Industrial Zinc Coffin Soldering

Zinc Coffin Soldering

Q: Which alloy should be used to solder zinc coffin liners?

The industry standard is the 50/50 alloy (Sn50/Pb50) in 41 cm half-moon solder sticks. The 183-215 °C pasty range allows continuous flow and shaping of the bead, an essential characteristic for the perimeter seal on zinc sheet.

Q: Can I use lead-free alloys for zinc coffin liners?

Technically yes, but it is not recommended. Lead-free alloys (SAC305 or 99SnCuNiGe, SN100C equivalent) melt at 217-227 °C, require higher working temperatures and have a minimal or zero pasty range (they are almost eutectic), which makes shaping the bead difficult; they also cost more. For zinc coffin liners, 50/50 remains the traditional choice.

Q: What zinc thickness does DPR 285/1990 require?

Art. 30 of DPR 285/1990 requires the metal casket to have a minimum thickness of 0.660 mm if made of zinc (1.5 mm if of lead) and continuous soldered joints extending around the entire periphery of the contact area of the parts to be joined. For entombment by derogation (art. 106 and Italian Ministry of Health Circular 24/1993, par. 16), 0.74 mm zinc is required.

Q: How much alloy is needed to solder a standard coffin liner?

Approximately 200-400 g of 50/50 alloy for an adult coffin, with a 3-5 mm bead along the entire perimeter of the lid. One 25 kg box covers about 60-120 coffins. For industrial production we recommend orders in pallets of 50-1000 kg with monthly pricing.

Q: Is muriatic acid always needed for pickling?

No. A flux or pickling agent that removes the zinc oxide is needed: the most suitable is a zinc flux based on zinc and ammonium chlorides. Muriatic acid (diluted hydrochloric acid) is also traditionally used; it is more aggressive towards operators and tools and calls for a half mask with an E-P3 filter. In all cases the residues must be removed immediately with a damp cloth. Contact us for the flux best suited to your process.

Q: Is 50/50 RoHS compliant for coffins?

Coffins do not fall within the scope of the RoHS Directive 2011/65/EU, which applies exclusively to electrical and electronic equipment (EEE). The use of leaded 50/50 for coffin soldering is therefore fully legitimate and traditional. For electronic applications, use certified lead-free alloys instead.

Q: Do you provide a chemical analysis certificate for the alloy?

Yes, every lot of Dickmann 50/50 solder sticks is supplied with a complete chemical analysis certificate (spectrometric analysis, spark OES) with lot → customer traceability. ISO 9001:2015. For industrial coffin manufacturers, this makes it possible to accompany every production batch with verifiable quality documentation.

Q: Do you ship throughout Italy? How long does it take?

Yes, we ship within Italy and the EU. Standard lead times: 2-5 working days for 25 kg boxes, 5-10 days for pallets of 50-1000 kg. For continuous supply to funeral homes and coffin manufacturers, we agree a recurring delivery schedule (weekly/monthly).

50/50 tin-lead solder sticks for the hermetic soldering of coffin liners and caskets in zinc sheet

Traditional Sn50Pb50 alloy for hermetic perimeter soldering of zinc coffin liners. Our tin-lead 50/50 solder sticks are the traditional alloy of the funeral industry, for the hermetic closure by soldering required by art. 30 of Italian DPR 285/1990. Certification ISO 9001:2015 certification.

Soldering a seam on zinc sheet with tin-lead solder

Why Choose Dickmann 50/50 for Zinc Coffin Liners

The industry's traditional reference alloy, with certified industrial quality

Continuous Hermetic Closure

With its 183-215 °C pasty range, the 50/50 alloy allows continuous flow along the entire perimeter, reducing voids and leaks, for the hermetic closure required by art. 30 of Italian DPR 285/1990.

Low Working Temperature

Melting between 183 and 215 °C: work at around 250 °C, well below the melting point of zinc (419 °C). Can be worked with a standard gas soldering iron.

Italian Regulatory References

Art. 30 of Italian DPR 285/1990 requires the hermetic closure of the metal casket by soldering; Ministry of Health Circular no. 24 of 24/6/1993 also allows cold sealing. Conformity of the coffin is verified by the local health authority. Chemical analysis certificate for every lot.

Recurring Industrial Supply

25 kg boxes for businesses, pallets of 50-1000 kg for coffin manufacturers. LME-linked pricing, stock confirmation within 24/48 hours, shipping within Italy and the EU.

Soldering Process for Zinc Coffin Liners

Standard operating sequence for hermetic perimeter soldering

Sheet preparation and cleaning

Smooth the edges of the liner and the lid to remove oxides and films. Brush with a wire brush to remove residues. The surface must be smooth and free of impurities.

Flux application

Apply a zinc flux based on zinc and ammonium chlorides to the edges to be soldered; muriatic acid (diluted hydrochloric acid) is also traditionally used. The flux removes the zinc oxide and allows the 50/50 alloy to wet the sheet. PPE: gloves, goggles and a half mask with an E-P3 filter for acid vapours.

Positioning the lid

Place the lid on the liner so that the edge matches evenly. Secure with clips or weights to prevent movement during soldering. Check the flatness of the contact surfaces.

Heating with a gas soldering iron

Heat the sheet at the starting point with a gas soldering iron (LPG, propane or butane) or an electric soldering iron to about 250 °C in the joint area, above the liquidus of the alloy (215 °C). Avoid overheating: zinc sheet melts at 419 °C and burns through easily.

Applying the 50/50 solder stick

Place the half-moon solder stick (flat side down) on the hot spot. The alloy begins to melt progressively. Let it flow evenly along the entire perimeter of the lid, maintaining a continuous 3-5 mm bead.

Shaping the bead

In the pasty range (183-215 °C) the alloy remains workable: with the tip of the soldering iron or a spatula, shape the bead to obtain an even finish and a rounded profile. With eutectic alloys (Sn63Pb37) this step is very difficult.

Cooling and inspection

Allow to cool naturally (do not force-cool with water) and remove the flux residues with a damp cloth. Visually inspect the bead for pinholes, cracks or discontinuities. Check the hermetic seal with a pressure test or continuous visual inspection.

Safety: ensure extraction and ventilation of the workplace; PPE: half mask with E-P3 filter against acid and flux vapours, gloves, goggles. At soldering temperatures lead does not give off significant fumes: the risk is mainly from contact and ingestion, so wash your hands and do not eat in the work area. Italian Legislative Decree 81/2008 sets a limit value of 0.15 mg/m³ for lead and a biological limit value of 60 µg/100 ml; health surveillance is mandatory above the thresholds of Annex XLIII-bis, at intervals set by the occupational physician. Directive (EU) 2024/869 provides for lower values, which apply once transposed into national law.

Dickmann 50/50 Alloy: Specifications for Zinc Coffin Liners

Technical data of the Sn50/Pb50 solder stick in the standard configuration for coffin soldering

Characteristic	Value	Unit	Notes
Composition	Sn 50 / Pb 50	%	Balanced tin-lead
Solidus / Liquidus	183 / 215	°C	32 °C pasty range
Density	8.9	g/cm³	At 20°C
Stick cross-section	10 x 6	mm	Half-moon with '50%' mark
Standard length	410	mm	Sheet-metal work industry standard
Packaging	25	kg/box	Pallets on request
Standard coffin zinc thickness	0.66	mm	Minimum, art. 30 DPR 285/1990
Zinc thickness, derogation	0.74	mm	Entombment by derogation (art. 106 DPR 285/1990, Circular 24/1993)

Application Sectors for Soldering on Zinc

Where 50/50 soldering of zinc coffin liners and metal caskets is used

Funeral Industry

Hermetic closure by soldering of inner zinc caskets, required by art. 30 of Italian DPR 285/1990 for entombment and for the funeral transports covered by the regulation. Continuous perimeter soldering for the tightness of the coffin.

Industrial Packaging

Sealing of galvanised sheet cases and containers for shipping sensitive materials: electronics, precision instruments, museum objects. Leak-tight soldering protects against moisture and water ingress.

Exhumations and Cemetery Articles

Soldering of zinc ossuary boxes and containers for mortal remains. Dedicated supply for funeral homes and stonemasons, with solder sticks in ready-to-use 25 kg boxes.

Special Architectural Sheet-Metal Work

Soldering of complex flashings, zinc gutter fittings, and repair and restoration of zinc roofs. The 50/50 alloy allows fine shaping of the bead on visible joints and curves; for titanium zinc, manufacturers specify 40/60 or 50/50 with low antimony (Sb < 0.5 %).

Hot Soldering vs Cold Sealing

Comparison between the traditional method with 50/50 solder sticks and structural adhesives

Characteristic	50/50 soldering (hot)	Cold sealing (adhesive)	Winner
DPR 285/1990 compliance	Yes (flame soldering, art. 30)	Yes (Ministry of Health Circular no. 24 of 24/6/1993)	Both
Hermetic seal	Excellent — continuous metallurgical joint	Good — depends on the adhesive	50/50 ✅
Working time	20-40 minutes (standard perimeter)	10-20 minutes + curing time	Adhesive
Skill required	Qualified solderer	General labour	Adhesive
Operator safety	Flux or acid fumes, contact with lead — PPE mandatory	Solvent vapours — PPE recommended	Adhesive
Joint mechanical strength	About 35-45 N/mm² (bulk alloy)	Varies by adhesive	Equivalent
Durability	Decades — the metal does not degrade	Variable — some adhesives fail	50/50 ✅
Tradition and acceptance	Historical standard, widely accepted	Permitted since 1993, less widespread	50/50

Hot soldering with 50/50 solder sticks remains the most widespread and accepted standard for coffins. Cold sealing has been a legitimate alternative since 1993 but has not yet replaced traditional soldering.

Frequently Asked Questions on Zinc Coffin Soldering

Everything you need to know before ordering