Our products have a long shelf life and they are quite expensive so we don't take the risk to eventually damage the foil lid during the process. If you pay attention to the process, the jars are heated (practically boiled) after the lid is applied.
Is the foil suitable for glass jars? If so, can it be heated together with full jars without coming off?
If you could tell me more, C X, I'll be gratefull.
Cătălina
Glass and maybe tin are two of the most difficult container materials for heat-sealing to.
There are heat seal aluminium foil lidding materials that are specially developed for sealing to glass, but even so you cannot say for definite how well it will seal to your particular glass jar. It depends if the glass is coated or at microscopic levels whether it is absolutely smooth or a little rough. I actually know a company that had to rub the glass jar seal area with sandpaper to create a good seal of lid to jar, without the sanding the lids simply fell off.
Once you have a good seal then there is the issue of whether the sealed glass jar will withstand your heat process. They can do no problem, but to glass? Also is your product aggressive (say acidic) that would attack the heat seal lacquer or film? Another variable is the lids can be flat or recessed, so that is another choice to make? With anything like this a lid supplier will supply you sample lids based on their experience and knowledge of your product and process (it is a good idea for you to send them jars to test), but eventually it would be up to you to validate through production and shelf life trials.
I have some experience and contacts in this area, if you want to go down this route. If so send me a PM and I can give you a contact where you can send some sample jars and get sample lids.
One other thing to mention is that you would need to have heat seal machinery in place, but again I have contacts.
Regards,
Simon
