Materials

Spec Sheet for Custom Magnets That Ship Flat and Stick Right

Why Custom Magnets Fail in the Real World

The most common buyer complaint about custom magnets is not color mismatch or print blur. It is weak holding force, curl after transit, or a shape that looks fine on screen but fails on a filing cabinet, whiteboard, retail shelf, or refrigerator door. A magnet can pass a visual approval and still fail in use if the backing is too thin, the cut is off, or the laminate and magnet sheet fight each other after humidity changes. That is why a useful magnet spec has to cover graphics and functional performance together.

A magnet order should start by separating the application. Decorative fridge magnets mainly need clean print and a decent tack on painted steel. Office memo magnets need more pull and better edge stability. Promotional magnets that carry inserts, survive repeat handling, or sit in humid retail environments need tighter control over backing coverage, lamination, and flatness. Those differences change the structure, not just the price. A supplier quoting all three as the same product is usually quoting the cheapest version that may not meet the use case.

For procurement, the right question is not “Can you make a magnet?” It is “What exact stack will hold flat, survive shipping, and meet the stated pull test?” The answer should include thickness, substrate, magnet type, coverage, and a measurable defect limit.

Base Construction: The Stack You Are Really Buying

Most custom magnets are built from four elements: a printed face, an adhesive layer, a carrier or reinforcement layer, and the magnetic backing. The face may be paper, synthetic paper, PET film, or PVC. The carrier may be greyboard, thin plastic, or no rigid layer at all. The backing is usually flexible ferrite sheet or, less often, a thicker ferrite or rubberized magnetic compound. Each choice shifts stiffness, pull force, and cost. In practice, the stack matters more than the artwork file because it determines how the part behaves after lamination, die-cutting, packing, and repeated use.

A common flat fridge-magnet build is 157 gsm coated paper or 0.18 to 0.25 mm synthetic paper laminated to a 0.3 to 0.5 mm board, bonded to 0.4 to 0.8 mm flexible magnet sheet. Finished thickness usually lands around 1.0 to 1.8 mm. Heavier promotional pieces with full magnetic backing often run 1.8 to 3.0 mm total. Below about 1.0 mm, large pieces can feel flimsy; above 3.0 mm, freight cost and carton volume rise quickly. For very small magnets under 40 mm, the same build can still work, but the usable hold depends heavily on the contact area and surface condition.

Use case	Typical build	Practical note
Decorative fridge magnet	Printed paper or PET face + flexible magnet sheet	Lowest cost; suitable for light papers and short display runs
Office memo magnet	Printed face + thicker magnet backing + larger footprint	Better hold; edge curl becomes more important as size grows
Premium promo magnet	Rigid carrier + full-coverage magnetic backing	Flatter presentation; higher unit cost and freight density
Die-cut shaped magnet	Laminated print + flexible magnet sheet + custom knife	Best for branding; tool tolerance and registration matter most

A better way to compare quotes is by build intent. If two suppliers both say “1.5 mm magnet,” one may be using a 0.3 mm face plus 1.2 mm magnetic sheet, while another may be using a 0.2 mm face, 0.5 mm board, and a weaker magnetic layer. Those are not equivalent products, even if the total thickness matches on paper.

Magnet Type, Pull Force, and Coverage

Magnet grade is where RFQs are often too vague. Flexible ferrite sheet is the standard for promotional magnets because it is economical, easy to convert, and adequate for many light-duty applications. It is not a substitute for high pull force. When buyers need stronger retention, the factory may increase magnetic thickness, use a wider footprint, or cover more of the back face. The most useful spec is not “strong magnet”; it is the test condition and the result.

As a practical benchmark, a 50 x 50 mm flexible magnet on painted steel might hold one sheet of A4 paper comfortably, while a 90 x 90 mm magnet with a larger backing area can hold several sheets if the surface is flat and clean. If the part must hold through a calendar card, retail hang tag, or light brochure, ask for a stated pull test such as pull on 0.8 mm cold-rolled steel at zero gap. For flexible magnets, factories often quote pull in grams or newtons; either is acceptable if the test setup is defined. A clear requirement might read: minimum 180 g pull on 0.8 mm steel at 0 mm air gap, tested at five points per lot.

Coverage matters almost as much as material. Full-coverage magnetic backing improves flatness and grip consistency, but it adds weight. Partial-coverage backing lowers cost and may allow easier die-cutting, but it can create edge lift on larger shapes. If the design is over 80 mm wide or has long thin arms, ask the supplier to confirm the backing coverage percentage and whether reinforcement is needed in the weak zones. As a rule of thumb, full coverage is safer for parts above 100 mm on the long side, while 70 to 85 percent coverage can be acceptable on compact shapes if the test pull is still met.

For buyers comparing suppliers, the most useful magnetic specs are density, thickness, and test method. A flexible magnet sheet around 3.6 to 4.2 g/cm³ with 0.4 to 0.8 mm thickness is common for light promotional work. If the factory cannot say how it tested holding force, the quote is not yet technically complete.

Thickness, Weight, and Flatness Limits

Thickness controls more than appearance. It affects shipping cost, peel feel, dimensional stability, and whether the piece stays flat after it is unpacked. A part under 1.2 mm can feel too light if the face stock is soft or the backing is narrow. A part above 3.5 mm may feel premium, but it can be harder to pack tightly and more likely to develop visible edge lift if the adhesive bond is not uniform. For kits and mailers, thickness also affects how many units fit per carton and whether the pack stays within carrier dimensional weight limits.

For procurement, flatness should be written into the spec. A practical target is edge curl under 0.8 mm for pieces up to 80 mm wide and under 1.5 mm for larger formats, measured after 24 hours at 23 to 25°C and 45 to 60 percent relative humidity on a flat glass plate. For rigid-style magnets, a total warp or bow beyond 1.0 mm over 100 mm length is usually a reject unless the design intentionally curves. If the item is sold in blister packs or display cards, set a stricter limit of 0.5 mm curl for visible edges so the retail presentation stays clean.

Moisture control matters. Paper face stock absorbs and releases moisture faster than the magnet sheet, so warping often comes from mismatched humidity during lamination and storage. If the job uses paper, specify controlled conditioning before final inspection, and ask the factory to keep cartons off damp floors and away from direct heat. That simple instruction prevents a lot of “mystery curl” after sea freight. For humid destinations, it also helps to require sealed inner bags with desiccant and ship cartons held below 65 percent RH in the packing area.

If the article needs a flat premium look, ask for a target thickness tolerance of ±0.1 mm on the finished stack and a maximum thickness variation within a batch of 0.2 mm. That level is realistic for repeatable promotional work and helps avoid mixed-feel cartons.

Print Face, Lamination, and Image Durability

The print face controls both appearance and wear life. Paper with gloss lamination is still the lowest-cost route for high-volume promotions, and it gives sharp color at low unit cost. The tradeoff is scratch sensitivity at corners and seams. Synthetic paper, PET film, and PVC faces cost more, but they resist scuffing, moisture, and transit wear much better. For a fridge magnet that will be handled weekly, paper may be enough; for a magnet that will be wiped, packed with hard goods, or used in a humid retail setting, a synthetic face is usually the safer choice.

If the magnet will be handled often, specify the finish instead of leaving it open. Gloss lamination increases color density and hides minor print noise. Matte reduces glare, fingerprints, and visual distraction under retail lighting. For humid climates, cold-chain packs, or outdoor-facing displays, a UV-resistant overlaminate is the safer choice. Without it, ink fade and edge lift can appear within weeks even if the first inspection passes. A practical spec might call for 25 to 35 micron BOPP lamination on paper-faced magnets or a 12 to 20 micron PET overlaminate on higher-durability builds.

For exactness, buyers should name the print process too. Common options include offset printing for high-volume flat sheets, digital print for smaller lots or variable artwork, and UV printing for durable surface graphics. If the artwork has small type below 6 pt, fine gradients, or brand-critical colors, ask for a physical proof or calibrated digital proof against the final substrate, not just on screen. For brand work, a Delta E target of under 3.0 is a practical commercial benchmark, and under 2.0 is preferable if color matching is sensitive.

Concrete example: a 70 x 90 mm promotional magnet with a paper face, gloss lamination, and flex magnet backing can be a good fit for give-away campaigns. The same artwork on PET with matte lamination is a better choice if the magnets sit near kitchen steam or are touched repeatedly during retail browsing.

Die-Cut Accuracy and Shape Tolerances

Shape quality matters because magnets are usually judged by silhouette first. A perfect print on a rough cut still looks cheap. For standard round, square, or rectangle magnets, a dimensional tolerance of ±0.5 mm is reasonable at most commercial sizes. For more intricate custom profiles, ±0.75 mm is safer because knife wear, registration drift, and lamination shrinkage add up quickly. For complex profiles with tight internal corners, define the critical dimensions separately so the factory knows which edges are cosmetic and which edges must fit a tray, card, or insert pocket.

Internal corners and narrow necks need extra attention. Any bridge under 2.0 mm wide is vulnerable to tearing during converting or delamination when the magnet is peeled off steel. Small tabs, antenna-like shapes, and long arms should be reviewed with a die-making mindset, not only a graphic-design mindset. If the outline includes tight radii, ask the factory to confirm the minimum feature size before committing to tooling. A minimum internal radius of 1.5 mm is usually safer than sharp corners for flexible laminated magnets.

A good sample approval should verify both the silhouette and the stacking behavior. The sample should sit flat, separate cleanly from a release sheet if one is used, and survive repeated peel-and-reapply cycles without lifting at the edge. If the product will be sold in multipacks, also ask for nestability: some shapes catch on each other and scuff during packing even when the individual part is fine. A simple shop-floor check is 20 peel cycles on painted steel, followed by inspection for corner lift, print cracking, and magnet face scoring.

For conversion control, ask for die-cut tolerance by cavity or knife line if the order is larger than 5,000 pcs. Wear can drift across the run, and a supplier that tracks only the first sample may miss a late-run size shift.

Commercial Spec Table: What to Lock Before Quoting

Buyers get better results when the RFQ reads like a technical spec, not a concept note. The fields below are the ones most likely to move price, lead time, and functional performance. If they are not fixed, each supplier will interpret them differently and quote a different product under the same name. The most useful RFQ leaves no room for assumptions on thickness, magnet backing, or test method.

Spec line	Recommended buyer input	Why it matters
Finished size	Exact mm with tolerance, for example 85 x 55 mm ±0.5 mm	Controls die cost, fit, and nesting in cartons
Total thickness	Target mm and maximum limit, for example 1.6 mm target / 1.8 mm max	Affects curl risk, freight, and perceived quality
Face material	Paper, PET, PVC, or synthetic paper, with gsm or mm	Determines print durability, stiffness, and price
Magnet type	Flexible ferrite sheet or reinforced backing, with thickness	Sets pull force and weight
Print finish	Gloss, matte, soft-touch, or UV overlaminate	Changes scratch resistance and glare
Magnet coverage	Full back, 80 percent coverage, or partial backing	Affects flatness and holding power
Functional test	Hold one A4 sheet, three sheets, or defined pull force	Makes the buyer expectation measurable

A well-written RFQ also includes packaging detail, because packaging can change the acceptable flatness and the final freight rate. If the product must ship retail-ready, state inner count, polybag type, carton strength, and whether inserts are folded or flat-packed.

QC Checks That Prevent Rejections

A magnet order should be checked in three stages: artwork, first article, and packed goods. Artwork review confirms silhouette, bleed, and safe margins. First article review confirms thickness, cut accuracy, orientation, and bond integrity. Packed-goods review confirms flatness, surface scratches, carton crush resistance, and whether the pieces have shifted inside the box. Skipping one stage simply moves the problem downstream.

For inspection, a practical AQL starting point is 2.5 for major defects and 4.0 for minor defects on visible cosmetic issues, with tighter limits if the artwork is brand sensitive. For critical defects such as wrong magnet polarity, unusable pull force, or delamination, buyers should set a much stricter acceptance rule, often zero or near-zero tolerance by sample plan. If the order uses multiple dies or cavities, ask for samples from each cutting position because wear can differ across the run. For size-critical branded work, many buyers also cap the critical dimension at 0.65 mm max deviation even if the general dimensional tolerance is wider.

The main defects to watch are corner lift, bubbling, print scratching, magnet reversal, and weak adhesion between layers. If the product is ship-flat, add a simple transport test: pack a few units in a master carton, stack weight on top for 24 hours, then unpack and check for curl. That catches issues that may not show up in a short bench inspection. A practical transport check is 10 kg distributed load for 24 hours on a small carton or a palletized compression test if the order is shipping in bulk.

If the magnet will be applied and removed repeatedly, add a reuse check. A reasonable commercial target is no visible edge lift after 20 cycles on clean painted steel. If the finish is soft-touch or matte, check for scuffing under raking light because some surface damage only appears when the piece is viewed at an angle.

• Confirm finished size in mm, not just art size
• Specify total thickness and maximum warp or curl
• Name the face stock and lamination finish
• Define the magnet type, thickness, and coverage
• Request a stated pull-force or hold test method
• Set visible-defect AQL levels before production
• Approve one physical pre-production sample for new designs

Price Bands, MOQ, and Lead Time

For standard promotional fridge magnets, FOB pricing often lands around USD 0.18 to 0.45 per piece at 1,000 to 3,000 pcs for simple paper-faced builds with standard lamination and straightforward shapes. Thicker constructions, full-coverage magnetic backs, or more complex die-cut profiles commonly move into the USD 0.45 to 1.20 range at similar volumes. Premium multi-layer builds, soft-touch lamination, special packaging, or very small runs can rise above USD 1.20 per piece, especially when setup is spread over fewer units. At 5,000 pcs and above, simple repeat orders can sometimes drop to USD 0.12 to 0.30 FOB depending on size and finish.

MOQ usually follows tooling complexity and size. Simple round or rectangular magnets can start at 500 pcs, with better pricing at 1,000 pcs and up. Irregular die-cut shapes, multi-part sets, or heavy-layup magnets usually make more sense at 1,000 to 3,000 pcs because setup cost and waste are higher. If the order needs custom blister cards, inserts, or retail-ready packing, expect the MOQ to rise with the packaging component as well. A common packaging MOQ is 1,000 sets for printed inserts and 3,000 pcs for custom cards if the printer needs a separate setup.

Typical lead time is 12 to 18 days after sample approval for a straightforward run with existing tooling. New die-cut tools, special laminations, color matching, or multi-step assembly usually push that to 18 to 30 days. For urgent orders, some factories can compress production, but buyers should expect a cost premium and tighter artwork control. Shipping time is separate from production time, so FOB terms should be paired with a clear transit plan. If a die must be made from scratch, add 3 to 7 days for tooling before the production clock starts.

As a rough planning guide, a first-time buyer should treat 500 to 1,000 pcs as a qualification lot, 1,000 to 3,000 pcs as the normal commercial band, and 5,000 pcs or more as a volume run where per-unit cost starts to improve meaningfully. If the design is still under review, it is usually smarter to buy one small lot first than to lock into a large run with an untested magnet stack. For repeat SKUs, the best savings usually come from freezing the spec, not from chasing the absolute lowest quote on the first order.

If you need a useful quote comparison, ask every supplier to quote the same basis: FOB port, 1 design, exact size, exact thickness, same lamination, same carton pack, and same pull test. Otherwise the price spread will mostly reflect different assumptions rather than true manufacturing cost.

What to Do Next

Turn the concept into a one-page spec before asking for quotes. Lock the finished size, total thickness, face material, magnet type, print finish, target pull performance, and acceptable curl limit. Then request a sample, a photo of the production stack, and the factory’s QC method before mass-run approval. That leaves less room for substitutions and gives you a clean basis for comparing offers.

If you already have artwork, the fastest quote request includes a dimensioned drawing, target quantity, destination country, packaging requirement, and the performance target, such as one-sheet hold or three-sheet hold. If the magnet must pair with other promotional items, align the spec across the whole program so the print quality, carton size, and lead time stay consistent from item to item. A complete RFQ usually shortens back-and-forth by several days and reduces the chance of a sample that looks right but performs wrong.

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