What is a slipmat, and do you actually need one?

A slipmat is a disc of felt that sits between the platter of your turntable and the record on top of it. It is the least conspicuous part of a hi-fi system, one of the few you can change in a second with no tools, and the only one that touches your records every single time you play them.

What does a slipmat actually do?

It does three things: it lets the record slip, it damps vibration, and it protects both surfaces. In that order of how much you will notice.

It reduces friction. A record sitting on a bare metal or acrylic platter is held by nothing but its own weight. Felt gives the record a surface to grip without binding to it, which is what lets a DJ hold a record still while the platter keeps turning underneath. That is where the name comes from, and it is the whole basis of beatmatching.

It damps unwanted vibration. A platter is a rigid disc being spun by a motor. It rings, faintly, and that ringing reaches the stylus as noise that was never cut into the record. Felt between the two absorbs some of it before it arrives. If you want to see why the stylus is so sensitive to this, PS Audio's explanation of how one needle reads two channels is four minutes well spent.

It protects the surface. Both surfaces. Grit on a bare platter gets pressed into the label side of every record you play. A mat takes that abuse instead, and is far cheaper to replace than a record.

Do you need one?

If your turntable came with something on the platter, you already have one, and the real question is whether it is any good. A thin, loose, low-density mat does the third job and very little of the first two.

You will notice a better one most if any of these are true:

• Your records cling to the mat and lift it off the platter when you pick them up. That is static, and a denser, higher-compression felt holds less of it.
• The mat has gone fuzzy or sheds. Low-compression felt pills, and the pills end up on the record.
• You mix, or cue by hand. Then the slip is the entire point, and a thin mat binds.
• Your deck shares a surface with a speaker. Then damping matters more than usual.

What should you look for?

Four numbers tell you most of what you need to know about a mat.

Diameter. A twelve inch LP is 302 mm across. A mat should sit just inside that, so the record covers it and nothing catches the edge. Ours is 298.5 mm, which leaves 1.8 mm of record overhanging the whole way round.

Thickness. Enough to damp, not so much that it changes your tracking. 3.18 mm is a working figure. Change thickness by much and you may want to reset your tonearm height.

Areal density. Felt is sold by weight per unit area, in ounces per square yard. The standard that ships with most decks is sixteen ounces. Ours is twenty-one, which is 712 g/m², and the difference is immediate under the hand.

The reverse. Plain and unglazed is what sets the slip. A coated back grips the platter, which is the opposite of what a slipmat is for.

Why does felt weight matter so much?

Because density is what separates a mat that works from a disc of fabric. Felt is made by matting fibres together under heat and pressure rather than weaving them, so how hard it was pressed decides how it behaves.

Twenty-one ounce felt at 3.18 mm works out at roughly 0.22 g/cm³. That is a normal needled-felt density, and it is dense enough to lie flat, resist pilling and hold its shape through hundreds of plays. Press the same weight into half the thickness and you get something closer to hard industrial felt, which damps less and slips differently.

Why do records pick up static, and what helps?

Static comes from the triboelectric effect: two materials in contact exchange charge when they separate. A vinyl record lifted off a felt mat in a dry room is exactly that, which is why the mat sometimes comes up with it.

Three things reduce it, in order of how much they help:

• Humidity. Static is a dry-air problem. Above roughly 50% relative humidity it largely stops being one.
• A denser felt. High-compression felt has less loose surface fibre to charge and shed.
• A grounded turntable. Charge needs somewhere to go.

How is a printed slipmat made?

Most printed mats are printed on: ink sits on the felt as a layer and you can feel it under a record. Dye-sublimation dyes the fibre instead, so there is nothing on the surface at all, nothing to lift, and nothing between the record and the felt.

It is the difference between a mat that happens to have artwork and a mat that is the artwork. It is also why a custom run is possible: if the ink is in the fibre, your design is as durable as the mat. Ours are printed that way, one face or both, at the spec on this page.

How do you look after one?

Keep it flat and keep it clean. Felt loses its structural integrity when it is rolled, which is why every mat we ship travels flat inside a record jacket rather than in a tube.

For the records themselves, the Library of Congress preservation guidance is the reference worth reading: handle discs by the edge and label only, store them vertical, and keep the room cool and not too dry. Wikipedia's summary of conservation and restoration of vinyl discs covers the same ground with citations.

Where did the slipmat come from?

From a problem, in the Bronx, in the 1970s. Grandmaster Flash wanted to rewind a record to the start of a break while the platter kept spinning, and nothing on the market let him do it. He lined the underside of the record with felt and waxed paper, and the slipmat existed.

What Hi-Fi's feature on the man who gave us the turntable as an instrument is the best short account of how that one piece of felt turned a playback device into something you play. The direct-drive turntable is the other half of the story: you need a motor that recovers instantly for any of it to work.