Do you want to smooth silicone joints or replace your old joints? Perfect! In our training video, we show you step-by-step how to smooth silicone joints and provide practical tips and tricks as well as explain important basics. Enjoy watching!
Create the perfect joint in six simple steps.
Removing the old sealant, made easy. You will need the following tools:
The most important thing when removing the sealant is using a sharp blade. That is why it is recommended to change the cutter knife’s blade before starting to work and to regularly stop work to replace it.
The correct position of the blade allows for a precise and gentle guidance, preventing uncontrolled penetration into the joint that is too deep and damaging the composite sealing underneath.
Pressing the blade with your fingers gently removes the residual sealant from the substrate.
Use caution with composite sealing: In bathroom areas, make sure that the underlying sealing is not damaged.
Loose residual sealant or back-up foam rod must be removed with a brush, hex wrench and/or vacuum cleaner to obtain the optimal substrate for the new joint.
The back-up foam rod not only offers the right retention for the sealant so that it is not pressed into the void, but this also helps avoid a three-edge bond.
Determine the size and select the back-up foam rod
The back-up foam rod should be approximately 20%- 30% larger than the joint width (DIN 18540). In bathroom areas, only use closed-cell back-up foam rods made from polyethylene (PE), since this material does not absorb any moisture.
Introduce the back-up foam rod
It must be introduced into the joint without being physically damaged so that no bubbles form in the sealant (as a result of outgassing of the damaged back-up foam rod). If there is not enough space for a back-up foam rod, use a PE film in line with DIN 18540.
The joint flanks must be load-bearing on their own as well as:
If the joint was wet cleaned, it must be dried or you need to wait until the joint has dried out. Otherwise moisture can infiltrate and adhesion may be impaired.
After removing the old material, it is recommended to vacuum-clean the joint.
Apply OTTO Cleaner T to a clean cloth and use it to clean the joints by wiping only in one direction towards you using pressure (do not wipe back and forth. This does not clean it, but only spreads it around).
With our new guide "Sealing joints in sanitary areas perfectly", you too can become a joint professional.
The smoothing tool should protrude at least 1 mm beyond the edge of the joint to ensure the flank adhesion of the sealant.
Concave shape
PU, silicone and hybrid sealants have approximately 3 – 5% shrinkage. The smoothing tool is curved inward slightly to compensate for this (concave).
No 90° angle
Most smoothing tools do not have a 90° angle, but rather are 87° – 89°. That is why the smoothing tool must be slightly angled to achieve a perfect result.
Free of impurities
Cured sealant residue on the smoothing tool causes unsightly grooves on the surface of the sealant, which at the same time promote the depositing of organic material and thus the formation of mould.
It is necessary to cut the nozzle in order to apply the correct amount of sealant. The inner diameter of the nozzle should approximately correspond to the flank length of the smoothing tool.
Measure the required length and mark it with a waterproof pen.
Ideally, cut the nozzle off at the marked position using a cartridge cutter. This automatically creates the correct angle. Take the nozzle cutter in your left hand, because only one side of the cartridge cutter is angled.
The highest point of the nozzle is marked in order to reach a symmetrical application of sealant later on.
Professional tip: The line at the highest point on the nozzle helps you to correctly align the nozzle to achieve a symmetrical application of sealant.
The sealant is level with the back edge of the nozzle. This means the joint is completely filled.
Too little vs. too much sealant
You can use the slider further below to see exactly what it looks like when there is too little or too much sealant in the joint.
Not enough sealant
The joint is not completely filled.
The sealant does not optimally adhere at the flanks.
Too much sealant
The sealant swells out before and after the nozzle and then smears on the substrate when smoothed off.
The wrong position
There is a gap between the wall/floor and the smoothing tool.
The correct position
Horizontal and vertical angle: There is no gap visible between the wall/floor and the smoothing tool.
To create a perfect corner, the corner should be formed in the sequence and shape as shown in the image on the left.
The design and sealing of a joint is illustrated in our guide.
Find the right sealants quickly and easily with our product filter. Set a check mark under “Standards and tests” characteristics for the desired regulations and you will be shown only the products that match.
When choosing the correct sealant, keep the influences and/or loads in mind as well as the currently applicable regulations.
Take the following influences into consideration:
If you have already found a suitable sealant, it is worth taking a look at the technical data sheet (under standards and tests) to match the requirements with the sealant properties.
Use our application assistant to easily find the right sealant for your project.
In the case of a new building or renovation, the structural joint must be taken into account in the planning or, in the case of an existing structural joint to be renovated, assessed before the sealant is applied. The currently applicable regulations and standards must be taken into account.
The most important points are
Is the component joint correctly dimensioned and therefore suitable for professional installation.
Is the substrate or the contact material suitable in terms of adhesive properties and compatibility with the selected sealant?
Have the external influences, substrate pre-treatment and required tests been taken into account when planning and selecting the right sealant and primer?
The mould infestation of a joint is a very serious and complex issue, because under certain circumstances it can also lead to health impairments. Refer to our guidebook to find extensive information and how you can prevent mould.
The perfect restraint
The right dimensioning
The optimal ratio of joint width to joint depth is an important prerequisite for having the longest possible service life of elastic joint.
Avoid a three-edge bond
You will find extensive information, including charts, in our professional guidebook.
Our application consulting department will be happy to hear from you!
