Basic Hot Fix Principles
Hotfix elements have a coating of hot-melt glue on the back, enabling swift, simple application. This glue is activated by heat (applied either directly or indirectly via ultrasound), and bonds with the carrier material. When cooling, the glue hardens and securely and permanently fixes the elements in place. The Swarovski Hotfix adhesive is characterized by its wash resistance and easy-care properties. The temperature, application time and pressure can be varied according to the carrier material.
Before beginning the application process, you should always check whether the carrier material is suitable for Hotfix application. Please check the following criteria:
- heat resistance (min. 120°C/250°F)
- resistance against pressure
- application area of the product
- suitability of surface properties and absorbency
Checking absorbency via the water drop test
The water drop test is a quick and easy way to get an initial idea of the absorbency of the carrier material.
Apply a couple of drops of water onto the carrier material. If the material quickly absorbs the drops, it offers good absorbency. If the water pearls off the carrier material, or if it takes a long time to be absorbed, the material offers insufficient absorbency. This can impair the effectiveness of Hotfix application.
Some textiles and special finishes are unsuitable for Hotfix application, due to a lack of absorbency.
This is a list of unsuitable carrier materials and finishes:
- very tightly woven textiles
- very thin fabrics, e.g. organza
- smooth leather and smooth imitation leather (Swarovski application solutions such as Chaton Leather and Flat Back Leather are featured in the “General Information” chapter)
- hydrophobic or water-repellent treatments (silicone, synthetic resin as a waterproofing agent)
- Teflon coatings
- stain-resistant treatments
- easy-to-care treatments
- fluorocarbon finishes
- softening agents
- select dyes (dyes with metal pigments)
- enzymatic treatments
It can sometimes be helpful to wash the carrier material before application, in order to remove any unsuitable finishes (particularly softening agents), and thus improve absorbency.
Generally, the following parameters are most important when carrying out Hotfix applications of Swarovski crystals:
- Application time
- Application side
Swarovski Hotfix adhesive is activated within a temperature range of 120°C to 170°C (250°F to 340°F). A suitable application temperature can be selected from this range according to the carrier material and its sensitivity to heat.
With heat presses, the temperature selected on the display does not always reflect the actual temperature on the surface of the press. Often, the temperature can be distributed unevenly, or one heat plate may be defective.
It is therefore recommended to regularly check the temperature with a laser measuring device or temperature measuring strips at various points on the heating surface, to ensure the temperature is distributed evenly across it.
Checks should be carried out regularly (once per week), particularly during production.
The pressure setting depends on the Hotfix elements to be applied, the carrier material, and the technical equipment (machines, etc.) available.
Too much pressure can cause the adhesive to be spread out and can also affect the surface of the carrier material. Too little pressure, however, can result in a weak and insufficient bond between the crystal and the carrier material.
In general, the pressure should be applied directly to the crystal elements (e.g. Flat Backs Hotfix, Transfers, Crystal Mesh).
It is therefore necessary to check if there are any buttons, zippers or other raised parts surrounding them. Always use a compensating pad to even out the surface.
When applying Swarovski crystals of different heights, a compensating pad should always be used. Silicone foam or foam rubber can be used here.
Take great care to apply pressure evenly when using a heat press with a scissor mechanism. The upper plate of the heat press must be completely horizontal in order to effectively and evenly distribute pressure and temperature.
In general, the application time should be sufficient to allow the hot-melt glue to be fully activated, and then to penetrate the carrier material. The application time necessary depends on the Hotfix elements, the temperature selected, the machine used, the carrier material and the application side.
Hotfix elements can usually be applied from the front and the back. A shorter application time can be achieved with thinner fabrics by applying crystals from the back, as the heat reaches the adhesive through the carrier material faster, activating it immediately.
When applying Hotfix products on thick or multi-layered fabrics (such as seams) the application side selected should be the one that allows the heat to be transferred to the hot-melt adhesive quickest. This ensures fast, optimum activation.
Defining the optimum applicaton parameters
Adhesive has been successfully activated when, using a magnifying glass, it is possible to see a thin edge of glue formed around the crystal. On thin fabrics, the optimum application parameters are chosen when the glue will have lightly penetrated through the fabric and is lightly visible at the reverse.
When parameters have been incorrectly selected, such as an extreme application temperature, pressure, or application time, significant amounts of glue can spread out.
When the application temperature or pressure is too low, or the application time too short, the adhesive cannot be sufficiently activated, leading to problems with adhesion.
Application Using a Heat Press
A heat press is the ideal tool for applying Hotfix products as it can be used to apply even, adjustable pressure. All SWAROVSKI ELEMENTS mentioned in the product overview can be applied using the following steps.
To adjust the application parameters and the aids to achieve an ideal balance, it is strongly recommended that tests are carried out with the original material.
If adhesion is insufficient following the application process, it can be repeated, adjusting the parameters (such as pressure, time and temperature). Please ensure that the application process is repeated from the very beginning, and that the initial application time is combined with the additional time.
For example: After application, it is clear that the application time of 10 seconds was insufficient. Pressure should not just be applied for a further 5 seconds—the process must be repeated in its entirety, with an application time of 15 seconds.
Application using a KANDI Kane
Applicators are a cost-effective way to apply Flat Backs Hotfix (SS 6 to 34) onto the carrier material.
Hot-melt adhesive generally requires 24 hours to cure completely. Any washing or quality assurance should take place after this period.