It’s not deep enough, front to back, is the most likely suspect.

I think there’s always going to be some grease that gets away from the hood. You can’t contain every droplet of effluent, even if you have the best hood in the universe. That’s why I recommend metal hoods that can be easily wiped, and don’t like wood or plaster hoods.

It’s a kitchen, not a hospital operating room. People get obsessed with the idea of pristine rather than accept that a kitchen is where you prepare and cook food. Just like a cooktop or oven will not stay the way it looked in the store, or a stainless sink won’t remain scratchless (people post about these with surprise). A kitchen is gonna have surfaces that will need to be wiped clean, including the hood even if it’s deep enough and powerful enough. I blame TV shows, Pinterest and other social media for making people crazy over keeping a kitchen pristine.

No, it's not TV shows, Pinterest or other social media -- it's just me liking things clean LOL!

The hood is 24" deep, which is the depth of the stove. I was not able to fit a 36" wide hood over the 30" stove, space between cabinets was just a bit too shy to get it to fit. Believe me - I tried. I tried because DH is a fryin' fool. Reference my other post about the deep fryer in the garage. The sizzling pan frying is done in the kitchen, can't really banish that to the garage. (well, I could if I had the funds to build him his own personal kitchen out there, or an outdoor set-up off the back patio...)

First, as noted above, cooking plumes have an angle distribution and for modest air flows around the pan, some effluent can escape capture and containment, particularly when there is turbulence from drafts and motion of people.

In this case we can evaluate the system that you only partly described. The max rated flow rate for this hood, taken from a Lowes ad, is 400 CFM, which for likely pressure losses means a real flow rate around 250 - 300 CFM. A 24 x 30 inch hood should have around 450 CFM actual (650 - 700 CFM rated). So hot oil cooking plumes that can reach 1.2 m/s peak velocity may partially reflect out of the hood and drift into the room. Electrostatic effects may preferentially cause the grease particles to attach to the hood. I doubt, however, that the hood is the only place where grease attaches, just the easiest to see before the grease rancidifies and becomes relatively hard and less obvious than on a smooth metal surface. Odor may be minimized by general air removal from the kitchen after periods of high effluent generation, typically brief such as meat searing.

Are you depending on house leakage for make-up air, or do you have a deliberate MUA system.

Edit: Does the "fryin' fool" remember to turn the blower on high before starting?

No make-up air system. He sometimes remembers to turn it on first and often doesn't run it on high when he's cooking. I've tried to train him....sigh...I think he just doesn't pay attention, he's so focused on the food.

I have a 54" Wide custom pro hood over a 48" high BTU range. Hood is 24" deep and has a 1200CFM blower. I still get a light film grease on my hood. Not a lot...but it probably needs to cleaned several times a year? Maybe more often, but I'm not a overly obsessive cleaner. I just cleaned it this week....I don't remember the last time it was wiped down....still, it only had a very light coating. The only way I could tell was the texture of it when I wiped it down.

heres a pic with my DH.

Plain & Fancy Kitchen - Dayton Ohio · More Info

^^ I'm envious -- what a set-up! (your DH looks pretty good too!)

AND he cooks for me every day! LOL

Then he's definitely a keeper!!

Part of your problem is the hood size -- if you (or your "fryin' fool" DH) do a lot of frying, then the hood really needs to be 6" wider than the cooking surface. Failing that, then you should probably have a more powerful hood -- but you will need makeup air for that.

For the greatest benefit, the hood should be turned on a few minutes before cooking begins. Focusing on the food isn't a real excuse -- there's no reason why he cannot do it while he's getting ingredients together or prepping the food he plans to cook/fry. After he does it a few times, it will become part of his routine.

What might help? Tell him he has to wipe down the hood every time he cooks!

My island hood is 6" wider than the cooking surface. Like others, I clean the outside of the hood about three times a year...and it's not a lot of grease....just a little. Z Line is a pretty nice hood, I own one, a 720cfm. I love putting the upper air grates in the dishwasher.

Only need to clean three times a year? I have to clean mine monthly. It's not a horrid build-up, but I can see it and the dust attaches to it.

Well, bless him! He cooks! Those of us with husbands who love to cook learn to live with less than perfect kitchens. Mine presented a fantastic, complicated dinner the other night, then looked sheepishly around the counters strewn with nearly every pan, dish, utensil, cookbook, dish cloth we own. I didn’t care. Dinner was great and he had a wonderful time cooking. Of course, my go to meal is meatloaf and baked potatoes-one dish!

It's nothing that the stainless cleaner wipe doesn't quickly take care of, maybe I'm making it sounds worse than it is. I just cleaned it the other day, I'll try to remember to snap a pick next time it needs cleaning.