When it comes to painting, earlier decade the contractor use to dilute the paint by removing paints from drum and injecting the water from below of the drum at center with injection as the site supervision team was very strict to ensure dilution ratio and painted surface finish.
Now a days such trick is not used by painting contractor as its known to everybody. but they can fool us by diluting more at site due to less amount of supervision and lack of knowledge by site supervision team.
To check the Quality of Incoming paint material you can have following measures implemented and recorded at your site.
1. Review of MTC (Manufacturer test certificate) - we should take the MTC with each lot we receives at site and review it by verifying the batch details.
2. The drums are sealed from top, we should check for any damages to top cap and also any sign of dilution at bottom of the drum.
3. We should take the weight of approved sample bucket at the start and verify the wet of new lot buckets is same as of the approved sample bucket - huge variation will indicate the malpractice and can be verified by getting it tested from third party.
4. We should record the details of the batch we received along with its expiry date.
You can tabulate above data to form a test report for the lot of paint received.
If the top management is serious about the quality of the paint finish, you can discuss following with top management to ensure better finish and quality of paint.
In general, type of paint and brand is finalized base on the rate and the coverage parameters of all brands.
First the comparison of rates is done as cost per sqft and then some brands are finalized for doing sampling works.
All paint manufacturer are smart enough to market their product, hence to show what they claim is achieved at site, they do manipulate the sample which is sent for doing painting which obviously gives coverage of more than what was specified in their technical data sheet.
The report submitted by Quality department on sample works makes everybody happy and the product get finalized base on other observations along with economy.
Now here the real critical part comes, from here the all calculations starts to get messed because at actual work conditions with arrived lot the coverage is not get achieved and in fear of debits the contractor do start diluting more and more to adjust the stock and reconciliation of it. this practice leads to unpleasant finish of paint which is further become subject of Quality of paint where manufacturer blames on applicator and applicator blames on manufacturer. finally this comes to Quality department for what test you did to ensure the quality of paint or application of it.
The short and sweet answer for all of the above is.
After doing finalization of the paint brand base on coverage achieved or stated in TDS, the purchase order or work order should have the following clause which makes binding to manufacturer or contractor.
On receiving of new lot at site, the sampling will be done to check the coverage to the paint randomly from any drum in lot.
The Applied paint of wall surface should give the same coverage (+/5 %) with same tone.
In case if the observed coverage is less than what specified, the calculation on the basis of coverage will be done for reduction in quantity of paint received at site.
The above clause will eliminate the offering of the Work or Purchase order to such trick manufacturer or contractors.
The site team should then ensure the same tone and texture is achieved (it will be then direct indication of lack of supervision in cases the paint application looks unpleasant).
This is difficult but not impossible to achieve in places where Quality is more important than calculations of rates per sqft because final outcome is known prior to get trap in tricky peoples who plays well to achieve cost per sqft by manipulating the painting samples and doing false commitments which later converted into blame game.
Hope this answer helps you in understanding, how the quality of paint can be checked at site and what kind of records for tests you can keep.
