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View Full Version : ? Realistic Minimum GSM for ZERO buckling with acrylics on Paper ?


Petdevils
10-21-2006, 08:54 AM
Hi,

I've just used the first sheet of a pack of 25 i had bought on the advice that 300gsm paper will take as much acrylic as you want to use. This evening, all I did was took a sheet of C/P watercolour paper and scrubbed in my dark background layer. Simple after this the entire thing is buckling and i am in a bit of shock.

What I'd like to know is the minimum realisitic GSM(eg 450?) that I should buy that should really show no sigh of warping/buckling (mostly in watercolour papers so should be able to take it?)

p.s i haven't primed the paper as I've been assured you just don't need to on watercolour papers as long as they are 300gsm or more... or was that bad advice also?

Thanks

Lady Carol
10-21-2006, 09:51 AM
I am surprised too. It should have warped slightly but not buckled. Are you absolutely certain that it was 300gms/m2? This is the paper the watercolour people use without prestretching the paper before they use it.

Petdevils
10-22-2006, 05:05 AM
G'day Carol,

Positive, the paper is still int he plastic from the manufacturer with their sticker/codes etc. had the pack unopened shipped to me with other orders, it is Lana Aquarelle 25% cotton C/P 300gsm, 50 x 65cm. So I'm kinda regretted buying the other 24 sheets at the moment ?

does the cotton percentage play any part in likelyhood to warp?

The background scrub couldn't really have been thinner, not even half opaque and it curled out like its trying to hug itself if you get me. But its so bad that before I had even finished covering the sheet it was ready to fall off my easel and I have a 10cm lip!

i'm wondering now if i try to gesso the rest of the sheets before using them; will that help prevent or just make the warping worse?

Is it possible I got a really dud batch, or if this happens - this is why i'm hoping to find out the realistic minimum weight i shoudl buy in the future to avoid all this?

p.s. sorry this is such a whiney first post in ages, i was just really looking forward to finally learning how to paint lol :)

Cheers.

Einion
10-22-2006, 01:04 PM
What I'd like to know is the minimum realisitic GSM(eg 450?) that I should buy that should really show no sigh of warping/buckling
80.

But then I'd be stretching it :D

Einion

Richard Saylor
10-22-2006, 03:25 PM
Without at least taping the paper around the edge to a rigid board, most watercolor paper can warp or buckle if one side gets really wet, such as might happen if wet paint is scrubbed into the paper. I've even had 640 gsm pull away from the tape (masking tape around the edge).

Most of the time, if 300 gsm paper is taped around the edge, it will warp when wet but flatten out satisfactorily while drying.

As Einion said, you could stretch the paper, but that's a hassle I'm not willing to do. Also, you could glue the paper to masonite or MDF.

Richard

DianaQu
10-22-2006, 03:39 PM
you may have confused 300 gms paper with 300 lb paper, which is very different. I paint with watercolor and acrylics on 300 lb (that's 640 gms I believe) with only a little warping if i use a LOT of water/paint.
on the other hand, 140 lb paper (300 gsm) needs to be taped down in order for it not to buckle.

dq

Lady Carol
10-22-2006, 07:18 PM
you may have confused 300 gms paper with 300 lb paper, which is very different.
This may be the case but as you were quoting metric numbers it is unlikely going to be 300lb 300 gms/m2 is equivalent to 140lb/sq.inch. To use 300lb/sq.in the paper would be substantially thicker.

I paint with watercolor and acrylics on 300 lb (that's 640 gms I believe) with only a little warping if i use a LOT of water/paint.
on the other hand, 140 lb paper (300 gsm) needs to be taped down in order for it not to buckle.
I use 300gms a lot of the time and I haven't had any trouble with buckling only a little bit of warping.

PetDevils: I don't know what else to tell you except, give gessoing a go.

Incidentally, how thick is the paper. It should be fairly stiff to begin with.

Ian Bruce
10-22-2006, 11:46 PM
Did you use water or medium to thin the acrylic for the background layer? 300 gr is 140lbs, and 140lbs watercolor paper will not handle a lot of water without buckling. I understand that if you use medium rather than water for your underpainting, buckling is minimal. That seems to work for me--it makes the first coat a prime coat. I do think that you would still need to tape it down. I hate any buckling at all and when I do watercolors on 140lb I always soak the paper and staple it to a board which stretches it taut when it shrinks. 300gr (140lb) paper seems to behave very well when purchased in block form, particularly if medium is used to thin the ground. 300lb is what watercolorists usually use if they do not wish to stretch the paper.