Heritage Linseed — Technical Specification TFP/THLS/01
Document reference TFP/THLS/01 · Rev A · 02-09-26 · Issued by Tuscan Foundry Products, successor to E.Richards, manufacturers of cast and steel products since 1893.
This is the full technical specification for the Tuscan Heritage Linseed System (THLS), marketed as Heritage Linseed. A plain-language summary is available on that page.
1. Scope
This specification describes the Tuscan Heritage Linseed System (THLS), a traditional linseed oil paint system applied in workshop conditions to new cast iron rainwater goods supplied by Tuscan Foundry Products — gutters, downpipes, hoppers, fittings and associated components.
The system is intended for use on listed buildings, buildings within conservation areas, scheduled monuments, and historic buildings generally, where a historically appropriate, breathable and maintainable finish is required.
Where this specification is referenced in a contract document, the system shall be as described herein without substitution or amendment unless agreed in writing with Tuscan Foundry Products.
2. System description and coat build
THLS is a five-coat system applied to prepared cast iron.
| Coat | Material | Coats | Function |
|---|---|---|---|
| 1–2 | Traditional linseed oil red oxide primer | 2 | Penetrates and bonds into the prepared surface; provides corrosion inhibition |
| 3–5 | Traditional linseed oil topcoat | 3 | Colour, weathering protection and surface finish |
All coats are applied by brush in thin applications. Linseed oil paint must not be applied thickly — excessive film thickness prevents proper oxidation and causes wrinkling, prolonged softness and poor adhesion.
3. Substrate preparation
3.1 Cleaning and keying
Before priming, all surfaces are thoroughly cleaned and mechanically keyed to provide a sound surface for coating adhesion. The preparation process removes any oil, grease, moulding-sand residues, loose scale, rust, surface deposits and any loose or failing existing paint.
Abrasive-disc cleaning is normally used, with blast cleaning where required for intricate profiles, heavily contaminated castings, or previously painted and salvaged items. Once a clean, dry and suitably keyed surface has been achieved, primer is applied as soon as practicable to minimise the risk of flash rusting.
4. Materials
| Paint manufacturer | Brouns & Co. |
|---|---|
| Primer | Traditional boiled linseed oil paint, red oxide |
| Topcoat | Traditional boiled linseed oil paint, colour to selection |
| Standard colour range | 38 colours |
| Custom colours | Available to order; colour matching from samples or historic paint analysis |
| Substitution | No substitution of materials is permitted without the written agreement of Tuscan Foundry Products. Substitution voids the warranty at Clause 15. |
5. Application conditions
| Location | Workshop, under controlled conditions |
|---|---|
| Method | Brush applied |
| Minimum temperature | 10°C |
| Optimum temperature | 15–20°C |
| Air movement | Good circulation required throughout application and cure |
| Film thickness | Thin, even coats. Heavy application is not permitted. |
| Winter working | The system may be applied between October and March. Cure times extend materially at lower temperatures and coats are applied on inspection rather than to a fixed interval. |
6. Cure schedule
Linseed oil paint cures by oxidation, not by solvent evaporation. Each coat must be fully oxidised before the next is applied. Overcoating prematurely causes wrinkling, softening and poor adhesion, and the defect is not always apparent until the system is in service.
| Stage | Favourable conditions (15–20°C) | October – March |
|---|---|---|
| Primer touch-dry | 24–48 hours | Extended — by inspection |
| Interval between coats | Minimum 48 hours; 72 hours preferred | Extended — by inspection |
| Final cure before handling | 7–10 days from final coat | Extended — by inspection |
Coats are applied on inspection of the preceding coat, not to a fixed calendar. Goods are not released before final cure is achieved.
7. Programme and lead time
The cure schedule at Clause 6 has a direct and unavoidable consequence for the construction programme, and it must be allowed for at the point of specification rather than discovered at the point of order.
| Period | Indicative finishing duration from receipt of castings |
|---|---|
| April – September | 3–4 weeks |
| October – March | Materially longer; confirmed at order |
This is a property of the material, not a limitation of service. Any linseed oil paint system correctly applied will require a comparable period. A finishing programme materially shorter than this indicates either thick application, premature overcoating, or a coating that is not traditional linseed oil paint.
Where the construction programme cannot accommodate this period, refer to Clause 13 — Limitations.
8. Colour
- 38 standard colours are available within the range.
- Traditional black remains the most commonly specified finish for cast iron rainwater goods in the United Kingdom.
- Custom colours can be matched from a supplied sample, or from historic paint analysis where a building’s original scheme is being reinstated.
- Colour is confirmed by sample prior to production. Slight variation in appearance between batches is inherent to hand-applied traditional paint and is not a defect.
9. Fixings
Fixings shall be zinc-plated or sherardised. Stainless steel fixings shall NOT be used with cast iron. The galvanic potential difference between stainless steel and cast iron in the presence of moisture will accelerate corrosion of the casting at the fixing point. This requirement applies irrespective of the finish system and should be carried into the specification for the installation as well as the goods.
10. Handling, transport and site storage
- Goods are not handled, wrapped or despatched until final cure is achieved (Clause 6).
- The linseed oil film continues to harden for a period of several weeks after despatch. During this period it remains more susceptible to mechanical damage than a fully matured film.
- On site, goods shall be stored off the ground, under cover, and in a ventilated position.
- Painted surfaces shall not be stacked in direct contact with one another.
- Goods shall not be wrapped in impermeable sheeting for extended periods.
- Installation should proceed as soon as practicable after delivery.
11. Site touch-up
Minor mechanical damage arising during installation may be made good on site. Clean the affected area and remove any loose material; abrade lightly to provide a key, feathering into the sound surrounding film; apply matching linseed oil paint in thin coats, observing the intervals at Clause 6. A touch-up kit in the specified colour is supplied with each order.
Damage exposing bare metal requires the full primer build before topcoating. Contact Tuscan Foundry Products for guidance where the affected area is extensive.
12. Inspection and acceptance
| Stage | Criteria |
|---|---|
| After preparation | Clean, dry, mechanically keyed surface throughout. Loose scale, rust, moulding sand, oil, grease and loose or failing paint removed. Any retained transit primer confirmed sound and well adhered. |
| Each coat | Full oxidation of the preceding coat confirmed before overcoating. Even coverage, no runs, sags, misses or wrinkling. |
| Final | Even colour and sheen across the batch. No mechanical damage. Final cure achieved. |
| Acceptance | By visual inspection at despatch. Goods are photographed prior to despatch and the record retained. |
13. Limitations — where this system should not be specified
Traditional linseed oil paint is the historically correct and technically appropriate finish for cast iron rainwater goods in most heritage contexts. It is not appropriate in all circumstances.
| Circumstance | Consideration |
|---|---|
| Severe coastal or marine exposure | Sustained salt loading and high wind-driven moisture place demands on the film that a two-pack polyurethane system may meet more reliably. Coastal is defined for these purposes as within 5km of the coast. Discuss the specific exposure before specifying. |
| Programmes that cannot accommodate the cure period | See Clause 7. Where finishing must be completed in days rather than weeks, this system is not suitable and a factory-applied alternative should be specified. |
| Goods requiring installation immediately on delivery | The film continues to harden after despatch. Where immediate handling and installation is unavoidable, the risk of mechanical damage rises significantly. |
| Previously two-pack or powder-coated substrates | Two-pack polyurethane and powder coatings do not provide a suitable key or a compatible surface for traditional linseed oil paint. Where such a coating is present and cannot be removed, this system should not be specified. |
| Where a high-gloss modern appearance is required | Linseed oil paint cures to a natural satin sheen and develops a patina with age. It does not replicate the appearance of a modern high-gloss coating. |
| Where the maintenance regime will not be adopted | The system is designed to be maintained rather than replaced. Where no maintenance commitment exists, a lower-maintenance alternative may serve the building better. |
Basis of this clause: the limitations above are derived from the technical characteristics of the material and the cure schedule at Clause 6. They are stated as guidance for specifiers and do not record failures in service.
14. Maintenance schedule
Adherence to this schedule is a condition of the warranty at Clause 15.
| Interval | Action |
|---|---|
| Annually | Visual inspection, with particular attention to joints, outlets, and elevations subject to the prevailing weather. Address any mechanical damage promptly. Photograph the condition. |
| Every 2–3 years | Wash down with warm water and a mild detergent. Remove moss, algae and accumulated debris. Do not use abrasive tools, pressure washing or solvent cleaners. |
| Every 5–7 years | Light refresh with boiled linseed oil applied to the sound film to restore colour depth and sheen. No preparation beyond cleaning is required. |
| Every 12–15 years | Recoat with linseed oil topcoat. The existing film is cleaned and recoated directly. Stripping, sanding and full preparation are not required, provided the film remains sound. |
The principal maintenance advantage of the system is at the 12–15 year point. A modern coating at end of life generally requires removal back to the substrate before recoating; a sound linseed film is simply cleaned and overcoated. This difference is the basis of the system’s whole-life cost position.
15. Warranty
15.1 Warranty given
Tuscan Foundry Products warrants the applied THLS film for a period of ten (10) years from the date of despatch against defective materials and defective workmanship in the application of the system.
15.2 Exclusions
- Mechanical damage of any kind, including damage occurring during transport, handling, storage, installation or subsequent works.
- Damage or failure arising from installation not carried out in accordance with this specification, including the use of fixings other than those specified at Clause 9.
- Third-party components, including castings, brackets or fixings not supplied by Tuscan Foundry Products.
- Defects in the substrate, including casting porosity or defects not reasonably apparent at the time of preparation.
- Failure of, or defects in, the factory-applied transit primer retained beneath the system in accordance with Clause 3.2, or in any other coating not applied by Tuscan Foundry Products.
- Overcoating, alteration or repair of the film by others without written agreement.
- Failure to follow the maintenance schedule at Clause 14.
- Exposure conditions materially different from those disclosed at the time of order, including the circumstances described at Clause 13.
- Normal weathering, patination and colour development, which are inherent characteristics of the material and are not defects.
15.3 Conditions
- The warranty is given to the original purchaser and is not transferable without written agreement.
- Maintenance records shall be produced on request in the event of a claim.
- Tuscan Foundry Products shall be afforded reasonable access to inspect before any remedial work is undertaken.
16. Specification clause
The following may be copied directly into a project specification, under the rainwater drainage systems section. The Uniclass classification reference should be confirmed against the project’s classification structure before issue.
RAINWATER GOODS - FINISH
Cast iron rainwater goods to BS 460, finished with the Tuscan Heritage
Linseed System (THLS) in accordance with specification TFP/THLS/01,
applied in workshop by Tuscan Foundry Products.
PREPARATION Surfaces cleaned and mechanically keyed by abrasive
disc, with blast cleaning where required. Oil, grease,
moulding sand, loose scale, rust and loose or failing
paint removed. Sound factory transit primer retained
and keyed; unsound primer removed back to clean metal.
PRIMER Two coats traditional linseed oil red oxide primer,
brush applied to the prepared surface.
FINISH Three coats traditional linseed oil paint, brush
applied. Colour: ..............................
CURE Minimum 7 days from final coat before handling or
despatch. Extended cure October to March.
FIXINGS Zinc-plated or sherardised. Stainless steel fixings
are not permitted in contact with cast iron.
PROGRAMME Allow 3-4 weeks for finishing and cure, April to
September. Confirm allowance for October to March.
MAINTENANCE To the schedule at Clause 14 of TFP/THLS/01.
WARRANTY 10 years on the applied film, subject to the
exclusions and conditions at Clause 15 of TFP/THLS/01.
17. Document control
| Revision | Date | Author | Change |
|---|---|---|---|
| Rev A | 02-09-26 | Paul Stenning, Tuscan Foundry Products | First issue |
Enquiries regarding this specification: Technical Sales, Tuscan Foundry Products. T: 0333 987 4452