Standard Resin
GENERALThe default for visual prototypes and models. Fine detail, smooth finish, stable dimensions, and the lowest cost per part of any resin we run. Stiff and brittle — it is not a load-bearing material.
Fine detailSmoothLow cost
MATERIAL · RESINS
Photopolymer Resins — Six Families, and They Are Not Interchangeable
A photopolymer is a liquid resin that cures into a solid plastic under ultraviolet light. SLA resolves detail no other process touches — 50 µm layers, ±0.1 mm tolerance, legible engraved text and transparent parts — but "resin" is not one material. Standard, tough, high-temperature, biocompatible, castable and clear resins behave completely differently, and choosing the wrong family is the most common reason a printed part disappoints.
50 µmTypical layer height
±0.1 mmTypical tolerance
~80 °CHeat deflection
6Resin families
OVERVIEW
What a photopolymer actually is
Photopolymers are oligomers and monomers carrying photoinitiators. The initiator absorbs UV light and starts a chain reaction that cross-links the liquid into a solid network. In SLA a laser traces each cross-section on the surface of a resin vat, curing one layer in seconds, and the platform drops by one layer height before the next pass. Because the light is focused and the material is liquid, the achievable detail is set by the laser spot and the layer height rather than by the mechanics of a nozzle or a powder bed — which is why layer lines are measured in microns and why internal channels, engraved text and 0.2 mm features come out legible.
The critical fact that gets missed is that the cure is not finished when the part leaves the machine. A freshly printed part is only partially cross-linked: it is soft, and it will not reach its published mechanical properties until it has been post-cured in a controlled UV chamber. Skipped or improvised post-cure is far and away the most common cause of "my resin part is still soft". Every part we ship is post-cured under a governed cycle, and the heat deflection and strength figures quoted here assume that has happened.
Then there is the choice of family, which changes everything. A standard resin is stiff, cheap and brittle. A tough resin is considerably more impact-resistant and is the one that survives being dropped. A high-temperature resin holds stiffness well above the ~80 °C ceiling of the standard grades. A castable resin burns out cleanly in a lost-wax investment cycle. A clear resin polishes to optical transparency. A biocompatible resin is qualified for anatomical models and surgical guides. Same process, same machine, completely different service behaviour — which is the reason this page leads with the families rather than a property table.
PROPERTIES
The Six Resin Families, Compared
These are the families we stock and run. The right question is not "is resin strong" but "which family behaves like the part I am designing".
| Family | Strength | Elongation | Heat | Pick it when |
|---|---|---|---|---|
| Standard Resin | Stiff, brittle | Low | ~80 °C | Visual prototypes, models, masters — detail and cost matter, load does not |
| Tough / ABS-like | High impact | Moderate–high | ~80 °C | Snap-fits, housings, parts handled daily, functional checks |
| High-Temperature | Stiff | Low | Well above the standard ceiling | Mould inserts, hot-air ducting, anything near a heat source |
| Biocompatible / Medical | Stiff | Low–moderate | ~80 °C | Anatomical models, surgical and drill guides, dental models — non-implant |
| Castable | Low — it is a pattern | Low | ~80 °C | Lost-wax investment casting: jewellery, small metal components |
| Clear / Transparent | Stiff | Low | ~80 °C | Lenses, light pipes, fluidic manifolds, demo parts that show their inside |
Typical layer height50 µm — our everyday setting. 25 µm where detail is critical; 100 µm for speed on large simple parts.
Dimensional tolerance±0.1 mm, or ±0.1 % of the nominal dimension, whichever is greater
Minimum feature size0.2 mm
Minimum wall thickness0.4 mm — 0.6 mm recommended for anything functional
Surface roughnessRa 0.8 – 1.6 µm after sanding — visibly smoother than any other process we run
SupportsAlways required, and removed by hand. Support marks are planned onto non-critical faces.
Post-cureUV chamber at a governed cycle. Required to reach the published mechanical properties.
Heat deflection~80 °C for standard, tough, castable and clear families. High-temperature grades go well beyond that — ask for the figure for the specific grade.
UV stabilityPhotopolymers degrade in sunlight: yellowing and embrittlement over months. A UV-stable clear coat slows it substantially.
AnisotropyReal. A part is weaker across the layer planes than within them, so orientation matters on anything loaded.
ColoursGrey, white, clear, tinted, and painted to a RAL or Pantone reference.
BiocompatibilityFamily-specific. Medical resin is qualified for non-implant models and guides; it is not an implant material.
Food contactNot a default property of any resin we run. Ask before you design around it.
GRADES & VARIANTS
The Six Families in Detail
Each of these is a different chemistry with a different failure mode. Tell us the application and we will pick, rather than defaulting to standard resin.
Tough / ABS-like Resin
FUNCTIONALHigher impact resistance and elongation than standard resin. Suitable for snap-fits, housings and parts that get handled on a desk every day. This is the family to choose when the part has to survive being used.
Impact resistantSnap-fitsHousings
High-Temperature Resin
THERMALRetains stiffness at elevated temperatures — used for mould inserts, hot-air ducting and parts that sit near a heat source. Ask us for the deflection temperature of the specific grade before you design to it.
Heat resistantMould inserts
Biocompatible / Medical Resin
MEDICALFor non-implant applications: anatomical models, surgical guides, drill guides and dental models. We will confirm the exact resin grade and its approval scope on your enquiry rather than implying a general approval.
Anatomical modelsSurgical guides
Castable Resin
JEWELLERYBurns out cleanly in a lost-wax investment casting cycle, so a printed pattern becomes a metal part. The standard route for jewellery and small cast metal components.
Lost-waxJewelleryMasters
Clear / Transparent Resin
OPTICALPolished to optical clarity for lenses, light pipes, fluidic manifolds and demo parts where you need to see the inside. Can be tinted to a colour, frosted or smoked on request.
TransparentLight pipesFluidics
Specialist grades — high-temperature, ESD, rubber-like and filled resins — are available on request. If the part has to meet a specific standard, say so at enquiry stage: qualifying a resin for a regulated application is a different exercise from printing it.
FINISHING
Finishing SLA Resin
Resin is the process where finishing has the largest effect on how the part reads. These are the operations available.
Support removal
Supports are cut away by hand, then the witness marks are sanded flush. Support placement is planned before printing so marks land on non-critical faces.
Sanding & polishing
Progressive grits up to a fine polish. This is what turns a printed part into something that reads as injection-moulded.
UV post-cure
Every part is post-cured in a controlled UV chamber to reach full mechanical properties — skipped post-cure is the most common cause of "my resin part is still soft".
Primer & paint
Grey primer, then colour-matched paint to a RAL or Pantone reference. Matt, satin or gloss topcoat.
Clear coating
UV-stable lacquer that slows the yellowing and embrittlement that sunlight causes in untreated photopolymers.
Tinting & dyeing
Transparent parts tinted to a target colour; clear parts can be smoked or frosted.
Electroplating
A conductive primer plus copper or nickel plating for a genuine metallic finish and EMI shielding.
Assembly & bonding
Multi-part models are pinned and bonded, then seams are filled and refinished so the joint disappears.
WHERE IT FITS
Where Resin Is the Right Answer
Resin wins on detail, surface and transparency. It loses on load, heat and sunlight. These are the applications that sit on the right side of that line.
Strengths
- The highest detail and smoothest surface of any process — layer lines in microns, not tenths of a millimetre
- Sharp fine features: engraved text, thin ribs, small holes down to 0.2 mm
- Transparent, translucent and tinted options that no other process offers
- Class-A appearance straight off the machine with very little finishing work
- A routine dimensional tolerance of ±0.1 mm — the tightest of our four processes as standard
- Excellent master patterns for silicone moulding and investment casting
- Six distinct families, so toughness, heat and clarity can each be specified rather than hoped for
- The cheapest route to a convincing visual prototype
Limits to know
- Photopolymers are not structural — sustained load causes creep even in tough grades
- Supports are always needed, and they leave marks on the surfaces they touch
- Most families soften above roughly 80 °C; only the high-temperature grade goes meaningfully beyond
- Sunlight degrades untreated parts: yellowing and embrittlement over months
- Cost per part rises faster with size than SLS, which makes resin a poor choice for big parts
- Anisotropic: the part is weaker across the layer planes than within them
- Food-contact use needs a specifically qualified material, and should be checked with us first
Form, fit and appearance prototypes
The fastest way to hold your design in your hand and check it against the rest of the assembly, with surface quality good enough to show to a client.
Enclosures and housings
Thin walls, snap-fits, boss threads and crisp cut-outs — printed as one piece rather than assembled from panels. Specify tough resin if the housing will be handled.
Fluidics and micro-channels
Internal channels down to 0.5 mm with transparent resin so you can see flow, and no support material trapped inside.
Dental and anatomical models
Patient-specific models, drill guides and surgical planning aids in medical-grade resin. Non-implant only.
Optical parts and light pipes
Polished clear parts that guide or diffuse light, including tinted lenses for product demonstrations.
Master patterns for casting
Jewellery masters and small-batch metal parts via lost-wax, using castable resin.
High-detail display and collector pieces
Figures, replicas, prop masters and miniatures where surface quality is the entire point.
Silicone mould masters
A single smooth SLA master, moulded in silicone, then cast in resin or polyurethane for a short production run.
COMPARISON
How Resin Compares
Resin is a detail material. Compared against nylon it loses on toughness and temperature, and against metal it loses on everything except appearance and price.
| Material | Process | Density | Strength | Heat | Pick it when |
|---|---|---|---|---|---|
| Ti-6Al-4V | SLM | 4.43 g/cm³ | 900–1100 MPa | ~400 °C | Strength per gram, or biocompatibility |
| 316L stainless | SLM | 7.9 g/cm³ | 480–620 MPa | ~400 °C | Corrosion resistance and ductility |
| AlSi10Mg | SLM | 2.67 g/cm³ | 330–400 MPa | ~170 °C | Light, thermally conductive, machinable |
| Copper & Cu alloys | SLM | 8.9 g/cm³ | 210–400 MPa | ~200 °C | Electrical or thermal conductivity |
| PA12 nylon | SLS | 1.01 g/cm³ | 48–50 MPa | ~120 °C | Tough, complex geometry, no supports |
| Photopolymer resins | SLA | ~1.1–1.2 g/cm³ | 40–70 MPa | ~80 °C | Detail, surface, transparency — not load |
The honest summary: choose resin when the part has to look right or be seen through, and choose SLS nylon the moment it has to work. If a part needs both, it is usually two parts — a resin outer shell and a nylon or metal structure — and we will quote it that way.
FAQ
SLA resin — Common Questions
My resin part feels soft. Why?
Almost always post-cure. A freshly printed part is only partially cross-linked and will not reach its published strength until it has been through a controlled UV cycle. Every part we ship is post-cured under a governed process. If a part arrives feeling soft, or if you are printing in-house and skipping the cure, that is the first thing to check.
How small a detail can you print in SLA?
On a good day, 0.2 mm features survive. Practically, design for 0.4 mm minimum wall thickness and 0.5 mm minimum hole diameter and we will get it out. Anything finer is worth sending the file to check first rather than designing to a hope.
Will my part be strong enough to use?
For a prototype or a display part, yes. For something that carries sustained load, sees heat, or is used outdoors for months, no — photopolymer is the wrong material, and switching to tough resin only moves the limit rather than removing it. Tell us the application and we will point you at SLS nylon or SLM metal instead.
Do supports leave marks?
They can. We plan support placement so contact points land on non-critical faces, and we sand the marks flush. On a visible face we can usually hide them behind a feature. If every face is visible, say so and we will plan the orientation around it.
Can I get a transparent part?
Yes — print in clear resin, then polish to optical clarity. Thin parts come out clearer than thick ones, and we can tint the resin if you need a colour. Note that untreated clear resin yellows in sunlight; a UV-stable clear coat is worth specifying for anything that lives outdoors or in a window.
How do you price SLA parts?
By part volume, machine time, material and finishing — not by bounding box, which is why a hollowed part is much cheaper than a solid one. Our instant quote gives an indicative number in seconds; the final price is confirmed after a file review, which is also when we will tell you if a different resin family would serve you better.
GET STARTED
Tell Us the Application, Not the Resin
Send the part and what it has to do — carry load, take heat, be seen through, burn out cleanly. We will pick the resin family, say plainly where it will fail, and quote the alternatives so you can see what each choice costs.
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