Hot Press Bendy Board

[DEEPJOY]

What am I doing wrong?

Poster bonded to a the white shiny board supplied by Hot Press, baked in the hot press to the correct time. Laid on the bench to cool. Applied a matt laminate over the top, again the correct time and temperature.

When I tried to frame the poster it had taken on quite a curve and the only way I got it to sit flat, was to bond it with double sided adhesive to 2mm MDF before tab gunning it into place.

Do you think the white mount board had taken on moisture and if so, do you recommend a pre bake of the board to reduce the moisture?

Regards
deepjoy

[prospero]

It's a good idea to keep big boards weighted down as they cool. If I'm only doing one I generally switch the press off and leave it for an hour or two before taking it out.

[Trinity]

My own bendy board was ( I believe) caused by me laying it on a hard cold surface in a very warm (fan heater) room. I've done others since and kept everything cool and haven't had the same problem.

[Steve N]

As Prosperp says It's a good idea to keep big boards weighted down as they cool, because you have in total four different materials and they all cool at a different rate, that is what is causing the bending

[stcstc]

the issue is mainly to do with film & laminate contracting on one side at a diff rate the the board. if you for example were to laminate the back of the board too, the tension would be equalized.I know ifs not very practical, but it would solve the issue

[DEEPJOY]

Thank you all, but still a wee bit unclear.

1/The dry mount picture to the board - bake in press.
2/ Take out apply weight and cool.
3/ Put back in press and bake the laminate on.
4/ Take out apply weight and cool.

How long would you leave it weighed down in reference to No. 2 above?
How long would you leave it weighed down in reference to No. 4 above?

[Steve N]

I don't have a Hot Press at the moment, but where I worked before starting my own business, I used to do it all in one go, bond and laminate, take out and put a weight on to cool, job done

[Sam Cook]

Hi

I am adding in a bit late on this one, but can I ask is there a reason why you don't mount and laminate in the same process?

You can basically layer all the work together ie starting from the bottom you have board - adhesive - artwork - laminate. You just need to make sure the laminate is larger (ie overhangs the artwork) by more than the adhesive then you can do everything in 1 go.

Regarding the bending I would say the best options are as already recommended either switch the press off when you are done and leave the work in until everything is cool, or if you want to use the press again then take the work out and lay it on a bench with a weight on it until it is cool, usually 5-10 mintes is enough.

[Graysalchemy]

the issue is mainly to do with film & laminate contracting on one side at a diff rate the the board. if you for example were to laminate the back of the board too, the tension would be equalized.I know ifs not very practical, but it would solve the issue

My dad used to say this was exactly the same problem they had with laminate chip board back in the 70's

Even 18mm MDF will bend to a certain degree so you have no chance with a 1400m backing board.

[DEEPJOY]

Hi

I am adding in a bit late on this one, but can I ask is there a reason why you don't mount and laminate in the same process?

I will in future try the total sandwich approach and layer it all up together. Is it a case of adding the the 2 timings together and punch in that time?

Still a Hot Press virgin! (That's using the machine and not performing on it)

Deepjoy

[Sam Cook]

Yes, I definately recommend it (the sandwich thing that is!).

Typically the laminating takes longer than the mounting so it only needs to go in for long enough to do the laminating and the mounting part will be done perfectly at the same time. Simple!