No paint on the insides ... why did the custom cabinets come unfinished?

@BlueberryBundtcake - 6a/5b MA - That's how the carpenter built and installed them. The painter quoted us $3,000 to paint the cabinets so we decided to paint them ourselves.

I assumed it was pine that was used. It's probably oak now that I think about it.

@Jennifer Michalec The drawer fronts and doors appear to be poplar, that's not a bad thing, I just wanted to point that out.

The best I can tell from the pictures, the boxes were made from cabinet grade plywood that was unfinished on both sides. There is cabinet grade plywood available that has a UV cured finished on one or both sides. That's what is commonly used so the cabinet inside already has a finish.

It sounds like your insides are unfinished plywood. Is that true for the drawer boxes as well?

Don't paint the insides. If it's raw, unfinished wood, I would suggest you finish the insides with an oil based polyurethane. I recommend oil based because rather than brushing, you can wipe it on. They sell wiping polyurethane but it's easier and cheaper to just make your own. By wiping on the polyurethane you can get a finish that looks just like it was sprayed on. It's also faster and easier than applying by brush. Oil based polyurethane will amber over time. But it's inside the cabinet and many ready made cabinets have wood look vinyl covering on their insides as well. You can learn more about wiping poly here:

https://thewoodwhisperer.com/videos/wiping-varnish-shootout/

Here's a brief description of wiping on poly from the Marc the Wood Whisperer:

"The Wiping Method

Now there is yet another way to apply polyurethane that I feel is the easiest, beginner-friendly method. And frankly, it’s the method I still use. It involves abandoning brushes all together. Here’s what you do. Thin the varnish 50% with mineral spirits, paint thinner, or naptha. Then get yourself a clean cotton rag (old t-shirt material works great), and fold it into a nice square applicator pad. I like it to be palm-sized. Wet the applicator with your thinner and then dip it into your diluted finish. Wipe on smooth thin coats, overlapping the previous stroke with each pass by about half. This method will result in a super smooth finish with no bubbles and no brush strokes. But remember, you will need to apply twice as many coats to get to your desired film thickness. Because you are actually applying less material to the surface, the dry time is significantly decreased as well. So in some climates (hot and dry), you’ll be able to apply as many as three coats per day. Just remember that when you use a wipe-on urethane, you aren’t trying to flooding on a real thick layer. You are just coating the surface evenly with a thin wet film."

If you go the water based poly route, it has to be brushed. There is no water based wiping poly. It also drys extremely fast and won't get nearly as nice a finish appearance wise (i.e., brush strokes unless sprayed). Water based poly will not amber over time. If you had an HVLP spray rig, I'd say water based poly but I'm guessing you don't.

@missenigma - Thank you for the EXCELLENT information.

Seems a bit penny wise and pound foolish to go to the expense of having custom cabinetry made and not have the cabinetmaker do the finish work. Most of them have spray booths or rooms to apply the paint for a much nicer, even finish BEFORE they are installed.

But that ship has sailed, so I would highly recommend you hire a professional painter. And no, don't paint the insides unless you have glass doors on any of the cabinets.

@JudyG Designs - We are painting the cabinets with a Graco Magnum ProX19 airless paint sprayer.

I can't overstate enough the need to have a professional do the painting. I know $3K is a lot of money, so please get other estimates.

In the meantime, try paining one door yourself. Pick one that is the most inconspicuous, perhaps the lower cabinet door that faces inward on the island. If after painting one door, you love the look, then dive in and paint the frame. Reassess the results and decide if you want to do it yourself or hire a pro.

I have painted cabinets and I am a very experienced DIYer, maybe you are too. Even with all my painting experience, my results were middling at best. It really didn't matter because my cabinets were 40 years old and I needed to get only a few more years out of them until I did a total redo of my kitchen. But you have beautiful, new cabinets that you'll want to look at for 40 more years. If you can see brush strokes and paint drips, you will wish you had spent the money for a pro.

Worst case, leave them unpainted until you can save up for a pro. Get other estimates.

@Jennifer Michalec

"We are painting the cabinets with a Graco Magnum ProX19 airless paint sprayer."

You go GIRL!!

i have painted cabinets for more than one kitchen and they turned out fine.
It's painting, not rocket surgery.
https://www.familyhandyman.com/list/surprising-tips-for-painting-kitchen-cabinets/

Also oil-based polyurethane can leave a yellow tone, takes longer to dry, and can be an environmental pain to clean up. Look into General Finishes' water-based products:
https://generalfinishes.com/wood-finishes-retail/water-based-topcoats-and-sanding-sealer

This is just me, not a pro......I think it would be fun to have a color inside your cabinets, to coordinate with your kitchen colors.

The issue with paint inside the cabinets is that if the dishes are almost but not quite dry when put away, paint doesn't like water, and it has a tendency to get chipped or scuffed because most dishes aren't perfectly smooth on the bottom and come in and out frequently. It won't hold up well enough to make it worth doing.

If you're definitely doing this yourself, make sure to use a paint specifically designed for kitchen cabinets; it's higher use than most areas, has a higher moisture than most rooms (everything but bathroom), and requires more cleaning due to splatter, grease, and/or smoke. Also, unless you've dont this before, practice on something else to get a feel for your paint and equipment, and start with something inconspicuous, like tozmo suggested.

The professional might be pricier, but it depends on how you value your time and potential frustration. When we had our windows replaced, we debated whether we wanted to stain our own trim or get the painter to do it. We decided it was worth it to pay the painter, as it would be completed more quickly than if we did them one by one, and it meant we didn't have to match any stains, deal with the window in the middle of nowhere (needs a ladder or scaffold to get to it), or scrunch into spaces where vanities or the floor or such made it tight work. It was worth it for us to pay the money, as it would have cost us a lot of time (and cursing at that high window). Weigh your options carefully, sometimes you can buy happiness. LOL.

Just to provide more background info - This is an apartment built into half of our 30' x 50' metal barn on our 10 acres. We plan to live in it for no more than a year while we build our main house on the same land. So, we are saving money by doing what we can by ourselves (insulation, painting, flooring, trim/molding) and paying for everything else out of pocket.