Most Effective Way to Spray Cabinet Doors
Right now we spray everything one at a time on a lazy susan and stack the doors on Hafele drying racks. We shoot two coats on the back then two coats on the front. Lots of handling going on, but the process keeps moving. I have a finisher spraying and a helper sanding/handing parts. I'm not sure, with our physical layout, that I'm going to come up with a better process.
I've seen shops that lay all their doors out in rows on sawhorses, then spray, sand, spray, turn, repeat. My room size would require me to spray my doors in two or more batches to get everything done. My finishing area is away from my shop, so there's the issue of what to do with the guys while the batch is drying. Is it even worth trying this?
However, as far as the spraying MO, here is how I do it. I use conversion varnish. Two coats is all you need if you are using a good AAA like the Kremlin or CAT. Spray back 1 coat, let cure, flip and spray face. Sand both sides. Spray back final coat, let cure. Flip and spray face. Done. Aside from UV-cured processes, kind of hard to beat that system. The only problem is if you have a heavy hand spraying, you might get overspray on the backside when spraying the final on the face. I only had problems with it if I was spraying at too flat of an angle on the edges (allowing it to flow under the door too easily) and spraying too heavy.
From the original questioner:
Thanks, but I'm not clear on what you're telling me. Are you spraying your doors one at a time and using the wooden racks for stacking, or do you have roll-around racks built that allow you to lay out/spray several doors flat and leave them there? I've seen the latter type of arrangement, but we don't have room in our spray area for all those carts.
My spraying procedure is essentially the same as yours, only I spray both coats on the back first and then flip. Your method allows you to handle the door just once for sanding. I have to handle it twice my way. We're using a Kremlin rig and spraying Magnamax. Those 50-door Hafele racks can't be beat, particularly when you get them on sale.
From contributor M:
I spray the doors one at a time. Now, if the spray booth I'm in is big enough and has a big enough filter wall, another guy can be laying them out for me to spray and putting them back up. Doing that, we might be able to have four doors at a time sitting out to be sprayed, and I (the sprayer) would have no downtime between doors. With the racks I was referring to, you can't spray them sitting on the rack - overspray would be a nightmare.
From contributor B:
Here's an idea I gleaned from Conestoga's catalog regarding finishing specs:
"colortone products are placed on drying racks after the coating application process. Small indentations or pin marks from drying racks will appear on the backs of... and are not considered defects."
I used this idea to make plywood beds with screw points sticking up. A door is placed gently face down, the back is sprayed first, not the edges, flipped over and sprayed the face and edges. This plywood bed and door is set on the drying rack. Both sides are drying at the same time, cutting finish time in half. An occasional down side is a very small dimple on the back side because of the pin point, but generally, the finish flows into the area and is very difficult to see. At the very least, do the priming and first topcoat with this system, then do the final coat one side at a time to ensure perfect finish.
From the original questioner:
Contributor B, are you spraying multiple parts laid out at one time, or one part at a time, then stacking? The table on my lazy susan is a bed-of-nails concept, but instead of using screws, we sharpened 3/8" hickory dowels in the pencil sharpener and drove them through the plywood from the back to keep the points sharp. (My wife's idea.) The dowels don't scratch the work pieces at all and clean up pretty easy with sandpaper if you get lacquer buildup on them.
From contributor Y:
Where are you guys getting these Hafele drying racks?
From contributor M:
As far as the lazy susan, are you referring to what you lay the individual parts on as you spray them? I've always used a cheap TV swivel sitting on a yard-sale barstool. I once used the bed of nails, but now I don't bother if I'm using an AAA, since overspray is dramatically reduced to the point that it does not affect the backside.
From contributor S:
I use the same method contributor B has described. I lay out as large a batch as possible which typically is 5-6 rows of 5-6 doors/drawer fronts each (total of 30). Here is my typical schedule (conversion varnish, pressure pot, minimum 25 ft. hoses from pot to gun).
1) Clean finishing room well. Sweep and/or vacuum floor beginning at back of room moving towards the booth (with the fan on). If vacuuming, make sure to use a HEPA so the fine particulates are not just coming out the backside. Blow off any drying racks that will be used. Then starting at the back of the room again, use compressed air to move the airborne dust towards the booth. (The importance of this cleaning will be evident when you reach the sanding operation.) (20 minutes)
2) Set up the rows (sawhorses), nail boards and doors onto nailboards, backside up. (10 minutes)
3) Starting from the back row, final blow off of dust from items to be sprayed. (Most all dust is first blown off before items enter the spray room!) Blow the dust off yourself well while standing in the booth. (8 minutes)
4) Starting at back row begin spraying the backs (only, not edges) starting first at item farthest from the pot and moving towards the pot (hose behind you). Move to next row, repeat until complete. (This will vary based on your equipment and personal speed. I spray very fast and robotic. You will be able to also once you get used to the system.) (5 minutes)
5) Flip the doors starting at first one sprayed. (3 minutes)
6) Repeat spraying edges first, then fronts. (8 minutes)
7) Tiptoe away, let doors flash.(5 - ? minutes) (Your flash time may be longer depending on your coating and conditions - you want it dry enough that it won't stick to the rack.) I also allow longer for a final coat.
8) Move doors to rack (first sprayed first) and remove rack to sanding station outside finishing room. (5 minutes)
If you have more doors, lay them out, blow them off, and repeat spraying. *You do not need to reclean the room.* (Always clean the room if you are switching projects from a pigmented coating to a clear coat project.)
Key here is to limit the amount of movement in the room during spraying and flash off. (Anyone tries to enter when I'm spraying will experience death by bunga bunga!)
Very little (if any) junk should show up on the finish using this method and sanding time is drastically reduced. If you have sanding helpers, sanding on the first batch can usually begin (outside the room) while the second batch is still being sprayed. So, in approximately 1.75 - 2 hours, 60 door fronts and backs are sprayed and 30 of them are almost done being sanded and are ready for a second coat. With the sanding helpers you can keep a finishing room in near constant production mode. With the reduced handling of this method, would this production time beat your current schedule? If not, then your current system isn't broke, so don't fix it.
From the original questioner:
Yes, the lazy susan is what I spray the parts on. Mine is a piece of 1 1/2" black pipe screwed into a pipe flange and that's screwed to a 24" x 24" piece of plywood. That's the base. The turntable is a piece of 3/4" black pipe screwed into a pipe flange with a bed of nails screwed to that. Just stick the smaller pipe into the larger pipe... Works great.
My spray room is 16'x18' with a 23'x25' drying area (these are actually two garages at my house, but it's dedicated finishing area). I figure I could get 24 doors sprayed in one batch in my room. I just need to try this once and see if it makes me any money. The way we're doing things now keeps the sprayer on the gun constantly, and I guess that's the issue.
Contributor Y, go to the Hafele website. The part number you're looking for is 007.91.141.
From contributor I:
No matter how many doors you lay out, you can only spray one at a time. (I believe Confucius said that.)
I have a 4 sided rack that holds 80 doors. It is on wheels and can be moved easily. I have worked at shops using the lay-out-everywhere-and-spray method, and was not impressed. Usually there were missed spots and overspray. And when the inevitable - this has to be done right now! - comes in the door, you're screwed.
Spraying one door at a time, you tend to focus more on technique for each door. The lighting is perfect for every door and the rack is right behind you, so as you spray you place the wet door at the top of the rack and get the one below it to do next. As an added benefit, less dust falls on things placed in a rack.
Usually by the time you have gone through all of the doors in the rack, the first ones you sprayed are ready for either scuffing or spraying on the other side.
I have seen people place their wet doors on the bottom of the rack and go up. This is a mistake, as you will knock dust onto the wet door below when you put in the door you just sprayed.
From contributor S:
Missed spots (holidays) and overspray are indicative of a shop that has employed sprayers rather than professional career finishers. The latter do not produce these results, as they don't struggle with technique, whether they are spraying one piece at a time or many. And while professional finishers always appreciate correct lighting, many can spray perfectly with little light at all.
Perhaps it is simply your personal enjoyment to spray one widget at a time, treating each as if it is a one-of-a-kind artifact. Maybe you just like the break in stride afforded by hanging up the gun and stretching a bit as you place a wet item onto a rack and reset another. Everyone does have to find what works for them.
Either way, I agree that racking from the top down is a no-brainer, and I have also seen others make the mistake of racking bottom up. But you have made my point about dust in a wet coat.
Whenever there is excess movement during a finishing operation, dust will be kicked up, knocked down, etc. And when you pick up a freshly wet item and move it through the airstream taking place during a fan on session, you are directly causing the particulates in the air to collide with the wet coat. Hence the reason to allow some flash time before moving the item or movement in the room.
As for the "inevitable, this has to be done right now... you're screwed" problem you have stated as additional reasoning, my reasoning on that is "a lack of planning on so and so's part does not constitute an emergency on mine." If they can't wait an hour for a switchover, they are screwed.
To the original questioner: Having the gun in action full time is not what will determine your increase in production and profits. You can have two helpers picking up, racking and feeding items to keep a gun in constant motion, but that still requires additional handling steps and man hours times "X" per man hour. Whereas batch finishing can be performed by one person.
Additional throughput can be achieved with other warm bodies (less skilled lower wage) if you have them, performing the sanding operations. You have to do a calculation of all these factors to determine the payoff and if this would work for you.
Another benefit of batch finishing is that it also eliminates the tracking requirements as to which piece is ready for sanding first. The whole rack was sprayed within a few minutes of each other, rather than a 40 minute or whatever spread, and are all ready for the next operation at the same time. I know most people should be able to track a first on, first off rack method, but if you ever have to relay directions to prep personnel who don't speak or understand English, this cuts down on any confusion.
Your two-room garage setup sounds fine. A lot depends on what your coating properties are. If your coating has a much longer flash or dry to sand time, then you have parameters which could make batch finishing reach a point of diminishing returns. You have to find out for yourself.
From the original questioner:
I think we're doing okay given our physical layout, but I'm always looking for a better mousetrap. We're spraying Magnamax, so our flash time isn't too bad considering our batch sizes. I have a dedicated spray guy and a $7 per hour helper we use on an as-needed basis. He's a teenager from our church and believe it or not, he does a fantastic job, particularly when my wife feeds him. I'm still going to try the batch spray method and give it a fair evaluation.
From contributor L:
I personally do not like to move anything before it is set up, so I guess I batch finish. I have made several spray tables. Picture picnic table type seating - they roll out on extensions. They are set up with the sharpened wooden dowels (thought I was the only one!). I set up all the doors/shelves, and then shoot the stuff on the table top, then pull out the "drawer" holding the second set of doors, and shoot them, then push the set under the table. It makes for better use of the space. I don't have the overspray problems that many of you seem to. I don't know why. I just do not like having to handle wet parts. Even the "lazy susan" concept is lost on me... Wasting the time fiddling with spinning a door around just seems inefficient.
From contributor D:
I favor the rack system. I can very comfortably spray a rack of average size cab doors, taking them off the rack and returning with wet finish individually without any helper and without hanging up the gun between doors.
Another consideration is a large crossdraft booth sitting at the end of the finishing area. This is very common and is designed for optimum air draw at the very front of the booth. As you extend outward from the front of the booth, the draw is more turbulent or at least inconsistent. Obviously it is not a problem for some, but it wouldn't work for me, as my room the booth sits in is too large with 14' ceiling height, so the air flow 20' away from the booth is not adequate to carry overspray.
Another issue is NFPA code. To get my occupancy with city building inspectors, I had to sign a statement saying I would not spray objects out in the room area away from my spray booth. All spraying is to be done at the front face of the booth or inside that limit. If you comply to this, then all lighting and electrical outside 3' or 5' from the booth can be standard. If you spray in the area well outside your booth, then all your lighting and electrical has to be up to tighter code for inside a spray booth, which is quite a bit more expensive and is necessary for good reason.
The most obvious thing that stands out to me in the original post is that his room is small and would require two or more batch runs if he were to go this way. Seems to me that is a deal killer, but sure, give it a try and find out.
From contributor S:
Batch finishing has been very effective for me when schedules are extremely tight and deadlines and profits are dependent on just how fast I can produce a top notch finish. Much of my work over the years has been private labeling for others in the business (cabinetmakers and refinishing shops). I have turnkey access to many shops, so I can - often after hours - produce a project for them. I bring my own spray rig/materials and boot into their compressor.
They pick up a fairly healthy percentage of the finishing profit for doing the marketing and selling the job. I make an almost sinful amount without having to cover the overhead costs. It is a deserved sinful amount, seeing as I will pull a 20 hour shift (maybe with a catnap on the office sofa), and get up at 4 AM to spray the final coat before their staff shows up for their daily shift.
They get a project done that they may not have the expertise or schedule to produce with their staff, pick up pure profit (but for electricity/heat) and get all the credit for the end product. Sometimes it gets them out of a real bind they are in. They know they can count on me to get it done right (I usually produce the samples in the first place).The faster I get in and out, the more money I make.
I also can rent the spray room time for my direct sale jobs I land. I do a lot of on site kitchen and bath finish jobs (waterbased), and like to pull the doors and drawers out to spray those. It is win/win.
There is no end to the variables in finishing. Being able to quickly identify and adapt to which is the best method for any given project is key to enjoying the process and the profits.
From contributor G:
I use sawhorses with 2- 2" wide 8' long pieces of wood between them. I put 5 doors at a time, spray 1 coat pre-cat lacquer on front, return them to the mobile drying rack, get the next 5, etc. I spray the doors large to small. I turn my sticks over when I start on the second side of the rack. By the time I have the second side of the rack sprayed, the first side is dry and I spray 1 coat on the back, same process as before. I buff the first side of the rack fronts and backs. When I get them buffed, the second side is dry and ready to be buffed. I then reverse the spraying order, backs then fronts. I hold the gun at a 45 degree angle while I'm spraying the edges on the final coat on the fronts so I don't have overspray on the backs of the doors. I do the same thing with drawer fronts.
I spray, move and buff by myself and this is the fastest, most efficient system for me, with excellent results. Using this method, a batch of 50 doors/20 drawer fronts takes me about 3 1/2 - 4 hours from start to finish. I've tried other methods and was not satisfied with any of them. What works for me may not work for somebody else. Trial and error!
From contributor M:
On a somewhat different angle, people are often trying to rearrange their finish schedule to reduce time. In all my 4 years (no, that's not missing a 0) of being a finisher, the most effective way I've seen to reduce labor cost is to get better at it every time - learn your stuff. Where I am now we use a lot more standard poly and spar, which I am not accustomed to, and it's an interesting learning experience.
That being a given, the second easiest way to reduce finish time is to use better equipment and materials.
1) Using a good air-assisted airless (or perhaps a pressure pot with HVLP gun). Very hard to beat the sheer output and high quality of finish these guns produce, not to mention greatly reduced overspray.
2) Spray the fastest-curing stuff, which for us is normally conversion varnish, but at times we'll use 2K poly. Most brands of either of these will cure quicker then pre-cats and NC lacquers.
3) Eliminate color-squabbling with customers by being clear to them that color will vary a bit because we are working with wood. Stain color does not equal paint color. Have a "wipe-on, wipe off" policy, none of this "wipe it on, wait for X minutes, wipe it off," because it's really aggravating to be timing how long the stain's been on all those doors.
From contributor V:
I was interested in the many different ways that smaller companies are finishing cabinet parts. I would really recommend an air assist gun, as they only use 2 to 3 cfm of compressed air, and provide an excellent lay down of the coatings.
It seemed that most were looking for 50 to 60 parts at a time. Why not invest in a small overhead conveyor? Hang the parts on the conveyor after white wood sanding, and start the conveyor. Apply the stain on both front and back, and the edges at the same time. If the conveyor were 20 by 20, that is 80 feet of conveyor. If the parts are on 2 foot centers, you can stain 40 parts. When the first stained part returns to the booth, stop the conveyor, change to your sealer, and then seal coat all 6 surfaces at one time. This is the front, back and four edges. As the conveyor continues to run, the parts will be finished on all 6 surfaces at the same time. This will provide the best edge coverage.
If you have a helper, he can sand the parts before they get back to the spraybooth. The conveyor will then bring the parts back to the spray booth ready for the topcoat. The denibbing of the sealer coat needs to be blown off, but the parts are ready for topcoating. The gun is then filled with topcoat, or left if it is a sealer/topcoat dual material. The conveyor will continue to bring the parts into and out of the booth, which will allow one sprayer to apply the finish to the entire batch of parts.
The sealer top coat should also be a water reducible coating. This will allow for a green coating, which will allow you to provide a kitchen and meet the CARB requirements.
The conveyor system will allow you to finish the parts without touching them except for the denibbing after the seal coat. If the conveyor runs at 3 fpm, this is almost 30 minutes of dry time between coats. This means that one person would finish 40 parts, stain, sealer and topcoat in about 1 1/2 hours. If you were alone, it would be 2 hours, as he would denib the parts on line after the sealer coat. 40 parts with three coats and sanding in 2 hours is productive.
Monorail conveyors are inexpensive, and allow the operator the keep spraying. As far as the thickness, I like 1/2 mil for stain, or as required to get the correct coverage, and then 3 1/2 mils of sealer and topcoat. Most of the sealer topcoats have a volume solids of 30%, so this will provide a 2 mil dry film build on all surfaces, which result is a great finish package.
From contributor W:
We have used both methods over the years and found the lazy suzan/rack method to be faster. We use two lazy suzans right in front of the booth with the racks just behind the finisher. The finisher sprays while the helper moves the doors. The lazy suzan we built is similar to a potter's wheel with a pedestal on top. You can kick it to turn the door so you don't have to touch anything with your hands. I did some time studies on this some time back and it boiled down to extra time for laying out the doors and picking up vs standing right at the rack and spraying. When we use the LS/rack method, I have also found that there is never an "I was waiting for doors to dry" excuse from the finisher.
From the original questioner:
Contributor W, I actually got the lazy susan idea from you when I visited your shop. Since I initially made this post I've tried laying out doors in rows and it's not as fast (for us) as using the l/s and racks. The way my spray room is set up, I could only get about 18 doors on the stands at one time. We were waiting too long for stuff to dry. The way I'm doing it now, we can move from doors to panels to frames to moulding without any hassles. I think I'll leave well enough alone.
From contributor W:
Why not use 2 lazy suzan setups and get help with moving the parts? That way you are never putting down the gun. It is a lot faster that way.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor B:
Comment from contributor A:
I spray batches of 40 plus doors with an airless. I hang my doors with little hooks in the hinge screw holes on cable or heavy gauge picture wire. I hang them in multiple rows with each spread as far apart as reasonable to avoid overspray. If finishing on site (new construction) before painters you can screw eye-bolts into studs in the walls and caulk them after you're done.
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