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The final step in Insulated Glass Unit (IGU) manufacturing—application of the secondary sealant—is where quality is either sealed in or compromised. Freshly sealed units using silicone or polysulfide require a specific "tack-free" time before they can be handled or shipped. |
When wet IGUs are leaned against each other on a standard A-frame, the weight of the outer units presses against the inner ones. This pressure causes "dishing" or bowing of the glass panes. If the sealant cures while the glass is bowed, the unit is permanently deformed.
This leads to the "Butterfly Effect"—visual distortion that results in customer rejection. By using a slotted harp rack, each IGU stands independently at a 90-degree angle. There is zero cumulative pressure. The sealant cures exactly as applied, maintaining the precise argon gas space thickness required for thermal performance ratings.
Secondary sealants like structural silicone cure by reacting with atmospheric moisture. If units are stacked too tightly, airflow is restricted, leading to uneven curing (soft spots).
Our racks maintain a consistent gap (typically 10-15mm) between each unit. This engineered spacing ensures uniform exposure to air, guaranteeing that your "Work-In-Progress" becomes "Ready-to-Ship" inventory in the shortest possible cycle time.
Consistent spacing allows for optimal airflow, which is critical for the chemical curing process of structural silicones.
Moving wet units from the sealing robot to the curing area is risky. A sudden stop can cause the glass panes to slide relative to each other (subluxation) if the sealant hasn't set.
Our racks feature Non-Slip Base Strips and snug vertical dividers that constrain the glass movement. The unit is held firmly in position, preventing the lites from shifting out of alignment during that critical transport phase across the factory floor.
Yes. Structural glazing often has metal toggles or inserts embedded in the sealant. Our wide-slot options allow space for these protruding mechanical fixings without touching the adjacent glass.
No. The glass only touches the PVC sleeves and the rubber/HDPE base blocks. We ensure that all contact materials are compatible with major sealant brands (Dow, Sika, Tremco) to prevent chemical incompatibility.
Our slotted base design means most drips fall through to the floor. However, the powder-coated steel surface is chemically resistant, allowing dried silicone to be scraped off easily without damaging the rack.
We can manufacture "Robot-Ready" racks with precise locating lugs that allow automated off-loading arms to place wet units directly into the rack slots without human intervention.
Vertical curing is actually preferred for gas-filled units to maintain the seal integrity around the gas fill ports or corner keys. Our racks provide the stability needed to ensure the gas retention barrier forms correctly.
