first try at Decals but need help !!

[Shades of Colour]

Im sure you guys will be able to answer my very silly question.  I recently attended a glass class and we put decals onto our bowls.  I'm sure the lady running the course said she would fuse the piece and then slump it!!  Obviously with all courses we go home and a week or so later received our fused items!!  I was under the impression that the decals would just be fused using the same schedules for tack or full fusing.  I've just bought some decals from warm glass and they have come with completely different instructions and firing schedules!!  Can someone let me know if I can fuse these on using a tack/full fuse or do I need to do another firing?  Thanks so much for your help?

[Glyn Burton]

It would be normal to fire decals separately after fusing and slumping, if you think about it the images would deform as the glass moves. Just follow the manufacturers instructions, its what they are there for.

[SueP]

Not got my schedules at home but I tack fuse decals on to the base sheet and then top and full fuse as normal with no problem - hope that helps

[Zeldazog]

It would be normal to fire decals separately after fusing and slumping, if you think about it the images would deform as the glass moves. Just follow the manufacturers instructions, its what they are there for.

That surely depends on the decals... the ones I use don't fire properly until around 750 (any lower and you can still see the 'glue lines' - but if you took a dish to that temperature after slumping, you'd be back to flat.

[Glyn Burton]

I would re-fire the piece in the mould anyway. When I make decals I use enamels which mature at lower temperatures about 600 if memory serves, screen printing on to thermoflat paper and overprinting with covercoat.

[Zeldazog]

If you refired, in a mould or not, there's a fair chance of distortion of the edges of the piece at 750.  Believe me, I know (Tried to fire polish and slump at the same time, ooops)

I fire the decal on before slumping, but that's because of the temperature decal I use.  If I used ones that matured down at 600, lower than slumping temperatures, then yes, I'd do it post slumping, as I wouldn't want to burn out the decal.

Not used or even heard of thermflat paper - would you be kind enough to share a bit more info Glyn?

[Shades of Colour]

Thanks for your help everyone.  I had already put some pieces into the kiln to fuse so these ones were going to be separately anyway.  I think they were low temperature ones but will have another look.

Thanks again

[Glyn Burton]

Thermoflat is a paper printed with gum on one side, The image is printed on to the gummed surface and allowed to dry. The print method could be silk screen, lithography, letterpress it doesn't really matter the ink is made of glass enamel and a binder. Once the print has dried it is over printed with covercoat a liquid plastic which dries to form a thin skin.

To use the decal or transfer the paper is put into warm water which causes the gum to dissolve and allows the image with its covercoat layer to slide off, at this point it looks like a piece of cling film with the image on. This is smoothed on to the surface of the glass making sure that there are no air bubbles. Once dry the piece is fired the covercoat burns away and the image burns into the glass.

Its all a bit long winded and the covercoat is very smelly but it allows you to reproduce complex imagery on to your ware 98% of the patterns on your pottery will be done this way. I don't make them very often only if I have a special job, and I am lucky in that I can use the print facilities at the college I teach at when I need them

[Zeldazog]

Ah, so it's probably what they use for the decals I order then, I know the stock ones are usually screen printed (the detail is better and the colours are usually much richer than digital print decals, although I am guessing they are printed onto something similar too)

Thanks Glyn