Project Overview
Key project details for prospective engineering and manufacturing partners
| Product | PURALUM Dual Crystal Applicator |
| Category | Personal care — deodorant applicator |
| Brand | PURALUM |
| Founder | Pre-launch startup |
| Primary market | USA, Australia |
| Secondary markets | UK, European Union |
| Target launch | TBD — dependent on prototype validation gates |
| Development stage | Concept approved — engineering pending |
| Seeking | Engineering partner + contract manufacturer |
| NDA | Please treat as confidential |
Product Description
Dual-surface potassium alum personal care applicator. One product serves two uses: Side A (flat oval crystal surface) for face application; Side B (convex oval crystal surface) for underarm application. Refillable crystal modules. Natural/mineral positioning — 100% potassium alum, no additives (formulation subject to crystal manufacturing method selected — see Crystal Manufacturing section).
Component List (Bill of Materials)
11 components — all concept stage unless noted otherwise
| # | Component | Proposed Material | Method | Est. Weight | Status | Engineering Notes |
|---|---|---|---|---|---|---|
| 1 | Side A Ventilated Cap | PP or ABS | Injection moulding | ~5 g | Concept | Forest green (#1B3A2D), ◯ symbol, ventilation holes in crown |
| 2 | Side A Crystal Module | Potassium alum | TBD — see Crystal Methods | ~18 g | Unconfirmed | Flat oval surface ~28×22 mm |
| 3 | Side A Crystal Support Cup | PP | Injection moulding | ~4 g | Concept | Must include drainage channels |
| 4 | Upper Seal Ring | Food-grade silicone | Moulded | ~1 g | Untested | Prevents water reaching central core |
| 5 | Central Structural Core | PP homopolymer | Injection moulding | ~12 g | Concept | Rigid spine — no water pathway through centre |
| 6 | Silicone Over-mould Grip | LSR Silicone | Over-moulded onto core | ~15 g | Concept | Warm ivory (#F5EDD8), soft-touch matte |
| 7 | Lower Seal Ring | Food-grade silicone | Moulded | ~1 g | Untested | Prevents water reaching central core |
| 8 | Locking Ring / Mechanism | PP | Injection moulding | ~3 g | Under evaluation | Quarter-turn or alternative — see Concepts section |
| 9 | Side B Crystal Support Cup | PP | Injection moulding | ~4 g | Concept | Convex seat, drainage channels |
| 10 | Side B Crystal Module | Potassium alum | TBD | ~18 g | Unconfirmed | Convex oval surface ~30×24 mm, ~8 mm crown height |
| 11 | Side B Ventilated Cap | PP or ABS | Injection moulding | ~5 g | Concept | Sage green (#5C8A70), △ symbol, ventilation holes in crown |
Provisional Dimensions
All values are estimates for concept discussion — not engineering specifications
| Measurement | Provisional Value | Notes |
|---|---|---|
| Total height | ~115 mm | Including both caps fitted |
| Maximum diameter (cap zone) | ~42 mm | At cap flange |
| Grip diameter | ~35 mm | Central grip zone |
| Side A crystal contact | ~28 × 22 mm | Flat oval face |
| Side B crystal contact | ~30 × 24 mm | Convex oval face |
| Side A crystal depth (in cup) | ~25 mm | Crystal height seated in cup |
| Side B crystal depth (in cup) | ~25 mm | Crystal height seated in cup |
| Cap depth (each) | ~18 mm | Including engagement lip |
| Grip zone length | ~55 mm | Central silicone zone |
| Estimated total weight | ~80 g | All components assembled |
| Estimated refill weight | ~40 g | Both crystal modules |
📐 All dimensions are provisional estimates for concept discussion only. Final dimensions must be established via CAD modelling, ergonomic testing, and manufacturing feasibility review.
Engineering Concept Options
Three architectures under evaluation — no final concept selected
Single Double-Ended Cartridge
One internal cartridge holds both crystal surfaces. Quarter-turn releases cartridge from central housing. Founder's current preference for simplicity of purchase and use.
Pros: One refill SKU, minimal components, simple user action.
Risks: Complex sealing at cartridge join, both crystals replaced even if only one depleted.
Is a quarter-turn single-cartridge system achievable at target COGS? What sealing approach do you recommend?
Two Independent Modules
Side A and Side B crystal modules replace independently. Each end has its own locking mechanism and module.
Pros: Maximum hygiene separation, replace only depleted end, easier repair.
Risks: Higher component count, two refill SKUs, more tooling.
Can two independent module systems be manufactured with consistent tolerances? What MOQ applies to each module separately?
Rotating Protective Housing
Outer housing rotates to expose the active crystal surface and protect the other. No separate caps required.
Pros: No loose caps, crystals always protected during storage.
Risks: Complex mechanism, highest tooling cost, sealing the rotation joint with water exposure is challenging.
Is a rotating protective housing mechanism feasible at MOQ 500–1,000? What tooling investment would this require?
Crystal Manufacturing Options & Questions
Four methods under consideration — please provide your capability assessment
Method 1 — Grown Potassium Alum Crystal
Naturally grown crystal, post-growth machining to achieve required shape if needed.
- Can you source or grow cosmetic-grade potassium alum crystals to a consistent shape?
- What shape tolerance is achievable?
- What is the minimum batch size for grown crystals?
- Can flat and convex oval surfaces be produced consistently?
Method 2 — CNC-Cut Solid Alum Block
Dense potassium alum block CNC-machined and polished to final shape.
- Do you have CNC machining capability for mineral blocks?
- What surface finish is achievable? Can you reach <5 μm Ra?
- What is the minimum batch size for CNC-cut components?
- What is the estimated unit cost at 1,000 pieces?
Method 3 — Compressed Alum Composite
Ground potassium alum compressed into shape using compression moulding.
- Is binder-free potassium alum compression commercially viable?
- If binders are required, what binders are typically used and in what proportion?
- What is the dissolution behaviour of compressed vs grown crystal?
Method 4 — Crystal in Polymer Carrier
Exposed crystal insert seated and retained in a precision-moulded polymer carrier.
- Can potassium alum inserts be reliably bonded or seated in a PP carrier?
- What is the failure mode at the crystal/polymer interface when wet?
- What is the estimated unit cost for carrier + crystal at 1,000 pieces?
Material Preferences
Preferred materials for each component — manufacturer substitutions welcome with justification
Silicone Over-mould Grip
- Grade
- Food-grade LSR
- Colour
- Warm ivory #F5EDD8
- Finish
- Matte soft-touch
- Requirement
- Must not discolour with water
Central Core
- Grade
- PP homopolymer
- Colour
- Off-white (hidden)
- Finish
- Not critical (internal)
- Requirement
- Rigid — no flex under grip pressure
Potassium Alum Crystal
- Grade
- Cosmetic / food grade
- Colour
- Translucent milky white
- Method
- TBD — see Crystal Methods
- Requirement
- Consistent shape, no additives preferred
Caps (A & B)
- Grade
- PP or ABS
- Side A
- Forest green #1B3A2D
- Side B
- Sage green #5C8A70
- Finish
- Matte semi-gloss
Seal Rings
- Grade
- Food-grade silicone
- Colour
- Natural / clear
- Finish
- Smooth
- Requirement
- Resist continuous wet/dry cycling
Ventilation
- Approach
- Integrated into cap moulding
- Not
- A separate component
- Pattern
- Ring of small holes in cap crown
- Requirement
- Allow airflow, exclude insects
Manufacturer substitutions welcome if equivalent or superior performance can be demonstrated. Please note any restrictions or concerns with proposed materials in the response form.
MOQ / COGS / Tooling Targets
Founder targets shown — please complete the Manufacturer Quote column
| Item | Founder Target | Manufacturer Quote |
|---|---|---|
| MOQ — first production run | 500–1,000 units | To be provided |
| Target COGS per unit (all-in) | USD $6–9 | To be provided |
| Total tooling cost (all moulds) | < USD $15,000 | To be provided |
| P4 sample cost | < USD $2,000 | To be provided |
| Sample lead time | 6–8 weeks | To be provided |
| Production lead time | 8–10 weeks | To be provided |
| Packaging (retail box, included) | Included in COGS target | To be provided |
Testing Requirements
Please indicate which tests you can support when submitting your response
| Test | Prototype Stage | Pass Criteria | Can You Support? |
|---|---|---|---|
| Grip comfort | P0 | >7/10 user rating | Yes / No / Partial |
| Face contact | P1 | No edge pressure complaints | Yes / No / Partial |
| Underarm contact | P1 | Comfortable coverage reported | Yes / No / Partial |
| Cap retention | P2 | No cap loss after 100 inversions | Yes / No / Partial |
| Cap ventilation | P2 | <20% humidity inside cap after 24 h | Yes / No / Partial |
| Water ingress | P2 | No water in central core after 30 s submersion | Yes / No / Partial |
| Drainage | P2 | Full drainage <60 s | Yes / No / Partial |
| Crystal cracking | P3 | No structural cracks after 100 use cycles | Yes / No / Partial |
| Crystal wear | P3 | <5% mass loss per month (estimated) | Yes / No / Partial |
| Refill removal | P2 | <5 N removal force after 50 cycles | Yes / No / Partial |
| Refill locking | P2 | Positive lock every cycle for 50 cycles | Yes / No / Partial |
| Product stability | P1 | No tipping at 15° on wet tile | Yes / No / Partial |
| Silicone staining | P2 | No discolouration after 30-day water exposure | Yes / No / Partial |
| Heat exposure | P2 | No distortion at 50°C for 24 h | Yes / No / Partial |
| Cold exposure | P2 | No cracking at 0°C for 24 h | Yes / No / Partial |
| Wet/dry cycling | P3 | No seal degradation after 100 cycles | Yes / No / Partial |
| Travel durability | P2 | No internal damage after 500 km vibration test | Yes / No / Partial |
| Packaging transit | P4 | No product damage | Yes / No / Partial |
| Hygiene validation | P3 | Meets cosmetic hygiene guidelines | Yes / No / Partial |
| Customer comprehension | P4 | >90% correct first use without verbal instruction | Yes / No / Partial |
Please mark the "Can you support?" column with Yes / No / Partial when submitting your response via the form below.
Packaging Requirements
Preferred packaging brief — substitutions welcome with justification
Retail Box
- Material: FSC-certified board (kraft or white finish)
- No plastic window — eco positioning
- Proposed size: ~55 × 55 × 130 mm
- Insert: die-cut paper/board, no foam preferred
- Crystal must be protected from impact
- Labelling: front (product), back (ingredients/instructions), side (certifications)
Refill Packaging & Shipping
- Refill box: ~50 × 50 × 60 mm small kraft box
- Must clearly indicate Side A or Side B refill
- Shipping carton: 24 units per carton (provisional)
- Moisture-resistant inner liner preferred
Technical File Package
Pending product engineer engagement — files listed so manufacturers know what documentation to expect
STEP Assembly File
Complete product assembly in STEP format
Pending product engineerComponent STEP Files
One file per component (11 files)
Pending product engineerSTL Appearance Model
Full product appearance model for review
Pending product engineerDimensioned PDF Drawings
Orthographic drawings with all tolerances
Pending product engineerExploded View PDF
Numbered exploded view with BOM reference
Pending product engineerCMF Specification Sheet
Colour, material and finish specification
Pending product engineerBill of Materials (Excel)
Full BOM with part numbers and weights
Pending product engineerPrototype Test Plan
Detailed test plan for P0–P4 stages
Pending product engineerPackaging Dieline
Retail box and refill box dielines
Pending product engineerRFQ Document
Formal request for quotation
Pending product engineerSubmit Your Response
Express interest, answer questions, or ask us anything about the project