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Varying Water Retention Rate on Same PVA Sponge

Fully Wet Sponge
Fully Wet Sponge

The water retention rate of a PVA sponge varies from case to case. We have show our reader some study about the wide variation on water retention rate in the article water retention consider as reference spec. Today, we repeat the same test but on the same PVA sponge.

The test shows the difference of water retention amount even on the same PVA sponge. Perhaps, the difference could be huge.

How much difference about water retention rate against the same PVA sponge? 10%, 20% or more?

Same PVA Sponge Absorption Rate Comparison
Same PVA Sponge Absorption Rate Comparison

Water Retention Rate

In earlier test, we had examined that a sponge may have difference water retention amount. The difference not only appears in the total water retention but also the retention rate.

Water Retention Mechanism

In our previous study, we did reveal that the water absorb and contain in the porous waterway in the PVA sponge. Unfortunately, due to the air bubble trapped in the sponge, and becomes a pocket blocking water storing in the sponge. This affects the water retention.

Taking out the air pocket in the PVA sponge is a necessity process if you want to measure a precise water retention amount.

The Testing Conclusion

In this experiment, we are soaking the same PVA block sponge to compare the water absorption amount. From the above comparison chart, we could easily see that even though same block sponge, but they are experiencing a significant difference in water retention amount.

Removing the air pocket becomes a great challenge for user who want to perform soak test. Base on the above explanation, we foresee a thicker sponge is having a larger in variation because the unseen air pocket.

Squeezing the sponge several time definitely helps to break-up the air pocket but the excessive mechanical force may also having risk to deform the sponge. In general, the PVA sponge is pretty robust in sponge hardness and able to resume to it original structure after soaking in water. But this is not a wise method if you are using for judging a sponge quality.

Our Next Move

Now we know the root cause which affecting the water retention. Taking away the inherent air pocket in the PVA sponge is the only way to acquire an accurate water retention data. There is a standard way for achieving this scenario.

Water retention rate is always a reference parameter due to large variation because of poor repeatability.

Unless we are very sure the air pocket is removed, else the water retention rate and relevant data for the PVA sponge is meant for reference purpose.

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