FRP sheets...

[webtrekker]

Ok, the story so far ...

I've tried the following methods (on white, cast acrylic, 3mm thick):

• Pressing at 190 °C for 60 secs and cooling under a weight - Result: Image great, but mild distortion of acrylic.
• As above, but then re-heating to 100 °C in my halogen oven and pressing COLD for 30mins - Result: Same kind of distortion and SHRINKAGE.
• Pressing at 170 °C for 30 secs and cooling under a weight - Result: Image faded around edges, still some distortion.
• Finally, pressing at 190 °C for 60 secs and just allowing to cool naturally on a flat surface - Result: BINGO! Great print, no distortion, no shrinkage!

So it appears that the best method is to let the pressed acrylic settle naturally on a flat surface with no added weights.

Still early days though and still experimenting.

[Leadbelly]

Good man it's great when you achieve something after you have had the bit between your teeth, I commend you for sharing the process and the results. The simple fact that if any of us decided to make something bespoke using the same materials, I'm sure it's down too you that we would now have the confidence.

First class

[pisquee]

Trying to remember back to when we did this ... it could be (can't remember) that the second PressMech wasn't cold, but at a warm temperature the subsequently flatten out the warped printed sheets.

In terms of shrinkage, the project we worked on this wasn't an issue, but we do see this as the norm with textiles printing - the shrinking width and length depends on the weave of the fibres, and can be calculated as a %age ... with fabric you can pre-press it by running through the rotary press by itself, this pre-shrinks it and evaporates off any moisture in the fabric, and helps get it to a good working temp, after sitting in a cold warehouse or delivery van.
To work out %age shrinkage ... we draw out a 50cm or 100cm square, with a marker pen, and then run it through the press at normal speed and temp, and then measure that square afterwards to work out the differences. We do this for each of the different fabrics we use.

In terms of fabrics, yes, we buy by the roll from textile wholesalers, and not sublimation suppliers. Doing this means we don't pay a sublimation tax, but get much higher quality fabrics for the interiors products we make, although we certainly pay more than £1 per metre for the poly canvas we use.

[pisquee]

Trying to remember back to when we did this ... it could be (can't remember) that the second PressMech wasn't cold, but at a warm temperature the subsequently flatten out the warped printed sheets.

In terms of shrinkage, the project we worked on this wasn't an issue, but we do see this as the norm with textiles printing - the shrinking width and length depends on the weave of the fibres, and can be calculated as a %age ... with fabric you can pre-press it by running through the rotary press by itself, this pre-shrinks it and evaporates off any moisture in the fabric, and helps get it to a good working temp, after sitting in a cold warehouse or delivery van.
To work out %age shrinkage ... we draw out a 50cm or 100cm square, with a marker pen, and then run it through the press at normal speed and temp, and then measure that square afterwards to work out the differences. We do this for each of the different fabrics we use.

In terms of fabrics, yes, we buy by the roll from textile wholesalers, and not sublimation suppliers. Doing this means we don't pay a sublimation tax, but get much higher quality fabrics for the interiors products we make, although we certainly pay more than £1 per metre for the poly canvas we use.

[webtrekker]

Slight change of tack while I await further samples of acrylic to arrive.

I have some Mylar stencil material (transparent and cloudy) which I use for cutting stencils with my contour cutter, so I thought I'd give it a go as Mylar is, essentially, polyethylene and should print ok.

Well, it worked! Pressed at 190 °C for 60 secs. I may be able to reduce these times and temps.

vB_ID:5664

mylar_sub_print.jpg (93.16 KiB) Viewed 26 times

[knightweb]

Looks good
As you say, Mylar is Dupont's trade name for a modified PET, the PE bit being Polyethylene
Have you got any PET to try?

[pisquee]

190 seems high, should be able to back it down to 180 (we go as low as 160 for some fabrics.)
You may be able to get the times down to 30-45srcs too

[webtrekker]

[MENTION=5206]knightweb[/MENTION] - unfortunately I haven't any PET lying around but may get hold of some to try out now seeing as the Mylar was successful.
[MENTION=1209]pisquee[/MENTION] - Yes, I need to fiddle around with times and temps as I suspect my first attempt was a bit overcooked.

[Leadbelly]

Slight change of tack while I await further samples of acrylic to arrive.

I have some Mylar stencil material (transparent and cloudy) which I use for cutting stencils with my contour cutter, so I thought I'd give it a go as Mylar is, essentially, polyethylene and should print ok.

Well, it worked! Pressed at 190 °C for 60 secs. I may be able to reduce these times and temps.

Looks neat, what ink and paper did you use?
I did not know about Mylar and was wondering if my Graphtec plotter would cut stencils, or do you have a dedicated cutter.

You guy's have got my head working over-time when I should be on a deserted beach with two fishing rods:biggrin:

LB

[webtrekker]

[MENTION=9387]Leadbelly[/MENTION] - I use 125 micron stencil sheets. It can be easily cut, even with just a Cameo, as long as your cutter can use a cutting mat. One idea that I'm currently considering is making printed sleeves to slide over crush-proof mug boxes to make them more attractive to the customer.

The inks I use are the ones I use for all my sublimation work - from CIE, using their paper and ICC profile in my Ricoh SG3110DN printers. I get a much denser, more durable print than I got using transparency film in my Canon inkjet.

Mylar is tough and hard to wrinkle, yet cuts easily and can be creased. It's less than £1 for a 450mm x 600mm sheet (so less than 25p a sheet when cut to A4 size) and you could possibly do better than that by ordering in larger sizes or bigger quantities.

As for stencils, the Mylar is food-safe so can be used by cake decorators as well as the more basic uses on walls etc.