Sprayer for Priming

To prime or not to prime...that is NOT the question.

I have been using rattle can version of SEM primer thus far, however as I primed the ribs for the wing, I noticed I started going through cans quite quickly.

There is a lot of convinces and ease of use in the rattle cans, but I'm starting to consider a sprayer. I have a wagner paint sprayer which I know will now work, so considering a HVLP. I have heard a few folks mention that harbor freight has an inexpensive one.

What is everyones thought on moving up to a sprayer, vs staying with a rattle can moving forward with the wings and fuselage, and any advice on a HVLP sprayer?

Thanks


Dave
RV-7 in process

In general, you'll come out cheaper buying paint/primer in bulk than using rattle cans, and you'll (likely) be using higher quality paints too.

The "purple gun" from Harbor Freight is my go-to cheap gun. Get the one with the 20 ounce cup and the regulator included. About $30 when it isn't on sale, far less when it is. I've sprayed everything from epoxy primer to high build primer to single stage to base/clear with it and it is a really good, inexpensive solution.

https://www.harborfreight.com/20-oz-hvlp-gravity-feed-air-spray-gun-with-regulator-62381.html

The primer product you intend to use should have a paint gun orifice recommendation in their instructions. Just make sure your gun has a tip size iin that range.

HVLP

Kyle Boatright said:

In general, you'll come out cheaper buying paint/primer in bulk than using rattle cans, and you'll (likely) be using higher quality paints too.

The "purple gun" from Harbor Freight is my go-to cheap gun. Get the one with the 20 ounce cup and the regulator included. About $30 when it isn't on sale, far less when it is. I've sprayed everything from epoxy primer to high build primer to single stage to base/clear with it and it is a really good, inexpensive solution.

https://www.harborfreight.com/20-oz-hvlp-gravity-feed-air-spray-gun-with-regulator-62381.html

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Agreed. Use a 20% coupon and save even more. I would recommend a disposable cup solution like 3MPPS. Cuts down on cleaning. Gab a couple red disposable water/oil filters too. I prefer the RTI mini regulator.

Kyle Boatright said:

In general, you'll come out cheaper buying paint/primer in bulk than using rattle cans, and you'll (likely) be using higher quality paints too.

The "purple gun" from Harbor Freight is my go-to cheap gun. Get the one with the 20 ounce cup and the regulator included. About $30 when it isn't on sale, far less when it is. I've sprayed everything from epoxy primer to high build primer to single stage to base/clear with it and it is a really good, inexpensive solution.

https://www.harborfreight.com/20-oz-hvlp-gravity-feed-air-spray-gun-with-regulator-62381.html

Click to expand...

Yep,,,good gun for this purpose. They go on sale sometimes for under $10,,,,ad the 20% coupon and your at $8. I always have a couple NIB on my shelf in case I am too lazy/tired to clean it,,,,I just throw it away and grab a new one off the shelf next time I am in need, and buy another one when on sale again. They have a new line of "professional" spray guns in their line-up that run around $100 and wonder if anyone has tried it for a finish coat. I have a DevilBiss Tekna using DeKups for finish coat but would not hesitate to try one if I didn't.

The harbor freight gun seems to be sufficient for primer. I like the one with the regulator but the others are good as backups. These are cheap guns so they do break or the cups crack and leak. I've gone through a few during my build but they are cheap enough to not worry about it. Look for sales or coupons the price can be discounted quite a bit.

Thank you all, the comments were very helpful.

Are we talking about priming the whole exterior at once or priming the individual fabricated pieces? I can't see using the bowl of a full size gun for small parts without wasting a lot of mixed primer.

I used an air brush for 90% of the primed parts of my standard build. The bigger surfaces like tips and cowl were done with a cheap (HF ish) touch up gun, For those that don't know what a touch up gun is, it is simply a full function gun with a small supply bowl. The trigger is different too but that is not important. The small bowl is.

If I chose to paint the exterior, then I would get a full sized gun but I would still use the air brush for fabricated parts.

With Akzo, I use a primer pistol exclusively for all my interior and a few exterior parts, tho for a full exterior in prep for a paint job, Id go with a proper HLPV gun. I have the HF purple gun but have yet to actually use it.

rzbill said:

Are we talking about priming the whole exterior at once or priming the individual fabricated pieces? I can't see using the bowl of a full size gun for small parts without wasting a lot of mixed primer.
.

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There is little or no difference in the amount of paint wasted or cleaning time between a big gun and a little gun. In both cases, you mix slightly more paint than you think you'll need (nothing worse than running out of primer 97% through the job), spray the items, and clean up.

Man, I can't believe you guys would have the nerve to recommend using a tool priced at less than .1 AMU for a space-qualified a/c like the RV, *especially* on *this* forum.

Charlie
(Kolb Twinstar restored, and painted completely with a H.F. p/n 67181)

(obligatory ;-), added for clarity )

Waste

Kyle Boatright said:

There is little or no difference in the amount of paint wasted or cleaning time between a big gun and a little gun. In both cases, you mix slightly more paint than you think you'll need (nothing worse than running out of primer 97% through the job), spray the items, and clean up.

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Easy fix. Buy a disposable cup system with small cups. Calculate the amount of paint used on a few jobs then use the formula plus 10% moving forward. I waste very little and if there is any left, I collapse the cup and cap it. Often a little part needs primer or some holes need a touch up.

rzbill said:

Are we talking about priming the whole exterior at once or priming the individual fabricated pieces? I can't see using the bowl of a full size gun for small parts without wasting a lot of mixed primer.

Click to expand...

You can dial back a full-sized sprayer to have about a 2-3" spray pattern and not waste too much. Top-cup sprayers will use about 99% of the material put in them. The rest is stuck to the cup. You won't get the transfer efficiency that an airbrush gives but it's also a magnitude or two faster.

I've been prepping entire sub-assemblies and spraying them. Use a 4-6" spray pattern on skins and 2-3" on ribs and spars, etc. Total transfer efficiency is probably around 60% due to the ribs. It takes 10-15 minutes to spray everything and most of that is spent moving parts around.


As for guns, I've used both styles of HF guns, Sharpe, DeVilbiss, Binks, Eastwood, Craftsman, and a few others. They all spray primer just fine. The $30 HF is a definite upgrade from the $10 one.

I would consider the $10 HF gun disposable. Every one of them has developed an issue over time where they'd have an inconsistent transfer or leaked or whatever. They get binned once that starts. i've never been able to figure out a fix. The better guns never have the same issue and I clean them all the same.

There are a couple of things you can do to set yourself up for success: 1) throw away the little in-cup filter and use proper (~190 micron) strainers. 50 of them will run you about $8-10. Pour the mixed primer through it and into the gun 2) get an on-gun regulator and use it to adjust pressure with the gun running. 3) learn to setup the gun to get a proper fan and flow. You want to be able to pull the trigger all the way to the stop and spray (don't try to feather the paint by hand). Then you just need to get the 40-50% overlap to get success. 4) be sure to keep the vent in the cup clear and clean. if that clogs your paint won't flow. 5) painting is 95% prep, 4% cleanup, and 1% actually spraying stuff.

Also, be sure your compressor is big enough. HVLP guns like air and a lot of it. Most 110v compressors are going to struggle to supply enough air to spray continuously.

DeKups or 3M PPS cups are amazing as well. I bought the PPS 2.0 system this year and can't believe I didn't buy it earlier. It's nearly a wash vs buying regular mixing cups and strainers. Probably < $1 difference per spraying session.

For clarification I am talking about priming the parts during construction. Right now I'm thinking professional job for the exterior when its assembled. I figure it should atlas look nice even if it flys crooked.

So far I have had good success with the rattle can, and I think I may have found a place online that's not too bad if I buy the cans by the case, the other issue I have to look into is my compressor size. It works fine so far with my rivet gun and air drill, all though it has just enough capacity for the air drill. It would be a good excuse to 'upgrade' my compressor, but just received a 'ball park' estimate for one of the 'keep the wife happy' home projects, and....well maybe not just yet on the compressor

HVLP

Dave S said:

For clarification I am talking about priming the parts during construction. Right now I'm thinking professional job for the exterior when its assembled. I figure it should atlas look nice even if it flys crooked.

So far I have had good success with the rattle can, and I think I may have found a place online that's not too bad if I buy the cans by the case, the other issue I have to look into is my compressor size. It works fine so far with my rivet gun and air drill, all though it has just enough capacity for the air drill. It would be a good excuse to 'upgrade' my compressor, but just received a 'ball park' estimate for one of the 'keep the wife happy' home projects, and....well maybe not just yet on the compressor

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I primed everything inside with a DeVilbiss FLG and a 30 year old Craftsman 5HP, 20G, 220v compressor. Yea. I had to stop and flip parts and let the old girl catch up but it can be done.
She's pretty tired but still has some life left. I drain the tank and check oil often. Keep your eye on Craigslist. I've seen some killer deals.

If you're planning on staying in the region, then you don't need to prime. Closer to the coast, certainly. Just something to consider.

I've got a 1955 Cessna that was never primed. It spent most of its life in the middle of the country, and has very little corrosion. What corrosion it does have was from six months tied down outside of Philadelphia. It spend several years in Oxnard, CA, a scant few miles from the beach, and was in a hangar. That did not add to the corrosion. It was a good hangar.

Dave

Kyle Boatright said:

There is little or no difference in the amount of paint wasted or cleaning time between a big gun and a little gun. In both cases, you mix slightly more paint than you think you'll need (nothing worse than running out of primer 97% through the job), spray the items, and clean up.

Click to expand...

I have a hard time with the idea of mixing 1oz of 2 part primer in a quart paint gun and then hoping that any will come out the nozzle because it won't reach the siphon. With the airbrush, that fills the jar and will do the half dozen parts fabricated that evening.

rzbill said:

I have a hard time with the idea of mixing 1oz of 2 part primer in a quart paint gun and then hoping that any will come out the nozzle because it won't reach the siphon. With the airbrush, that fills the jar and will do the half dozen parts fabricated that evening.

Click to expand...

The HF gun we're talking about gravity feeds from a top mounted cup - it doesn't have a siphon. Every drop of paint other than the film left in the cup can be used...

rzbill said:

I have a hard time with the idea of mixing 1oz of 2 part primer in a quart paint gun and then hoping that any will come out the nozzle because it won't reach the siphon. With the airbrush, that fills the jar and will do the half dozen parts fabricated that evening.

Click to expand...

Hi Bill,

I know almost nothing about airbrushes. My initial reaction is concern that an airbrush would have a tough time spraying primer because it?s too thick for the orfice. Is this a problem?

My logic may be flawed because most of the primer I?ve sprayed is the thick and juicy high build primer intended for fiberglass pieces. Is this just not an issue for metal primers like Azko?

What?s the widest fan setting on the airbrush setup you?re using?

Can you post the make and model for your setup? This isn?t something I?ve considered, but it sounds like it has potential!

Thanks in advance!

Kyle Boatright said:

The HF gun we're talking about gravity feeds from a top mounted cup - it doesn't have a siphon. Every drop of paint other than the film left in the cup can be used...

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Thanks Kyle, I have not used that model. Sounds like it would work fine. I had missed looking at your link posted earlier.

Rwoodard,
I used Dupont Variprime self etching primer which is thin and can be reduced if needed. It dries really fast which was nice.

David Paule said:

If you're planning on staying in the region, then you don't need to prime. Closer to the coast, certainly. Just something to consider.

I've got a 1955 Cessna that was never primed. It spent most of its life in the middle of the country, and has very little corrosion. What corrosion it does have was from six months tied down outside of Philadelphia. It spend several years in Oxnard, CA, a scant few miles from the beach, and was in a hangar. That did not add to the corrosion. It was a good hangar.

Dave

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Dave, Thats the thought process I have, but even still I thought you need to prime all the bare metal parts, like the ribs and stiffeners. I generally figure if you don't pull off the blue plastic and it isn't already coated (like the control surface brackets) then you do need to prime.