retain original collection object even after the collection was filtered

hello,

i am currently trying to improve my store’s filter feature. and one thing that has been bugging me is that once a collection is filtered, and the collection-template is rendered again, then the collection object only holds the filtered products. which prevents me from adding filters to this list.

so for example, if wanted to get all products of size 10, i would apply this filter and the page would reload with the new collection. now i would like to also include products that are of size 11. now that would be impossible since the current collection object has been updated with only the filtered objects of size 10.

so basically what i want is a way to reference the original collection object which contained all the products unfiltered.

Thank you!