 4 sq ft you're doing, including multiple coats. No clean up. Spray and you're done.

If you're looking to paint anything bigger than that, I'd start looking for a bigger compressor with higher output.

Then there's always the tried and true method of a paintbrush. no compressor needed ;)

[Louis Brandt]

Thanks for your reply, but I can't use a rattle can, because I need to match a particular paint color, and I can't get that color from a rattle can.
Since I've never used a paint sprayer with a compressor, can you explain what you mean by a larger tip? Are you saying that the tips of paint sprayers can be changed?
Louis

[Julian Wong]

Louis,
Yes, tips of spray guns can be changed depending on the viscosity of the material you're spraying. But most spray guns only come with 1 tip, the additonal sizes are optional accessories. And most "general use" tips are designed for thinner material and not latex paint.

I'm more farmilar with gravity fed HVLP sprayers, the cup above the tip. I don't have much experience with the siphon type, cup below the tip, so I can only speak for gravity fed sprayers.

For gravity fed spray guns, the finish needs to flow onto a needle and is pushed out to the tip with compressed air. To control flow, the size of the needle is matched with a cap (needle orifice). When you spray thick finishes like latex paint, you ned a larger needle and matching larger cap orifice for the paint to flow out nicely. If you use the small needle and cap, you're starving the paint stream of air and the paint will not atomize properly to give you a nice finish.

On the other hand, of you use a large needle to spray thin finishes like laquer or water-borne polyurethane, the finish will come out as globs.

As I have only sprayed with gravity fed sprayers, I would assume the siphon fed sprayers have something similar to control paint/air flow, bigger cap etc.

Hope this helps.

[Brett Nelson]

Thanks for your reply, but I can't use a rattle can, because I need to match a particular paint color, and I can't get that color from a rattle can.
Since I've never used a paint sprayer with a compressor, can you explain what you mean by a larger tip? Are you saying that the tips of paint sprayers can be changed?
Louis


Given your statements, trying to spray this is going to be a bigger chore than you want it to be if you go the route you are trying to. Do yourself a favor. Go to your local auto paint supplier, they should have something like this.

http://www.amazon.com/Preval-Spray-Power-Unit-Container/dp/B001ENSKUY/ref=sr_1_2?ie=UTF8&s=hi&qid=1268792590&sr=8-2

Or you can just buy the one there on Amazon. Only costs $5 and the aerosol cans are replaceable for future projects for about $3 each.

It will spray your custom color latex no prob. If you'll only ever be spraying small jobs, then this is the way to go. BTW, most high quality latex is meant to be sprayed with a airless sprayer and will subsequently take on a lower sheen if sprayed with air or aerosol. Don't know if that matters to you.

[Lorne Steed]

Louis ; Hi - I've been a professional painter for 38 years and do a good deal of my work in the shop doing furniture finishing and refinishing. Your outfit is undersized as the requirements would usually read about 4 or 5 horsepower and probably about 8 to 10 SCFM to adequately atomize latex with conventional outfits. A dedicated HVLP puts out a lot more than that but at a very low psi( usually 10 psi) Why don't you just rent a proper system from Home Depot or your local rental yard if this is just going to be a one-off kind of a thing. Otherwise if you insist on using an underpowered compressor and spraying conventional then you will have to get a gun with the right needle and air cap set-up. You should be looking at about a .4 or .5 needle and tip set .If you try to use a 1.3 or 1.4 ( which most of the cheap dime store variety are, then you will immediately use up the air you have stored in your tank and all the compressor will do is stay on as long as you hold the gun open. In other words it will not be able to store enough "juice" to atomize the paint. If you decide to use latex in a conventional system then you will also need an needle and tip set that does not rust (read stainless steel). Home Depot or even most paint stores will rent you a dedicated HVLP system that will do the job you want to do properly.

Lorne Steed

[Curt Harms]

It's no Binks or Accuspray but it may be adequate for what you need to do and will work with your compressor:http://www.leevalley.com/wood/page.aspx?c=2&p=20048&cat=1,190,43034&ap=1. Spend a little time and material experimenting. Don't use more air pressure than necessary and you won't get too much overspray. Of course more air pressure=better atomization so it's a trade off. I used one with acrylic enamel and it gave a pretty good finish.