The Framers Forum

Hi,

I'm having some issues when Dry Mounting that I hoping someone can help with?

I am relatively new to Dry Mounting so not too savvy with the tips and tricks...

I have found that when Dry Mounting a heavy height paper (circa 300gsm) to 3mm foamboard (Wessex own stock) that one corner of the paper hadn't stuck. This a test piece, thankfully.

Similarly when attempting to make some spacers using Larson Minuet (AM8627) onto the same 3mm foambaord i had problems, in this case the mountcard came right away hardly sticking at all.

I am using SeaLion H8 Pro DMT tissue, supplied by Lion (4973a) and set my machine to the temp settings suggested (84c) and set the pump for 3.5 mins. In the case of the Mountcard item (for the spacers) I tried on a slightly lower temp (82-3c) and less time at 3mins incase I over cooked it and reduced the effectiveness of the bonding tissue, still the same results.

I also ensure the surfaces where dust free.

I was more surprised that the bonding tissue had adhered to the foamboard but not to the mountcard (at all) and the corner of the heavy weight paper?

What am I doing wrong?

Please can I ask for some guidance?

Many thanks

I have only used Hotpress tissue, but I suspect the only differences would be the required temp and possibly the time.
Have you got sufficient vacuum? I have been told by Steve Goodall of Wessex/Hotpress(their trainer) that you can't overcook tissues by leaving it in too long. The tissue should be bigger than the paper and the foamboard bigger than the tissue and then cut down to the work size after dry mounting. If you are floating you can use a bevelled piece of foamboard smaller than the work but you will have to support the work/foamboard with bevelled foamboard pieces around the sides. I have cut a window in a piece of foamboard, using the fall out as my floating foam piece and then simply added the outside to support it. Always remember that foamboard will often get squashed on the edges by the vacuum, thats why you need the foamboard to be bigger so that you can cut it down and lose the squashed edges...does that make any sense??
If in doubt give Steve Goodall a ring at Wessex Oldham branch, he is the man when it comes to Hotpress vacuum and Drytac roller mounting. I have him on speed dial!!

It's not just temperature a time, also smoothness of surfaces to be joined. If any lack of smoothness creates any areas of less than perfect contact, which are less than the thickness which the dry mounting tissue or film will fill then the applied heat will not be able to cross the gap and cause a satisfactory bond. If you are using a vacuum press, then sucking all the air out may not be uniform across the whole area of the press and this is not always a simple matter to solve. Myself, I use a screw down mechanical press and know how to solve most problems with that, a vacuum press problems are outside of my expirience, so for one of those you need to talk to someone else.

Have you got a sheet of foam on top of the rubber membrane in the press? if not this could be your problem.

There is a drymount adhesive coated board called easymount. I buy any keep in stock a budget version of this board from Simons. It is not expensive to use and saves a lot of time when dry mounting. Many dry mounting jobs do not need to be undertaken with the most expensive materials and in such cases this budget type of board produces a satisfactory result. There is also another grade of dry mount coated board, which uses higher grade materials and I have used this as well, with excellent results. I have never had any kind of failure, when dry mounting using pre-coated dry mounting boards.

Thanks for the advice all.

justin, I spoke to Steve and it’s possible (as I have mounted the items as per the advice you have all kindly offered) that the tissue itself could be the fail point. I will be switching to Hotpress tissues.

Thanks again all, enjoy the sunshine!