PVA neutral PH or normal???

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PVA neutral PH or normal???

Postby thecreative » Tue Jun 04, 2019 3:01 pm

Hi all,
as per a previous post I'm mounting my artwork (inkjet canvas) direct onto 6mm mdf with Arcare ph neutral adhesive ready to be overpainted in acrylics, this is the only one Ive tried and it does appear to do the job well but it is a lot more expensive than standard pva.

Question is do I need to use neutral ph? and as this states excellent layflat properties will others work as well?

Cost is an issue in the project I'm doing but at the end of the day I want it right, anyone recommend a cheaper alternative adhesive?

Thanks
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Re: PVA neutral PH or normal???

Postby Not your average framer » Tue Jun 04, 2019 3:49 pm

How thick is your MDF? If you are only sticking the paper to one side, you should consider the potential for the MDF to bow as the PVA sets dry. I don't have any particular figures for you, so you will have to use your own judgement about this, but if you are only gluing the paper to one side of the MDF, you should expect the potential for bowing to be more of an isuue on thinner MDF, as opposed to thicker MDF.

If you are going to stick paper to both sides of the MDF, to counter the tendancy to bowing, the paper needs to be exactly the same paper on both sides and oriented of both side with the same direction of the grain in the paper. I'm not particularly pursuaded that neural pH PVA is going to stay neutral pH considering the fact that the MDF is far from either neutral pH, or free of other undesirable contaminants and some of these may be made mobile by the water content in the PVA.

On the other hand, the PVA does have a measure of waterproofing once it has set, but at least some PVA's are to some degree hydrosopic, if exposed to water after the PVA has set. I suspect that at the end of the day, that it's not too much of an issue, one way, or the other. It may be cheaper to use a reasonable thickness of MDF and only stick the paper to one side, or to use thinner MDF and stick the paper to both sides, but it won't be difficult to work out which is going to be cheaper.
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Re: PVA neutral PH or normal???

Postby thecreative » Tue Jun 04, 2019 4:27 pm

Hi Thanks for that, at the moment pieces are smaller at 400 x 300, 360gms inkjet canvas to one side only, 6mm MDF but I'm hoping to increase size to a max of a1.

Worried about weight if I use 10mm mdf, not really bothered what the substrate is I'm open to suggestions if there is anything lightweight and solid ?

Thanks for the input much appreciated.
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Re: PVA neutral PH or normal???

Postby Not your average framer » Tue Jun 04, 2019 4:51 pm

I would expect 6mm to be o.k. for the 300mm x 400mm, but I'm not so sure about A! size. I think I would start with the smaller size and work up in size and see what happens.
Mark Lacey

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Re: PVA neutral PH or normal???

Postby thecreative » Tue Jun 04, 2019 5:02 pm

Thanks Mark that's the intention, 6mm seems to be working fine and the pva is spot on I was mainly interested to see if cheaper pva would be as good, difficult to know from there product pages as this is the only one advertising excellent layflat properties.

Any suggestions for anything other than mdf to mount onto, Ive though of dibond or similar but again the mdf id low cost and I know it works.
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Re: PVA neutral PH or normal???

Postby prospero » Tue Jun 04, 2019 5:20 pm

Anything up to that size, 6mm is OK. Anything bigger I would think about using stretcher bars. :)

The problem with thick MDF is, it's less likely to bow, but if it does you aren't going to flatten it in a hurry.
If you used 2.5 MDF then you can at least 'persuade' it a bit.

As for the Ph properties of the glue - I wouldn't lose any sleep. :lol: I've used Unibond to do similar and it's as good as anything.
The main thing is to keep it under even pressure until the glue has well and truly set. At least 24hrs I'd recommend.
An improvised press using two sheets or 19mm MDF/Chipboard is a good way. Release paper and a foam blanket to even the pressure.
Pile whatever is heavy and handy on top. Empty the book shelves.

Btw. Sealing the back with an coat or two of PVA prior to mounting is a good idea. :wink:
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