Types Of Joints, Woods, and Finishes

In the carpentry world, there are thousands and thousands of possibilities on how you can do your work. Here are different ways and types on how to joint 2 different planks of wood.

Types Of Joints

Basic Butt Joint

There is no more basic wood joinery than the butt joint. A butt joint is nothing more than when one piece of wood butts into another (most often at a right angle, or square to the other board) and is fastened using mechanical fasteners. This type of joint is often used in wall framing on construction sites.

Mitered Butt Joint

A mitered butt joint is nearly the same as a basic butt joint, except that the two boards are joined at an angle (instead of square to one another). The advantage is that the mitered butt joint will not show any end grain, and as such is a bit more aesthetically pleasing. However, the mitered butt joint isn't all that strong.

Tounge and Groove Joint

When joining two boards square to one another along a long edge, one can simply butt the joint together and hold it with fasteners. However, the tongue and groove joint is much stronger and provides more adjoining surface areas, which is particularly useful if you're going to glue the joint.

Sliding Dovetail

A sliding dovetail is a versatile joint with a lot of possible uses. A good way to think of it is as a locking dado. Learn the keys to building a clean sliding dovetail joint, and when to use one.

Joining woods.

Joining woods by Nails, Glues, Screws, and even Double Sided Tapes!

Types Of Wood

Types Of Finishes

Exterior Finishes

Paint Type	Comments
Conventional opaque systems - water based 100% acrylic	Best suited for use on sawn or textured durable timbers. More frequent but much simpler maintenance. One can expect 3/5 years north face before a further coat is required. More opaque finishes can last longer before recoating is required.
Water Repellent Preservatives	Temporary pre-treatment to prevent soiling and deterioration during construction but have limited life if not over-coated. Only use when you know what you plan to use (compatibility) to complete the painting or staining. Check with the manufacturer.
Wood primers	Brush application is recommended. Solvent borne – better penetration, but slower drying. Water borne - better long term flexibility, quicker over-coating and easier clean up.
Under coats	Good opacity and bridging properties. Increase system film build and durability. Solvent borne - best over chalky surfaces. Water borne - faster drying, better flexibility and easier clean up.
Finishing Coats Gloss	Alkyd or enamel paints not recommended. Water borne has slightly lower initial gloss, better gloss retention, and better film flexibility after aging. Water borne paint systems applied to primed timber using premium 100% acrylic house paint has become the only recommended option for exterior applications
Finishing Coats - Semi-glass	100% acrylic house paints in both semi gloss and low sheen offer very good exterior durability. The lower the gloss the more chalking can occur. Light bright colours chalk less and it’s harder to see.
Finishing Coats: Flat and Low Sheen	Low sheen and flat finishes offer good exterior durability. The darker the colour the more you’re going to see the chalking of the surface. Surface chalking while it does appear as a surface change, under most circumstances does not detract from the protection offered to the substrate by the paint film. If you can’t live with a chalky surface then go for a higher initial gloss level in a bright/light colour.
Natural Finishes	Enhance both timber grain and texture and help maintain timber colour. Check with the manufacturer of your chosen product for application instructions and coverage recommendations. Be prepared to carry out more maintenance, choose areas that are not exposed to direct sunlight.
Finishes Clear	Enhances timber appearance but requires a commitment to more regular maintenance with frequent inspections. The use of clear varnishes has been advanced by UV absorbers. These absorbers however cannot absorb all the UV light, creating problems for the surface of the wood. Delimitation of the film is most often caused by failure of the wood at the coating interface.

Paint Systems

Most pigmented paint systems for both protection and decoration consist of a three-stage process:

• Wood Primers
• Undercoats
• Finishing coats

For exterior applications 100% acrylic paints offer the best long term durability.

Wood primers

These provide good adhesion to the timber and a good foundation for subsequent coats.

They may be solvent borne, comprised of synthetic alkyd resins. Or the more recently developed water borne primers that contain an acrylic emulsion as the principal binder are alternatives that offer good adhesion to timber and greater flexibility, particularly on ageing.

The problem of tannin staining, when applied to timbers containing natural, water soluble tannins, has been largely overcome by use of fixative pigments and special emulsions developed for this purpose. Water borne primers do allow greater water vapour permeability than solvent borne. But in combination with the undercoats and finishing options they provide longer durability than a full enamel/alkyd system that hardens with age.

Wood primers used to be commonly tinted to a pink colour, a fall back to the days when white lead and red lead were mixed together in the paint. Today wood primers are lead free with many now coloured to be associated with a company’s brand.

Coloured primers help with greater apparent opacity and a contrasting colour for the next coat being applied. It avoids areas being missed during application and ensures that a sufficient second primer or undercoat is applied.

Note that timber treated with light organic solvent preservatives (LOSP) [refer AS 1604 – Specification for preservative treatment] may be delivered in a pre-primed condition. Pre-primed timber comes in many options:

• As a brand that can be recognised. Follow the painting recommendations of that brand
• Not identified. Therefore paint as if the primer is only a holding primer i.e. a full coat of premium exterior primer will be required, either alkyd or acrylic before you apply your top coat acrylic.
• Several manufacturers of weatherboard and mouldings have very specific primer applications that require fewer coats as they have already applied the primer and undercoat. Follow their recommendations, chose a premium brand of paint, follow the recommended coverage rates and don’t short cut on the number of coats.

Undercoats

hese are the bridging coats between the primer or previous paint surface and the finishing coat. They have good bridging properties across cracks, good brush-ability under most conditions, facilitate sanding, good gloss hold out which enhances the durability of the total system and have good opacity capable of substantially obscuring the background colour or colours.

Similar to primers, they can be solvent or water borne. Solvent borne undercoats are generally superior for adhesion if applied to slightly chalky or powdery surfaces and are formulated to give superior sanding properties. Acrylic undercoats are more flexible and offer better durability.

Finishing Coats

In all pigmented coating systems, (better known as paints, as distinct from stains), water borne paints have a decided advantage over solvent borne in terms of long term durability, ease of clean up of equipment and faster drying and re-coat times. One restriction, however, is that they must not be applied or allowed to dry at temperatures below 10 degrees Celsius, as film formation may not occur and the paint may become powdery.

Manufacturer’s directions should be followed at all times, particularly with regard to the system or succession of coats to be applied.

Film-forming Finishes

Gloss

These are available in a wide range of colours. The need to provide a wide colour range, while restricting stock items, has led to the use of tinting systems in preference to large numbers of ready mixed colours. Refer to the section on LRV before you chose your colour.

Water borne gloss exterior finishes are now widely used. They have superior chalk resistance; flexibility and gloss retention. They frequently provide a useful film life that is double that of the solvent systems, if they are applied to suitably prepared, primed and undercoated surfaces. When these water borne finishes are used for re-painting it should be remembered that old, embrittled alkyd or oil-based finishes will continue to harden with time and will eventually fail irrespective of the type of re-paint top coat used.

Exterior water borne finishes are generally based on emulsion resins, the most popular and proven type being pure or 100% acrylic emulsions. Don’t assume that because it’s water based it’s 100% acrylic unless it’s stated on the can.

Semi-Gloss/Satin

Satin and semi-gloss finishes, are similar in many respects to their full gloss counterparts but have had the gloss level reduced by the addition of flattening agents.

While quite suitable for exterior use, when recommended by the manufacturer, they tend to chalk earlier but do not highlight minor imperfections in the substrate as readily as gloss finishes. They are frequently available in the same extensive colour range as gloss finishes.

Flat/Matt and Low Sheen

The use of 100% Acrylic emulsions gives very good exterior exposure performance over primed timber substrates where film flexibility on ageing is important.

The term low sheen is generally used to indicate a finish with a slightly higher sheen than either flat or matt. Low sheen finishes mask minor imperfections in the substrate more satisfactorily than gloss or semi-gloss finishes. Low sheen finishes can look very nice when used on rough sawn surfaces.