HP 45A + Solvent Ink Cartridge + Black: Checks Before Buying

Two different products are sold under the same number, and the difference decides whether the cartridge you buy will print on the surface you actually code.

HP 45A is HP’s own part number, not a family name. It is the number on one specific black cartridge HP supplies for its deskjet-class printers — part 51645A, a pigment-based ink in a 42 ml TIJ 2.5 body with 300 nozzles. That is where the confusion starts: the original 45A is not a solvent cartridge, and it was never sold as one.

What we build is the same physical format, filled differently. Our XM-45S is an HP45-format TIJ 2.5 body — the same seat standard — filled with a fast-dry solvent carrier rather than a pigment-based deskjet ink. We are an independent manufacturer and not connected to HP; the name appears here only to identify the format you are searching for.

So the question splits in two. The format question decides whether the cartridge physically and logically fits your printer. The ink question decides whether the code holds on your material.

What “HP 45A” actually refers to

A part number describes one catalogue item, not a class of products. The 45A HP lists under 51645A is a deskjet and officejet-class item: 42 ml ink volume, a 300-nozzle printhead, a 33 pl drop, and a page yield measured on deskjet printing rather than on a production line.

That matters because the number is what a buyer has in hand. The cartridge that comes out of the machine carries the number, so the number becomes the search term — and every seller of a 45-format body then appears next to the original.

The 45-format seat itself is a genuine industry standard, the most widely used body in industrial thermal inkjet. The platform characteristics our cartridge publishes — 300 nozzles per row at 1/300 in pitch, drop volumes in the 29–38 pl range, fire frequencies in the 12–18 kHz band — are properties of that platform, not measurements taken on your material.

So when a supplier says “HP 45A”, ask which of the two things is meant: the original HP catalogue item, or a cartridge built to the 45-format seat. Both answers are legitimate. Only one describes a solvent system.

Why an original 45A is not a solvent cartridge

HP supplies 51645A as a pigment-based black for deskjet-class printing. That ink is built for absorbent paper, at office speeds, in a machine whose capping and wiping station is designed around it. It is not formulated to wet a low-energy plastic surface, and the printer around it is not built to stop a fast-dry solvent from setting in the nozzle plate between jobs.

A solvent carrier exists for the opposite problem. Carton and paper absorb a water-based code without argument; untreated polyolefins do not. Untreated PP measures around 26–28 mN/m and HDPE around 28–32 mN/m, both below the surface tension a water-based coding ink can wet reliably. A solvent carrier closes part of that gap — the fast-dry class sits near 23 mN/m static — which is why the same polypropylene cap that sheds a water-based code will hold a solvent one.

Two independent decisions are therefore bundled into one search phrase. The format decision is about the seat: 45-format, TIJ 2.5, half-inch or one-inch. The ink decision is about chemistry: pigment-based deskjet ink, or a solvent carrier built for a coding line. A cartridge can be right on the first and wrong on the second.

A third difference rarely appears in a listing: the original 45A is one black cartridge for printing on paper, while a commercial 45-format line offers the same seat in six colours and two print widths, because the industrial job is not the deskjet job.

What stays the same and what changes

Most of the differences sit in the ink and the chip rather than in the shape.

Attribute	Original HP 45A (51645A)	XinmoJet HP45-format solvent cartridge
Platform	TIJ 2.5, 45-format seat	TIJ 2.5, 45-format seat
Ink class	Pigment-based black, for deskjet-class printing	Fast-dry solvent carrier
Reference fill	42 ml	42 ml industrial fill
Printhead	300 nozzles, 33 pl drop	300 nozzles per row, 29–38 pl drop volume
Chip	HP OEM cartridge, printer-identifying	Non-encrypted / open chip, no authentication handshake
Print width	As supplied	12.7 mm and 25.4 mm from one platform
Colours	Black	Black, cyan, magenta, yellow, white and red
Made by	HP	XinmoJet, an independent manufacturer

Two rows decide most purchases: the ink class, because it decides whether the code holds on a non-porous surface, and the chip, because it decides whether your printer accepts the cartridge at all. Everything else is arithmetic or preference.

Will your printer accept it?

Two checks, independent of each other.

The physical check. A 45-format body comes as half-inch (12.7 mm) or one-inch (25.4 mm), and the carriage has to accept the size you order. Many compact handhelds take the half-inch only, so confirm before comparing prices — a cheaper one-inch cartridge the carriage will not hold is not cheaper. If the width is still open, the difference between 12.7 mm and 25.4 mm decides how much content fits in one pass.

The logical check. Some printers identify a cartridge before they will fire it: they read a chip, or run an authentication handshake. Ours is non-encrypted — open chip, no handshake, no single-use lock-out — which is what lets it be qualified as a second source alongside your existing supply without replacing printers. If your machine refuses non-OEM cartridges in firmware, establish that before any sample is sent.

A warning worth spelling out. A fast-dry solvent cartridge belongs in a printer built for it, with a capping station that tolerates solvent. Do not put one into a deskjet-class printer to see what happens. The original 45A and our cartridge share a seat standard, not a maintenance system, and solvent left sitting on a nozzle plate designed for something else will dry there.

If the printer model is unusual, say so and we will confirm it rather than assume. Where it cannot be confirmed from documentation, we would rather send a single cartridge for your operators to test than have you commit to volume on our word.

Why black, and when black is wrong

Black is the default for product coding because it gives the highest contrast on the surfaces that make up most packaging — natural and white HDPE, opaque PP, PET, coated aluminium. In industrial coding, contrast is not cosmetic: a verifier grades several parameters together and contrast is one, so a code that reads well to a human but weakly to a scanner can still fail a grade check.

Black is wrong when the product is dark. On black cable, dark blue closures or dark mouldings a black code carries no contrast and the eye has nothing to follow. That is the case for white ink, which our platform supplies in the same 45-format body at 300 dpi native. The test is not aesthetic: print both, then read the code with the scanner your customer will actually use.

Colour is not an adhesion fix. If a code fails because the ink does not wet the surface, that is a substrate and pretreatment question, and switching black to white changes nothing about it. The material-by-material version for containers and closures is at coding on plastic.

What black solvent changes on the surface itself

Three things decide whether a black solvent code holds, and none is the colour.

Surface energy. The first filter. Untreated PP and HDPE sit around 26–32 mN/m, below the surface tension of most coding inks, and you want a working margin of roughly 8 to 10 mN/m between the two. Where the gap is too wide the answer is pretreatment, not a different cartridge: corona or flame treatment lifts HDPE to roughly 38–42 mN/m and PP to 40–44 mN/m. Treatment decays in storage, so stock that has sat in a warehouse can behave differently from a freshly treated sample.

Drying budget. Measure the distance from the head to the first thing that touches the code, and divide by line speed. Solvent fast-dry typically sets in one to five seconds on a non-porous surface — a starting point, not a promise, since it depends on your ink load, ambient conditions and the roller doing the touching. If the budget is shorter than a few seconds, the fix is usually line layout rather than a different cartridge.

Adhesion after handling. A code that passes a fingernail test on a coupon can still fail on a packed carton that is rubbed, stacked and chilled. Print on the real substrate, stress the code the way the pack will be stressed, and use a recognised tape test such as ASTM D3359 rather than an opinion. If it fails, the sequence to diagnose it is fixed, and worth following in order.

Two caveats sit under all of this, and they are not disclaimers for their own sake: adhesion and drying are settled by a sample on your line, not by a datasheet. And the platform characteristics we publish — nozzle count, drop volume, throw distance in the 1–2 mm optimum range — are properties of the TIJ 2.5 platform, not measurements taken on your material. The full selection checklist, including how to price the result per usable pack, is worked through here.

Reading the phrase “HP 45A compatible cartridge”

In most listings it means one thing: the cartridge fits the 45-format seat. It does not mean the ink chemistry matches the original, that the fill volume matches, or that the printer will accept it without an authentication step.

Three questions separate a real answer from a label. Is the body new, or a reused original that has been flushed and refilled? What is the fill volume in millilitres, rather than in a page count? And which ink class is inside — pigment-based deskjet ink, or a fast-dry solvent carrier?

Those same three questions separate a new cartridge from a rebuilt one, which is a related problem with its own tells: how to tell a genuine HP45 cartridge from a rebuilt one covers what you can check in five minutes without equipment, and what you cannot check at all.

What to put in writing before you order

Six items. A supplier who answers all six has done the work; one who answers three has told you where the risk sits.

1. The printer make and model, and the cartridge seat it takes — half-inch, one-inch, or both.
2. The exact code content and character height. Cartridge life follows ink laid down per mark, not fill volume alone.
3. The substrate, named specifically. “Plastic” is not an answer; HDPE, PP, PET, rigid PVC and coated metal behave differently, and a dyne level for PP or HDPE settles the question.
4. The drying budget — distance in millimetres from the head to the first point of contact, plus the line speed.
5. A printed sample from the batch you will receive, ideally on your own material.
6. The fill volume in millilitres, and the replacement policy if a nozzle drops out inside the first month.

The commercial terms are short on our side. Standard orders carry a minimum of 160 units and ship within 3 working days of payment; published cartridge prices are EXW and exclude freight, and colours other than black are quoted individually. If you are still comparing suppliers, the questions that separate them are the same ones that make a quote comparison meaningful.

Where the decision usually lands

Four things settle a black solvent cartridge purchase, and only one of them is the cartridge.

Settle the format first: which seat the carriage takes, and half-inch or one-inch. Then the ink class, because a pigment-based deskjet cartridge and a fast-dry solvent cartridge are not substitutes on a non-porous surface. Then the colour against the substrate — black for light products, white for dark ones. Only then does the surface get a vote: surface energy, drying budget and adhesion after handling, all measured on your material.

The manufacturing scope, stated plainly because “HP 45A” makes it easy to assume otherwise: we make the cartridge and formulate the ink. The printhead is a component we qualify rather than manufacture. The printers are supplied with specialist equipment partners rather than built in our plant. How our TIJ ink cartridge manufacturing is set up covers the build, fill and test steps.

Send the printer model, the material and the code content, and we will tell you which of the two questions your problem belongs to — the format or the ink. You can reach us here with the sample or the specification sheet in hand.

Questions buyers ask about HP 45A solvent cartridges

Is an HP 45A solvent ink cartridge the same as an original HP 45A?

No. The original 51645A is HP’s black cartridge, supplied with a pigment-based ink for deskjet-class printing. A black solvent ink cartridge in a 45-format body is a different product: a new body filled with a fast-dry solvent carrier, for the non-porous surfaces a pigment-based deskjet ink was never formulated to wet.

Will an HP 45A compatible cartridge work in my printer?

Sometimes, and the two checks that decide it take minutes. Confirm the carriage accepts the body size you are ordering, and that the printer does not refuse non-OEM cartridges in firmware. Our cartridge is open-chip and non-encrypted, so it can be qualified alongside your existing supply; send the printer make and model and we will confirm it rather than leave you to find out.

Can I put a solvent cartridge into a deskjet-class printer?

We advise against it. A deskjet-class machine has a capping and wiping station designed around the ink supplied for it, and fast-dry solvent left on a nozzle plate that was not built for it will dry and clog. Solvent ink belongs in a printer specified for it.

How many marks will one 42 ml cartridge print?

That depends on character height and content density rather than on the 42 ml figure alone, and the range is wide: a single-line date code and a multi-line block carrying a QR code can differ several times over on the same fill. Send the actual code content and character height, and we will calculate it against your requirement instead of quoting a generic number.

Do you supply the original HP 45A?

No, and we do not claim to. We are an independent manufacturer: we build, fill and test 45-format cartridges ourselves, and we formulate the inks that go into them. If your machine needs an original HP cartridge, buy one from HP.