You are not logged in.
Hi all
Been having a mad making session and I've been getting the odd air bubble in the curve part of my bowls. I've made sure the layers are wet with glue so its not dry patches and when I'm layering I brush the layer nice and flat. However When i get up in the morning that bubble fairy has been out to play 
Any help or ideas would be appreciated.
Sue
Offline
What kind of adhesive are you using?
Are you pressing the layers down firmly with your fingers, or just gently with the brush so as not to get your fingers sticky?
Sue
Offline
Hi Sue
I'm using PVA mix with water. I brush quite hard, all the other parts are fine its just the inner curves. I don't mind sticky fingers so i will give that a go, I'm usally covered up to my elbows with glue . Do you think it might be because several layers are news print and others are kitchen roll :?:
Sue.
Offline
Hi... try using a pin or a needle, puncture the part with air pockets... squeeze out the air then brush it again with glue on top... or better yet, dip your thumb in glue and massage it... >Eric
Offline
Thanks for that but i've already tried i ended up cutting it with a knife putting glue in and clampping it closed. it made a bubble next to it The layer is quite thick about 4-6 layers and its separated from the other layers I'm a bit worried if I really soak it the bowl will deform.
Sue
Offline
... so you already performed surgery and there are complications?... how about trying a PVA transfusion in between the layers that separated?... if there's another complication maybe you need to amputate it... I suggest another 4 to 6 layer transplant... use pulp or gesso to even up the surface.
... soak it up, PM warps when it dries too fast. If your leaving it overnight cover it with plastic or a semi-heavy cloth... you can ask Sue (CatPerson) or Dave for a second opinion... >Eric
Offline
... let it dry slowly, keep massaging... >Ditto
Offline
I know David and some of the others who strongly believe in PVA won't agree :shock: , but that is precisely why I hate PVA. I hate how it warps :evil: and I hate the bubbles :evil: . I flat out won't use it any more. More and more, I am of the opinion that plastic glue and paper don't work together except as a final protective coat. Maybe. :?
Is there any chance you could find some cellulose wallpaper paste? Keep the bowl you've got, and try the methyl cellulose paste (fairly thin) and try the same project and combination of papers, and see which one you like best. There's no comparison, IMO.
An example: I covered a child's ball (about 8"/20cm diameter) with only three layers of tracing paper and methyl cellulose adhesive. No letting the individual layers dry, just three layers right on top of each other, then I hung it to dry.
It was gorgeous! All the paper laid perfectly flat -- none of those stupid curled-up edges or corners. There were some wrinkles in it, but I attributed that to the very fast job, as it was just an experiment. All the paper held together perfectly, no pulling apart. Because it is so thin, it does flex, but no cracking, no delaminating, and if I dent it with my finger, I can pop it right back into the curve of the sphere. More layers of other paper (esp heavier or thicker) don't flex, and it's very strong. I just love it.
About your question of mixing types of paper: I've never done that, so I don't know if that is a contributing factor, but I am thinking it's not. I got results like you're getting using just a single type of paper.
Sue
Offline
Hi,
I am intrigued as I have not yet encountered airbubbles. Like Sue I am a fan of cellulose based paste and tend to use my hands to meld the paste and paper together, except when using tissue paper when I resort to a brush.
It definitely sounds as though the plastic of the PVA is fixing the paper so that you can't deflate the bubble. How are you getting on? Have you had to start again?
Charlotte
Offline
I get air bubbles with flour/water paste and with pva/flour/water and pva/water. It's a conspiracy against PMers! heh
Offline
I've heard of many other people who mix PVA with other adhesives, but I don't know why. There is no insult intended here. I just don't understand how flour or cellulose or anything else is going to improve the results of PVA as a glue. And methyl cellulose is fine as it is, as long as it isn't mixed too thick. I've never used flour/water much, due to the bug infestation problem, and my extremely humid climate.
One thing my brain keeps returning to: when PM was at its peak in the 1800's, a LOT of PM was being cranked out with either no adhesive at all (just moisture + pressure), or with a type of adhesive that allowed moisture to work its way out to the surface until the piece was dry. That's all they had, so that's what they used. Now people use a plastic glue that dries on the surface fairly quickly, trapping moisture inside. I simply don't see how this can be an advantage.
One thing on the bubbles that just occurred to me (bear with me on this). I also work with concrete. If I put a thin (1/2"/1+cm) layer of concrete on a plastic or inflatable object, let it cure in shade, then place it in sunlight, the sunlight gradually warms the air inside the inflatable and the air expands, cracking the concrete.
If a PM project made with PVA is made with layers that are allowed to dry between layer applications, and especially if it's placed in the sun (even indoors), could an air pocket within the layers expand and help to form the bubbles?
Someone once said that you can argue with the laws of physics all you want, but you're going to lose. In my years of working with PVA/PM, have I been fighting the laws of physics without even knowing it??? 
Sue
Offline
Hi all
Ive read through all your thoughts & ideas. Thank you all very much and after having read them I will give the cellulose wallpaper paste a go I also think having read what you have said I'm drying it out to fast.
I have got most of the bubbles out with major surgery and clamps and as for the other ones, I'm going to be the only one who will notice (apart from you guys ).
So my next bowl i will use paste and dry slowly and let you know how i get on.
The great thing in life is you have always got something new to learn.
Sue.
Offline
.. that's the spirit!... made a few bowls with pulp (corn starch & water- glue)... no bubbles only a bit of warping and cracking... >Eric
Offline
I have not used pulp yet :shock: its on my to do list this year.
I've started collecting egg boxes as I quite like the egg box pulp Melf talks about in the information section.
Before that happens i need to shut my head up I've got so many ideas I'm either drawing or messing about with PM.
The only pulp I sort of use is all those straight edges that I rip off and store I grab a handful of them and dunk it in glue squeeze out and splodge on, it's sort of pulp ?
Offline