The Restoration

The process of restoring sash windows is not simple, but the work involved means your windows are fit for at least another one hundred years of wear, tear and whatever the elements throw at them.  Here’s 20 steps which detail how Box Sash Restoration restores your valuable sash windows:

  1. Window sashes are removed and taken to the workshop
  2. Ironmongery is removed and the sashes are stripped to the bare wood
  3. Glass and putty is removed; the glass is put aside for cleaning and re-use where possible
  4. Sashes which are sound are knocked apart, and the joints are then injected with thixotropic boat-builder’s adhesive; the sashes are then squared and clamped
  5. Rotten cills and other parts are then removed and replicated in old pitch pine or Douglas Fir, quarter sawn for stability and strength; when dry, the sashes are then sanded by hand, ensuring that the mouldings are crisper and more sharp than when new
  6. Rotten sash stiles and frames are repaired, using sixty degree, half-lapped scarf joints, which are cut and planed by hand
  7. Meeting rail-lips on the sashes are then replaced to ensure draught-proof closing of the window; this is also done with old-growth lumber; draught seals and meeting rails become dirty and unsightly very quickly – we just don’t use them!
  8. Sashes are then grain-filled, and sanded to ensure completely flat surface for re-decorating
  9. The sashes are then saturated in primer preservative
  10. 24 hours later, the sashes get their first micro-porous undercoat
  11. The window sash is then re-glazed using fresh putty; crown glass or modern glass is used, and cut to fine tolerances to ensure a proper seal
  12. The first undercoat on the window is then de-nibbed, with 240 git paper, and then the second undercoat is applied and cut-in to the back of the glass
  13. Putty bevels are then applied to the outside face of the sash, perfectly straight, allowing one-sixteenth for decorating
  14. When all the sashes are complete, the box frames are restored on site, stripped and preserved
  15. Box frame corners, cills and reveals are also scarf-jointed, and replaced with old pitch pine or Douglas Fir
  16. Primer and two undercoats are then applied to the frames; the sashes are then weighed and hung, using the correct weights and woven nylon sash cord
  17. Sashes are planed to fit properly, and fitted with a friction free parting bead, which also stops draughts; staff beads at the rear of the window are also replaced and waxed to ensure smooth operation
  18. The sashes and frames are then glossed when hung, with micro-porous gloss and solid brass sash fitches, and lifts are fitted; beeswax is then applied to all touching and sliding surfaces, to ensure no sticking
  19. After three-to-four weeks, the properly-cured putty is coated with oil-based undercoat and micro-porous gloss is applied, cut into the sealed glass and putty in the traditional manner
  20. The window is now good for another 100 years-plus, with the correct maintenance; contact Box Sash Restoration to have your windows re-glossed every five years

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