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Known as Self Seal, Cold Seal or Pressure Seal, you will have experienced this form of sealing most commonly on a self seal envelope.


However, Packaids are one of very few companies that are able to apply this self seal liquid latex to a vast array of blank or pre-printed substrates with a very heavy coverage - and we can even apply it to pre-die cut items (subject to design).


The use and applications for this are vast, diverse and incredibly useful, from purpose made items to being used for speeding up hand finishing projects, all without any need for equipment, glue, tape or mess being incurred in the latter fulfilment finishing process.


The video below will give you a brief insight into how it works with different items (apologies for the quality of presentation - I have a great face for radio and a superb voice for silent films)...

Self-Seal Icon


Amongst Self Seal Latex's various uses are trapped blister cards for packaging. This form of encapsulation has many, many benefits...


  • Reduction of the amount of plastic required (compared to Clam shells)

  • Allows for a highly visabie print area to be used both front and back with clear inspection of the product possible

  • Environmentally friendly (the blister separates from the card with no glue residue left on the blister, which means both elements can be recycled appropriately)

  • High Security

  • Ideal for clients that want packaged items fulfilled on an ad-hoc basis as and when required rather than the investment of a large quantity of stock being produced ready for a large packing run

  • Flanges of the Blister are hidden to give a better presentation (compared to blisters heat sealed on to cards)

  • Huge reductions in costs compared to clamshell packs and heat-seal trapped blister packs

  • Reduced packaging weight

  • Can allow product to protrude from both sides allowing item to be fully inspected as well as hang straight

  • Equivalents require measured Heat, Time and Pressure - With Self Seal only one parameter is required to be controlled - pressure - making it an extremely reliable and stable process.

  • No heat involved alleviates common issues such as print discolouration, curving of the blister card, and deforming of the blister

  • Addition of lamination post print can increase the security even further to being tear resistant

  • Fulfilled aluminium foil lidded blisters can be trapped with perforated reverse openings to gain access to pills etc.

  • If designed well, it can be tamper proof/evident, and yet product removal can be VERY accessible to consumer through clever uses of perforations enabling both product and blister to be removed easily


What's even more incredible, is all of this can be achieved without the fulfiller requiring any additional equipment or tooling whatsoever!


When it comes to longer runs, if compared to heat seal trapped blister packs, again, the savings are enormous and the increase in productivity is huge. Only pressure is required with the self seal blister card, no heat, and therefore only a quarter of the dwell time is also required, allowing for a much faster production process. Self sealing trapped blister cards can be used with existing heat seal trapped blister card machinery by simply switching off the heat and reducing the dwell time to then be running much faster, and at no heating costs (which again is a great benefit to the environmental footprint!).



Other items we commonly produce for clients with self sealing latex applied are...


  • Medical Pill Packs (perfect solution for trial size runs)

  • Reply Mailers (great alternative to licking remoist gum)

  • Front Cover Exam Sheets (for confidentiality)

  • Duplexed & Triplexed Sheets (Click here to see our duplexed business cards)

  • Perfect Peel & Reveals

  • Advent Calendars

  • Envelopes

  • Coin Cards

  • Encapsulation

  • Double Thickness Canadian Bound Covers

  • and so much more



Packaids have five sheet-fed presses running latexed sheets at around 1,500 to 3,000 sheet p/hour depending on the coverage, substrate and sheet size, we can process sizes from A4 to over B1 with up to 95% coverage of the sheet.


Packaids apply liquid latex to a sheet using a hand cut use once stencil through our sheet fed presses, once the liquid latex has been transferred onto the sheet it is cured inline by radio frequency driers.


The latexed sheets are immediately ready for die-cutting or trimming. In both cases, Packaids die-cut and trim latexed sheets on a daily basis, however, if you prefer flat sheets back for doing these processes in-house, it's not a problem, we would be happy to give advice as to how to handle the latexed sheets efficiently.


Self Sealing Latex will only bond to itself i.e. latex to latex and won’t create a bond to an untreated part of the sheet, the only time this is untrue is when great pressure is applied directly onto to a stack, (around 3,000 sheets is usually the most amount of latexed sheets we would ever supply back on one stack, and should never be double stacked).


Items that have not yet been bonded together (i.e. latex to latex) have a shelf life of over six months for this process to be done, once bonded together they should have a fibre tear bond (subject to substrate used) within 24 hours, and shouldn’t ever unbond.


The bonding of latex to latex is ineffective if the room temperature is below 8˚C, but temperature is not a problem if the item has already been bonded before going into such an environment.


An item can be bonded together simply by using firm hand pressure, if there is in excess of 250 items to bond consecutively, we would recommend a small investment in a commonly purchased hand wallpaper roller to alleviate any hand strain and to speed the process up, and if the item has a blister, a quickly routered jig made out of a piece of wood to place the item face down greatly helps too. If the quantities are much larger, there are many purpose made semi and completely automated press machines available.

Latex is a natural product that comes from the Hevea Brasiliensis rubber trees grown on large plantations, it is collected by cutting thin strips of bark from the tree, and allowing the latex to drop into collecting vessels.


In landfill conditions, latex will biodegrade at about the same rate as a leaf from an oak tree. 

Rubber Latex Tree


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