17th century doors in their simplest form were usually made up of vertical planks on horizontal battens or ledges (never ledged & braced in a Z pattern as later 20th century doors) nailed together with the nail ends cleated over.
Many counties having their own distinct style.The boards or planks may be simply butt jointed,rebated or have loose tongues.Often the board edges being beaded to flaunt the joint.
Generally the wider the plank the earlier the door,usually three or four on a normal width door (typically 32-33" x 68-72").
Material by this time would be pine,with a very low percentage being oak,certainly in the more basic house.Oak would have been used in preference though for the front door, and often of double thickness with horizontal boarding on the inside to prevent draughts as well as giving extra strength.
Panelled doors were to be found only in grander properties,often being false panels applied to the boards.
Original doors of this period are,for obvious reasons hard to find, particulary made of oak.

By the Georgian period panelled doors were far more in use with the plank door relegated to cottages and outbuildings.
Much favoured was the six panel door,often with raised and fielded panels and mouldings worked into the stiles and rails.
Again pine was the most common material, but not as we know it today.Georgian doors are generally knot free and have fine,good straight grain.Four panel doors used in lesser houses and non-important rooms of the grander house (typical sizes 32-33" x 72-76" x 1.1/8" - 1.1/4").

Victorian doors, which certainly by the building boom in the latter part,were beginning to be mass produced and imported, being made to standard sizes.
Internal doors in the average house were four panel,although five and six panel doors were used in more expensive properties.
Basic doors were simply square edged on the panels,with loose mouldings applied depending on the rooms importance i.e hall to living rooms moulded both sides,landing to bedrooms moulded on outside only,pantry doors etc. no moulding.In other words one basic item with optional extras which made mass production easy.
The demand being greater, far more fast grown pine was used,which shows in knots and coarser grain.
These doors were made to be painted,often in finer houses they would be grained to resemble a more expensive wood such as oak or walnut.
Typical sizes: standard 30" x 78" x 1.3/8", large 32" x 80" x 1.1/2".
Front doors really blossomed in design during the Victorian period.From the basic solid four panel door of the terraced street to many different styles using stained glass panels,these not only provided light into gloomy hallways but seriously impressed.

As we come into the 20th century things tend to get plainer,simpler and more functional.Was this by demand or as now,was it lead by manufacturers and "time is money" considerations - - - - I wonder?
Increasingly doors are made of imported timber such as douglas fir or canadian redwood with plywood panels.

Almost without exception all pine doors were made to be painted.If you're considering buying painted doors with the intention of stripping them,beware of what stripping may reveal such as: filler,non matching pieces let in,panels varying in colour and worst of all,a door thats been previously stripped using a blowlamp leaving scorch marks which never will sand out!
If you're happy to go ahead next choose the stripping method carefully.Doing it yourself with paint stripper,its time consuming,messy and quite expensive.You could and probally will,regret starting! If you must, then before applying and wasting a lot of stripper,try scraping off the excess where practical i.e. on flat sufaces (an old piece of glass is an ideal scraper).

Professional strippers use three basic methods: Chemical (kinder to the wood and joints but more expensive).
Hot caustic dipping which is my preferred method (but only with an experienced operator) and involves the door being immersed for the shortest time,generally very effective.
Cold caustic,the problem with this is the door is immersed,often for hours,this will have an adverse effect on wood and joints.
Whichever caustic method make sure the door is adequately washed off under pressure.Get it home and let it dry thoroughly,then if any salts form neutralise them by applying ordinary vinegar.

Much of the above goes for buying doors already stripped.Primarily with these or any door check for warping by sighting along the edges and from side to side.Minor warping can be dealt with but if its excessive - - - forget it.

Before going along to buy get your sizes right! Ideally measure the frame and allow for clearance,not forgetting carpets.If doing a new build or making new openings,get your doors first,why? Well there is no such thing as a standard size reclaimed door,most will have been trimmed or adapted over the years and you can make the frame to fit the door.
Prefably buy oversize if possible to allow for some trimming.Weigh up the doors proportions to see whats possible,will it stand an inch off the sides or top and bottom and still look right?

Finally having gone to all this trouble please don't spoil it by fitting incorrect door furniture instead pay us a visit!

Dave Thompson
The Victorian Ironmonger