Professional plasterers agree that joint tape is an important component of a full plasterboard setting system. The tape strengthens and reinforces joints and helps to prevent cracking along the joint lines.
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Plastering tape – three options
Garry McCarron, Siniat’s Technical Field Sales Manager, remembers the early days when cotton joint tape similar to gauze bandage was embedded in the compound to reinforce joins and corners. But we have come a long way since those days and today there are three basic types of joint tape on the market:
Paper tape – by far the product of choice of professional plasterers
“FibaFuse” - the brand name of a paperless joint tape
Fibreglass tape – self-adhesive tape made of fibreglass
What does joint tape do?
Joint tape is essential for the strengthening of joints and to prevent future cracking.
Joint tape supports the joint compound along joint lines and in corners and helps to keep compound in place. Joint lines and corners can be particularly prone to cracking due to the movement of the wall, but the tape helps to keep the compound from cracking and crumbling as the building settles.
Why paper tape?
Most professional plasterers prefer paper tape for its excellent resistance to cracking and provides the strongest possible joint and easily usable with all taping tools.
A good quality paper tape will have the right amount of spark perforations to allow trapped air to escape and avoid bubbles underneath. Plasterers prefer a “crisp” paper with good body, a rough surface for the compound to adhere to and a good crease down the centre for easy folding when applying to corner joints.
It is important to note that there’s a difference between the two sides of the tape. Both sides are buffed to provide better adhesion, but the inside of the roll will always be the smoother side. The outside of the roll should therefore always be applied to the wet compound for the best adhesion.
Paper tape is thin enough (0.2 mm) to create a seamless appearance. Inexperienced plasterers may find self-adhesive fibreglass tape easier to work with, but Siniat recommends using paper tape to create stronger joints that are less prone to defects.
The three-coat jointing system
The three-coat jointing system recommended by Siniat consists of a bedding coat, a second coat and a finish coat of compound. To achieve Level 4 and Level 5 finish, the three-coat jointing system must be used for all joints and external corners. Internal corners only require a bedding coat and a finish coat.
Paper tape is embedded into the compound of the bedding (first) coat. The tape is placed along the joint and bedded into the compound, removing excess compound and any air bubbles from behind the tape.
A skim coat of compound is then applied over the tape.
The second coat of compound is applied after the bedding coat has dried, and the third coat is similarly applied after the second coat has dried. The plasterer will then proceed with sanding the joint to a smooth and even finish.
Contact us to discuss your requirements of drywall joint paper tape manufacturers. Our experienced sales team can help you identify the options that best suit your needs.
Refer to the Siniat Plasterboard Installation Guide for more information about the Three-Coat Jointing System.
Common mistakes
Premature dry-out or tape-lift can occur in extreme conditions, e.g. on hot and windy days. The compound is often blamed, but the truth is that the early exit of moisture due to these conditions can ruin the performance of even the best compounds.
Hot conditions will lead to the compound drying out before the chemical set action has taken place, resulting in the compound becoming soft and powdery and reducing the bond.
When the compound dries noticeably faster than the nominated set time provided on the packaging, change to a compound with a faster setting time.
If the board, especially the ceiling, feels hot to the touch, consider taping in the early part of the day.
Siniat paper tape
Siniat supplies paper tape that has been tested and approved for Siniat systems. It is made from special paper that provides greater tensile strength to prevent tearing, wrinkling or stretching. The paper is machine roughened paper for superior bond generation and a precision-made centre crease allows for easy application. Click here to find out more.
For further information about taping and plasterboard installation, download the Siniat Plasterboard Installation Guide.
Naturally, this means that paper tape also takes a good deal of time to apply, since you have to first do the adhesive layer, embed the tape, wait a few hours for the adhesive layer to dry, and then apply a second coat of mud. This process also takes considerable practice to master and if you aren’t careful to embed the tape perfectly, you’ll end up with air bubbles under the tape that will weaken the joint. That said, a perfectly finished paper tape joint will have less movement – and thus less potential to form cracks – than a mesh tape joint, thanks to that extra mud coupled with the nonelastic nature of paper.
Fiberglass tape, on the other hand, is comparatively easy to work with. It is self-adhesive, so it can be applied to all the joints in one go and then mudded over in a single pass, skipping the first layer of mud entirely. As an added bonus, because it skips the adhesive layer, you don’t need to worry about air bubbles causing problems down the road. All this makes mesh tape easier to work with, especially if you’re not an expert. It can also save you time and is particularly well suited to patch jobs where the strength of the finished joint is slightly less important. The downsides of mesh tape, though, are that it is much more difficult to apply by hand (it can easily get crooked without an applicator and needs a different, special applicator for inside corners) and that you’ll need to finish it with setting-type compound (rather than standard compound), so you’ll need some extra supplies. The setting compound protects against cracks that can develop from mesh tape’s comparatively high elasticity, which can otherwise give joints more movement than they would have with paper tape.
Bottom line: paper tape is a perfectly good choice which leaves a slightly stronger joint thanks to the additional steps it requires, but those extra steps take time, practice, and patience. Mesh tape has a much shallower learning curve and can save you significant time on the job but you’ll need some extra tools and materials to work with it and it can leave a slightly weaker joint even though the material itself is stronger than paper.
If you want to learn more, please visit our website fiberglass mesh tape factories.