If your acne cleared up years ago but the scars didn't, you're not alone. It's one of the most common frustrations we hear about, and one of the most confusing, because the same treatment seems to work wonders for one person and disappoint the next.

Here's the part that rarely gets explained: not all pitted acne scars are the same. Two marks that look identical in the mirror can sit at completely different depths, with different wall shapes and different tethering underneath. And that's exactly why a device like Secret RF helps some scars more than others.

In this article, we'll break down the three main shapes of pitted acne scars, explain why microneedling radiofrequency responds differently to each, and walk you through a simple mirror test so you can gauge your own. Read on.

Why Aren't All Acne Scars the Same?

Because they form at different depths and pull on different layers of skin. When the inflammation from a breakout clears, the tissue underneath sometimes rebuilds unevenly, leaving a sunken mark called an atrophic scar* — the surface dips instead of rising.

Atrophic scar*: a scar where the skin surface sits lower than the area around it, because collagen didn't fully rebuild. It's the opposite of a raised (hypertrophic) scar.

Dermatologists usually sort atrophic acne scars into three shapes. According to a review that classifies atrophic acne scars by shape, narrow icepick scars — under 2 mm wide and plunging in a deep V — make up roughly 60 to 70 percent of cases. Boxcar scars, 1.5 to 4 mm wide with sharp vertical walls, account for 20 to 30 percent. Rolling scars, up to 5 mm wide with soft, sloping edges, make up the remaining 15 to 25 percent.

Each shape has its problem on a different level. Icepick scars send a narrow tunnel deep into the dermis*, sometimes all the way to the fat beneath. Boxcar scars stand on steep walls, so once they pass about 0.5 mm deep, smoothing the surface alone leaves those walls behind. Rolling scars aren't really a surface problem at all — the floor is tethered down by fibrous bands, and until those bands release, the dip keeps coming back.

Dermis*: the thick layer of skin under the surface, packed with collagen and elastic fibers. It's where a scar's depth and recovery are largely decided.

Most faces carry a mix of all three, which is why "what treatment is best for acne scars?" rarely has a one-size-fits-all answer. The more useful question is which shape makes up most of yours.

How Does Secret RF Respond to Each Scar Shape?

It depends on whether the needle can actually reach the scar. Secret RF is a microneedling radiofrequency (RF) device: fine needles drop to a set depth and release heat only at their tips, so the surface stays relatively untouched while the dermis gets a signal to lay down fresh collagen. It's FDA-cleared, and, like most energy devices used on scars, it works by remodeling tissue over time rather than cutting anything out.

Microneedling RF*: a technique that inserts tiny needles into the skin and delivers RF heat from the needle tips. The heat concentrates at a chosen depth instead of on the surface.

In a clinical study of microneedling RF for acne scars, 31 people with grade 3 to 4 scarring had four sessions spaced six weeks apart, and about 80.64 percent improved by two grades or more. In the same study, rolling and boxcar scars responded better than icepick scars. That's a specific setup, though, so it doesn't mean everyone sees the same degree of change. Individual results vary.

Why the gap between shapes? It comes down to overlap: how much the zone the needles reach lines up with where the scar actually sits. Wide, shallow rolling scars and low-walled boxcars have their floor inside the dermal range the needles treat. Icepick scars don't — the tunnel is so narrow and deep that even as the surrounding dermis thickens, the tiny opening itself tends to stay put.

Here's how the shapes tend to sort out:

Which Acne Scar Shape Do You Have?

You can get a rough read in the mirror before you ever book a consultation. Gently stretch the skin sideways with two fingers and watch what the mark does. If it visibly flattens out, the floor is tethered, which points toward a rolling scar. If the edges stay sharp and square even when stretched, it leans boxcar. And if it looks like a tiny pinpoint that makeup never quite covers, it's most likely icepick.

This isn't a diagnosis, just a way to walk in with better questions. A dermatology reference from DermNet sorts scars the same way and pairs each with a different tool: tethered scars need those fibrous bands released so the skin can lift back up, while narrow deep scars are better handled one opening at a time. The same source notes that fixing color, texture, and depth together usually takes more than a single method.

Secret RF on its own tends to satisfy people when:

• Shallow boxcar and rolling scars dominate: the scar floor sits inside the dermal range the needles reach.

• Texture bothers you more than depth: smoothing the surface and enlarged pores is something this approach does well.

• You can't take long downtime: because it spares most of the surface, everyday recovery tends to be quick.

It's worth looking at other methods alongside it when:

• Icepick scars are everywhere: narrow openings respond better to a one-at-a-time approach.

• Deep boxcars won't stretch flat: those square walls can linger and stretch out your session count.

• New breakouts keep coming: calming active acne comes first, before any scar work.

How Many Sessions Does It Take?

More than one, and that's the honest answer. Scars fill in gradually rather than all at once, so most plans run several sessions about four to six weeks apart, then watch the change for up to three months after the last one. Collagen takes time to reorganize, which is why skin often looks better a few weeks out than it does on the day itself.

If icepick scars make up a large share of yours, adding sessions usually isn't the answer. That's the point to rethink the approach itself rather than just booking more. Your provider can help you map a realistic count before you start, so you're not left guessing halfway through.

Setting expectations up front also keeps the process from feeling stalled. Because the biggest gains show up weeks later, a plan with built-in check-in points is easier to stick with than chasing an overnight change that this kind of treatment isn't built to deliver.

What Are the Side Effects and Downtime?

Manageable for most people, but never zero, because no procedure is completely without trade-offs. On the day itself, expect redness and a faint grid pattern where the needles landed, plus a little puffiness that can linger into the next day. Most of it settles within two to three days.

Here's how the first week usually goes:

• Day of: wash with lukewarm water only, and hold off on makeup and saunas for the day.

• Days 2 to 3: if the skin flakes, don't pick at it; lean on moisturizer and sunscreen instead.

• After one week: reintroduce exfoliants and acids slowly from this point, not before.

A few signs are worth a message to the provider who treated you: redness that deepens rather than fades after a week, blisters or oozing, or new dark patches settling into the treated area. These aren't the usual course, but knowing them ahead of time means you'll act faster. If you ever notice spreading redness, fever, or worsening pain, seek medical care right away.

Sunscreen isn't optional here. Fresh collagen and healing skin are especially vulnerable to UV, and skipping it can undo the work. Never pick at scabs, however tempting.

The Bottom Line

If there's one thing to take away, it's that the shape of your scars matters more than the name on the machine. To recap:

• Three shapes, three behaviors: icepick, boxcar, and rolling scars sit at different depths.

• Secret RF favors some shapes: shallow boxcar and rolling scars tend to respond better than icepick.

• The mirror test helps: stretch the skin to see which shape leads before you commit.

• It's a slow build: plan for several sessions and give collagen a few months to catch up.

Like any procedure, this one comes with trade-offs, and it isn't a quick fix. Ultimately, the choice depends on your skin, your scars, and your goals, and the clearest way to sort your own mix is to have someone assess it in person. Beautystone is a dermatology clinic in Seoul's Hapjeong area; if you're weighing acne scar treatment, a consultation is the best way to find out what actually fits you. You can see current offers when you're ready.

Frequently asked questions

Q. Does Secret RF work on every type of acne scar?

A. Not equally. Because it works by remodeling the dermis, it tends to help shallow boxcar and rolling scars more than narrow icepick scars, which sit too deep and tight for the needles to reach well. Most faces have a mix, so the realistic goal is overall improvement in the shapes it suits rather than clearing every single mark. Individual results vary.

Q. How many Secret RF sessions do acne scars usually take?

A. Often several. In studies, sessions are spaced roughly four to six weeks apart, and because collagen keeps reorganizing, the change can keep improving for a few months after the final session. Mapping out the number and your check-in points before you start makes it easier to stay patient in the middle.

Q. Can I have Secret RF while I still get breakouts?

A. It's better to calm active acne first. Treating over inflamed skin can add irritation, and if new scars form where you just treated, the sessions end up spinning their wheels. Once your skin has settled, it's an easier time to start scar work, and your provider can help you judge the timing.

Q. When can I wear makeup after Secret RF?

A. Usually the next day, though it's more comfortable to wait one more day if redness and fine marks are still visible. During the flaky days two and three, focus on moisturizer and sunscreen rather than layering coverage on top. Because it depends on how much area was treated and at what intensity, the most accurate guidance comes from the clinic on the day itself.