Check Protector and Writer Tools: Complete Security Guide

What a Check Protector Is

Checkwriter definition: a check protector, also known by the synonymous names checkwriter, ribbon writer, check embosser, check writer machine, and check signer, is a device designed to imprint the dollar amount onto a check in a form that is very difficult to alter. The ANSI/ASB Standard 172 (2024 Edition) defines a checkwriter as "a device manually or electrically-powered or computer-generated, designed to ink, emboss, print, perforate, or shred a monetary value, along with other peripheral information, onto a document."

Check protector definition: a check protector physically attacks the paper fibers in the amount field of a check, shredding them and forcing indelible ink into the resulting disruption. Because the paper itself is damaged in the process, amount alteration prevention is the core purpose: any later attempt to chemically wash or mechanically erase the amount causes visible, irreparable damage to the check. The amount field essentially cannot be cleanly altered after being processed through a check writer.

This check embosser machine is positioned over the amount field of the check. The operator enters the payment amount using levers or buttons. A mechanism then drives inked print heads through a colored ribbon and into the paper surface with significant downward force. The result is an imprint that is part ink, part physical disruption of the paper fibers, and part embossed impression visible from both sides of the check.

How Check Protectors and Writers Work Mechanically

The mechanical process of a check writer is more sophisticated than it appears. Understanding it explains why check writers provide stronger amount protection than standard ink writing, and why they were the primary check security tool for most of the 20th century before electronic check security emerged.

The Imprinting Mechanism

As a check fraud prevention tool, the check writer contains a set of character print wheels carrying numerals and symbols. When the operator enters an amount, the relevant print wheels rotate to position. The operator then pulls a lever (on manual units) or presses a button (on electric units), which drives the print heads downward through an inked ribbon onto the check paper beneath.

The force applied is considerably greater than standard printing or writing. The print heads do not merely deposit ink on the paper surface; they physically compress, shred, and perforate the paper fibers in the amount field while driving indelible ink into those disrupted fibers.

The Prefix and Suffix Protection

Beyond the mechanical damage to the paper, check writers add text protection against digit inflation. When you enter $6,762.64, the machine does not simply print "6762.64." It produces text such as "TheSum6762dol's64cts" with words before and after the numerals that fill the available space and prevent a fraudster from adding digits at either end to inflate the amount. This prefix and suffix system, established in the early 20th century, closes the gaps that a simple numerical imprint would leave.

The Embossing Element

Many check writers also emboss the amount through the paper, creating a raised or indented impression visible and tactile from both sides of the check. This embossed impression is independent of the ink and cannot be removed without leaving an obvious trace of the original impression in the paper. Even if an attacker somehow removed all the ink, the physical embossing would remain as evidence of the original amount.

Types of Check Protectors: Punch, Perforator, Ribbon Writer

Check protection technology has evolved through several distinct mechanical approaches since its invention in the mid-19th century. These different types are still relevant for understanding what a check writer does and how it differs from alternatives.

Check Punch

The earliest mechanical check protectors (late 19th century) used a punch mechanism that cut holes in the shape of numerals through the check paper. A check punch produced amounts by physically removing paper in the numeral shapes. The resulting holes could not be filled in, making the amount visible from both sides. However, holes could be covered, which made punches somewhat less secure than later methods.

Check Perforator

Check perforators used a mechanism that punched small round holes (rather than numeral-shaped holes) arranged to form numerals. The perforated pattern was harder to conceal than large numeral holes. Perforators were widely used by the US Treasury and government agencies for check protection in the late 19th and early 20th centuries.

Ribbon Writer (Shredding Writer)

The ribbon writer, introduced commercially around 1914 by Hedman Manufacturing with the F&E Check Writer, became the dominant form of check protection through most of the 20th century. The ribbon writer does not punch holes; instead it forces ink through a ribbon into shredded paper fibers. This "shredding principle" (as described in the 1926 Office Appliance Manual) produces an amount that is simultaneously printed and physically embedded in disrupted paper fibers.

The ribbon writer's advantage over punch and perforator systems is that the amount is rendered in both color and texture, with multicolor ink in disrupted fibers that cannot be chemically washed without destroying the check visibly. The Hedman F&E, described at the time as "not a mere check writer, but an absolute, 100% prevention of loss through alteration of your checks," established the standard that Paymaster Corporation later refined into its long-running product line.

History of Check Writers From 1914 to Paymaster

The history of check writers is the history of the fraud arms race between businesses issuing checks and criminals who raised, altered, or forged them. Understanding that history explains the design choices that make modern check writers effective and why they remain in use today.

Check fraud statistics and history: check fraud in the late 19th and early 20th centuries was described in the trade literature as "one of the gravest and most widespread of all menaces against our nation's business." The primary attack was "raising" checks: altering a check for $6 to read $600 or $6,000 by adding digits or altering handwritten words. Standard handwritten amounts in ink provided no meaningful resistance to skilled check raisers who could wash, scrape, or chemically treat the original amount.

The Hedman Manufacturing Company's F&E Check Writer of 1914 introduced the commercial figure-writing shredding approach. By 1917, competitors including Safe-Guard had developed similar machines. By the 1920s, the safety paper and mechanical check writer combination was recognized as the effective solution: "Where this method of protection has been adopted, to date, there has not been a single case of loss from forgery or alteration" (Burgess Smith, 1922).

Paymaster Corporation, founded in the early 20th century, became the most recognized American check writer manufacturer. Its "Paymaster Check Writer and Protector" became a commercial success through the 1930s depression era and beyond. Paymaster added locks and keys to its machines in the 1950s as security concerns grew. Paymaster check writers remain in regular use today at the US Postal Service for money orders and at financial institutions for cashier's checks, despite the company itself having closed by 2000. The Paymaster brand name continues under successor organizations.

Modern Use Cases for Check Writers

Physical check writers are now considered specialized equipment rather than standard office tools. Most businesses that previously used check writers have shifted to accounting software with MICR printing on ABA-compliant security stock. However, specific use cases remain where physical check writers serve an important function.

Money Order Production

The US Postal Service uses check writers to produce money orders. The mechanical amount imprinting provides the same physical alteration resistance for money orders that it historically provided for checks. Financial institutions use similar equipment for cashier's checks.

High-Value Manual Check Writing

Businesses or organizations that write high-value checks manually (rather than through software) and cannot accept any risk of amount alteration use check writers as a supplement to handwriting. A $50,000 payment written by hand with a gel ink pen carries some washing risk; the same amount processed through a check writer carries near-zero alteration risk from chemical or mechanical attack.

Sole Proprietors and Small Organizations

Some sole proprietors, nonprofits, and small organizations that write manual checks for payments prefer the additional protection of a check writer over pen writing alone. The check writer's mechanical imprint provides a level of assurance that the amount is locked in.

For most businesses writing checks through accounting software, the check writer is made redundant by the security features built into ABA-compliant security stock. The chemically reactive paper, void pantograph, and other features address the same fraud vectors through the paper itself rather than through a separate mechanical device.

The Gel Ink Pen and Check Washing: What the Experiments Show

The gel ink pen check washing recommendation is widely repeated in financial security guidance. The recommendation to write checks with gel ink pens to prevent check washing is widely repeated in financial security guidance. The actual experimental evidence is more nuanced than most guides acknowledge, and the honest assessment is important for anyone relying on a pen as their primary check protection.

The Uni-ball 207 Experiment

In a widely referenced check washing experiment conducted independently by financial security researchers and the OrboGraph Check Fraud Roundtable, several pen types were tested against common check-washing solutions. The Uni-ball 207, with its proprietary Uni-Super Ink, performed best: its pigment ink did not budge under any of the solutions tested. The Uni-ball 207 is the most consistently recommended gel pen for check writing by fraud prevention professionals.

The Pilot G2 Result

The Pilot G2, which has a strong reputation as a premium gel pen, was effectively washed by "Solution B" and faded under another solution in the same tests. This is a significant finding because the Pilot G2 is often cited as a check-writing recommendation without testing. Not all gel pens are equivalent for check washing resistance. The specific ink formulation matters, not just the "gel" category.

The Nuance: Persistence Does Not Mean Impossibility

OrboGraph researchers found that even the best-performing gel pens could have their ink scrubbed off with sufficient physical effort (using a toothbrush with solution) with damage that might not be detectable in a mobile deposit capture image processed in black and white. The gel pen makes washing harder, not impossible. It raises the difficulty bar and increases the chance of visible damage, but a determined fraudster with the right tools can still remove gel ink from checks.

The OrboGraph analysis frames gel pens correctly: they are one tool that makes check washing more difficult for opportunistic criminals, but they are not a complete defense. They should be combined with ABA-compliant security paper, secure mailing practices, and account monitoring.

Best Pens for Writing Checks

The check washing prevention pen category includes several options. Based on wash-resistance testing and expert recommendation, here are the pen characteristics and specific models most effective for check writing security.

Uni-ball 207 (Top Recommendation)

The Uni-ball 207 uses Uni-Super Ink, a proprietary pigment-based gel ink specifically designed to resist check washing. In the most rigorous independent tests, it was the only pen whose ink did not react to any of the washing solutions tested. It is available at most office supply retailers and drug stores for under $3 per pen.

Zebra Sarasa

The Zebra Sarasa line uses Rapid Dry Ink technology that dries in under one second, reducing smear risk for left-handed writers. The pigment-based ink provides strong check washing resistance and is water-resistant and fade-resistant.

Pilot Precise V5/V7

The Pilot Precise uses pigment-based liquid ink (not a gel) that bonds strongly with paper fibers. It is a rollerball format rather than a gel format but provides similar fiber-bonding resistance to washing.

What to Avoid

Standard ballpoint pens with oil-based ink (oil-based ink vulnerable pens) are the most vulnerable to check washing. The oil-based ink sits on the paper surface rather than bonding with the fibers, and washes off more easily with chemical solvents. Felt-tip pens (including many permanent markers) are also vulnerable because their dye-based inks dissolve in solvents rather than bonding with fibers.

Why Ballpoint Ink Washes Off and Gel Ink Does Not

The difference in check washing resistance between ballpoint pens and gel ink pens comes down to the ink composition and how it interacts with paper.

Ballpoint pens use oil-based ink. Oil-based inks are viscous and deposit on the surface of the paper. They do not penetrate deeply into the paper fibers. When a washing solvent is applied to a check written with a ballpoint pen, the solvent dissolves the oil-based binder in the ink, lifting the pigment or dye off the paper surface. The surface remains relatively undamaged because the ink never fully integrated with the paper fibers to begin with.

Pigment ink check writing: gel ink pens use water-based gel carrying pigment particles (solid particles suspended in the gel, not dissolved dyes). The pigment ink fibers mechanism: when gel ink is applied to paper, the water carrier is absorbed by the paper fibers, drawing the pigment particles into the fiber structure. As the gel dries, the pigment particles become embedded within the paper fibers rather than sitting on top of them.

Attempting to wash gel ink with a solvent requires attacking the paper fibers themselves to remove the embedded pigment. This physical disruption is visible as damage to the paper: discoloration, texture change, or tearing of the fibers. A check that has been washed to remove gel ink will show these signs of tampering at the point where the washing occurred.

The ballpoint vs gel ink difference is relevant only for check washing (chemical removal of existing ink). It is not relevant for digital counterfeiting, forgery, or any fraud that does not involve altering an existing check.

What Gel Pens Cannot Protect Against

This is the most important security gap that most gel pen recommendations omit, and understanding it is essential for building a complete check security approach.

Digital Counterfeiting

The dominant fraud trend identified by OrboGraph and other fraud researchers is a shift from check washing toward digital counterfeiting. In digital counterfeiting, the fraudster scans a stolen check to extract the routing number, account number, and the account holder's signature. These elements are then used to create new check documents on a computer using desktop publishing software, printed on any printer, for any amount, in unlimited quantities.

A gel ink pen provides zero protection against this attack. The fraudster never touches the original check's amount field. They create entirely new checks from the extracted data. No amount of ink resistance prevents a new check from being printed with a digital copy of your signature and your account number.

Forgery of the Signature

A forged signature fraud involves a thief who signs your name on a blank check using their own pen. Your gel ink pen in your drawer provides no protection against someone else signing a blank check with any pen they choose.

Physical Theft of Blank Checks

If your checkbook is stolen, the thief can write any amount they choose on the blank checks using any pen, including a gel ink pen. The gel ink protection applies only to checks you have already filled out.

These limitations are why the full check security stack matters: gel ink pen (washing resistance) + ABA-compliant security paper (washing, counterfeiting, and alteration resistance) + secure mailing practices + account monitoring. Each layer addresses fraud types that the others cannot fully cover.

What Check Washing Is and How It Works

Check washing is the fraudulent process of using chemical solvents to remove the ink from a legitimate check without damaging the paper, then rewriting the payee name and dollar amount for fraudulent purposes. It is one of the oldest and most persistent forms of check fraud.

The typical check washing scenario begins with mail theft. A criminal removes envelopes from residential mailboxes or USPS collection boxes looking for envelopes that appear to contain checks. Personal payment envelopes (for rent, utilities, charitable donations, bills) are the most common targets. The stolen check is placed in a chemical bath or treated with solvents such as bleach, acetone (nail polish remover), or commercial cleaning products.

If the check paper and ink are not resistant to these solvents, the ink dissolves and the check emerges with the paper intact and the signature already in place. The fraudster then rewrites the payee name (changing it to themselves or a money mule) and alters the amount. The altered check is then deposited, often at a different institution from where the account is held.

For a complete guide to preventing check fraud including check washing, forged endorsements, and account monitoring, see our check fraud scams guide and our check validity and fraud prevention guide.

How ABA Security Paper Prevents Check Fraud

ABA-compliant check security paper features form the foundational protection layer that addresses the fraud types that gel pens, check writers, and other tools cannot fully cover. Every Checkomatic check ships on this security paper with all six standard features included at the base price.

Chemically Reactive Paper (Check Washing Prevention)

Chemically reactive paper contains agents that react permanently when contacted by the solvents used in check washing. When bleach, acetone, or similar chemicals touch the paper, a visible, permanent stain appears that cannot be concealed or reversed. A bank teller or automated imaging system immediately identifies the check as tampered. This is the paper-level equivalent of what a gel ink pen attempts to achieve with ink alone, but it applies to the entire check surface rather than only the written areas.

Genuine Foundry Watermark (Counterfeiting Prevention)

A watermark embedded in the paper fiber during manufacturing is visible when the check is held to light. No desktop printer or office copier can reproduce a genuine foundry watermark because it is a structural property of the paper, not a surface print. This directly addresses the digital counterfeiting threat: a check printed from a computer on plain paper or even high-quality paper cannot duplicate the genuine watermark, making counterfeits detectable by any bank teller or automated system with UV or transmitted-light verification.

Microprinting (Copying Prevention)

Text printed at a scale requiring magnification to read appears as a solid line to the naked eye along the signature line. Photocopiers and scanners cannot reproduce microprinting accurately; any copy shows a blurred, indistinct line rather than readable text. This makes photocopied or digitally scanned counterfeits detectable at the microprint location.

Heat-Sensitive Thermochromic Ink (Authentication)

An area of the check face printed with ink that disappears when warmed and returns when cooled allows instant authentication. A bank teller rubs the area; on a genuine check, the ink vanishes. On a counterfeit printed on plain paper, no thermochromic zone exists.

Void Pantograph (Copy Detection)

A background pattern that produces visible VOID text when the check is photocopied, scanned, or imaged directly addresses the digital counterfeiting workflow. When a fraudster scans a check to extract the routing number, account number, and signature, the resulting digital image reveals VOID across the check background. Any check printed from this image carries the VOID pattern, identifying it as a copy.

UV Fluorescent Fibers (Authentication)

Fibers distributed through the paper that glow under ultraviolet light distinguish genuine security paper from plain paper immediately. A counterfeit printed on standard paper has no fluorescent fibers and fails this test.

For the complete technical guide to how each security feature works against specific fraud types, see our check stock paper guide and our check fraud prevention guide.

The Layered Check Security Approach

Check writing best practices require multiple layers. No single check security tool addresses every fraud type. Business check security tools work best in layers. The effective check security approach uses multiple layers, each targeting the fraud types the others cannot cover.

Layer 1: ABA-Compliant Security Paper

In a check protector vs security paper comparison, the security paper is the most important foundational layer. Chemically reactive paper catches check washing. The void pantograph and genuine watermark address counterfeiting. Microprinting prevents copy-based fraud. This layer is built into every check you order from Checkomatic at no additional cost.

Layer 2: Gel Ink Pen for Manual Writing

For checks written by hand rather than printed through software, a pigment-based gel ink pen (specifically the Uni-ball 207 for best washing resistance) makes the written fields harder to chemically remove. This is a secondary layer that complements the paper security features rather than replacing them.

Layer 3: Check Writer for High-Value Manual Checks

For manual check security, businesses that write high-value checks manually and want the strongest amount-field protection, a mechanical check writer adds check amount field protection, a physical disruption layer that makes amount alteration nearly impossible even for a skilled fraudster. This layer is most appropriate for manual check writers issuing checks in large amounts.

Layer 4: Secure Mailing Practices

Dropping checks directly at a post office counter (not a street collection box) and using security envelopes with dark interior tinting prevents the initial theft that enables check washing. A fraudster cannot wash a check they never obtained. This layer prevents the theft that makes washing possible.

Layer 5: Account Monitoring

Reviewing cleared check images through online banking catches alterations and forgeries that passed through the banking system. Comparing the payee name and amount on the cleared image against your check register entry identifies fraud that slipped through other defenses. For businesses, positive pay automates this comparison for every check presented.

For more on how the complete check fraud prevention system works, see our check validity and fraud prevention guide and our check fraud scams guide.

Why Order Checks From Checkomatic

Checkomatic has manufactured personal and business checks in Monroe, NY since 1997. As an in-house check manufacturer, Checkomatic produces every order at its Monroe NY facility with direct quality control over the security paper, MICR encoding, and print quality.

ABA Security Paper Standard on Every Order

Every Checkomatic check, whether personal or business, ships on ABA-compliant check paper (ABA compliant check paper) with all six fraud deterrent features at the base price. There is no security tier to upgrade. The CPSA certified designation on Checkomatic's ordering pages confirms compliance with Check Payment Systems Association standards.

These six features provide the paper-level protection that complements whatever writing tool the account holder uses. A check written with a Uni-ball 207 on Checkomatic security paper has gel ink resistance to washing AND chemically reactive paper resistance to washing, AND void pantograph counterfeiting detection, AND genuine watermark authentication, AND microprinting copy detection.

Full Personal and Business Check Range

Checkomatic manufactures personal checks, business computer checks, manual business checks, QuickBooks checks, and blank check stock. All formats for manual check writing, where a check writer or gel ink pen is most relevant, are available:

• Manual business checks (accounts payable, payroll, multi-purpose, deskbook, pocket)
• Personal checks (standard, top stub, deskset, secretary deskbook)
• Blank check stock for MICR printer operations

Free Logo Printing on Every Order

Free black and white logo printing is included on every personal and business check order. Color logo printing is available for a small additional per-order charge. No setup fee. Standard turnaround is 3 to 5 business days from digital proof approval.

Order at checkomatic.com. For the complete guide to check security features built into Checkomatic's paper, see our check stock paper guide. For the EZShield fraud recovery service that some check printers offer as an add-on, see our EZShield check security guide.

The Short Version on Check Protector and Writer Tools

A check protector (checkwriter, ribbon writer, check embosser) is a mechanical or electric device that imprints the dollar amount onto a check by shredding paper fibers and forcing indelible multicolor ink into the disrupted area, with prefix and suffix text that prevents digit inflation. Amount alteration on a check writer-protected check requires visibly destroying the check. Mechanical check writers are most relevant for high-value manual check writing; most businesses printing through accounting software are better served by ABA security paper.

The best pen for check writing is the Uni-ball 207, which performed best in wash-resistance experiments. Standard ballpoint pens use oil-based ink that sits on the paper surface and washes off more easily; pigment-based gel ink bonds with paper fibers and is harder to remove. Gel pens resist check washing only: they provide no protection against digital counterfeiting, forgery, or blank check theft.

ABA-compliant security paper addresses check washing (chemically reactive paper), counterfeiting (genuine watermark, void pantograph), and copying (microprinting) at the paper level. Every Checkomatic check ships on this security paper with all six features at the base price.

Frequently Asked Questions

What is a check protector?

A check protector, also called a checkwriter, ribbon writer, check embosser, or check writer machine, is a mechanical or electric device that imprints the dollar amount onto a check in a form that is very difficult to alter. The check protector definition from ANSI/ASB Standard 172 (2024) describes it as a device designed to "ink, emboss, print, perforate, or shred a monetary value onto a document." The machine presses print heads through an inked ribbon into the paper of the check, shredding the paper fibers under the amount field and forcing indelible ink into the disruption. Any attempt to chemically remove or erase the imprinted amount visibly damages the check. Prefix and suffix text is added around the numerals to prevent adding digits at either end to inflate the amount.

What is the best pen to write checks with to prevent fraud?

The best pen for writing checks to resist check washing is the Uni-ball 207, which uses Uni-Super Ink (a proprietary pigment-based formulation). It performed best in multiple wash-resistance experiments, with its ink not reacting to any washing solutions tested. The Pilot G2, despite its reputation, was effectively washed by certain solutions in the same tests. Standard ballpoint pens (oil-based ink) are the most vulnerable to check washing because oil-based ink sits on the paper surface and washes off more easily. Pigment-based gel ink bonds with paper fibers, making removal require physical damage to the paper that is visible at the washing site. For complete protection, gel ink pens should be combined with checks on ABA-compliant security paper.

Do check protectors still work and are they still available?

Yes, mechanical and electric check protectors work as designed and remain available for specialized uses. The US Postal Service uses check writers for money orders, and financial institutions use them for cashier's checks. New electric check writers are still manufactured in smaller quantities for businesses issuing high-value checks manually. The Paymaster brand, historically the most recognized US check writer manufacturer, has successor organizations that continue the product. For businesses printing checks through QuickBooks or other accounting software, MICR check security through MICR printing on ABA-compliant security stock has largely replaced the physical check writer by providing the same fraud protection through paper-level security features.

What is check washing and how does security paper prevent it?

Check washing is a fraud method where criminals use chemical solvents (bleach, acetone, alcohol-based cleaners) to remove ink from a stolen check without damaging the paper, then rewrite the payee and amount for unauthorized use. Fraudsters typically steal checks from residential mailboxes or USPS collection boxes. Chemically reactive security paper prevents effective check washing by containing agents that produce a permanent, visible stain when washing solvents contact the paper. This makes the tampering immediately obvious to a bank teller or automated image system. The stain cannot be removed or concealed. Combined with a void pantograph (reveals VOID text when scanned), genuine watermark, microprinting, thermochromic ink, and UV fluorescent fibers, ABA security paper addresses check washing and counterfeiting at the paper level.

Does Checkomatic sell check protectors or check writers?

Checkomatic does not sell mechanical check protectors or electric check writers. Checkomatic manufactures personal and business checks on ABA-compliant security paper with six built-in fraud deterrent features: chemically reactive paper, genuine watermark, microprinting, heat-sensitive thermochromic ink, void pantograph, and UV fluorescent fibers. These paper-level features address check washing, counterfeiting, and copying at the manufacturing stage. Businesses that write high-value checks manually and want additional amount protection can use a third-party mechanical check writer alongside Checkomatic's security check stock. The combination provides both paper-level protection from the ABA security features and mechanical amount protection from the check writer.