Re: [MW:12891] Paint drying for next coat.

Hi,

"Before performing coating operations, ambient humidity should be lesser than 85% and steel temp. more than 3 deg C above dew point."

above could be a reason that 1st coat didn't dry even exceeding duration specified in the product datasheet,

You are right to stop application of 2nd coat unless 1st coat is fully cured, in order to check "extent of intercoat cure" solvent rub tests are performed in accordance with ASTM D4752 for INORGANIC ZINC.

If 1st coat is not fully cured and subsequent coats are applied, BLISTERING may occur.

Regards

Manpreet Singh

From: Suresh <bobsuresh24@gmail.com>
Sent: Sun, 06 Nov 2011 03:25:06
To: materials-welding@googlegroups.com
Subject: Re: [MW:12869] Paint drying for next coat.

On Thu, Nov 3, 2011 at 1:02 AM, Vasantharao Pamula <vasantharao@yahoo.in> wrote:

Dear experts,

Can anybody give me guidance to accept the paint for next coats.

I work as inspector, i need to clear the painted pipes (primed) for 2nd coat.

When i go for inspection, contractor offered to me 1st coated pipes ( Jotun paint -Barrier comp.A, DFT required is 75Microns as per specification).

I observed a situation that contractor applied 1st coat, in few areas, patch-up work (repaint) has been done to get the required 75 microns.

When i touch the paint, it looks to me that paint has not dried. contractor claims that paint is applied 6hrs back, per data sheet of that paint 3h is enough for repainting.

Now problem is contractor is asking me to clear the 1st coat for next coats ( Pipe undergo 4 coat paint system). I ob-jected it as it looks paint is not dried.

Queries

1. Patch-up work is allowed on 1st coat?

༯div>

Yes ....It can be patch worked on 1st coat ..but it should be in minor areas ....make sure before patch work All slag materials removal and surface should be free from sand particals etc....

2. What is the min. & max. paint thickness allowed (75 Microns is nominal).

༯div>

Minimum 75 Allowed ..Maximum up to 120-150

༯div>

3. What is the testing method to clear the paints for next coats.

There is few methods are using ..please check your client paint specifications ...which power tolong,blasting etc....

༯div>

4. For Drying time, we should refer only painters data sheet?

༯div>

Yes ..it is Mandatory

5. When will be used tape bonding testing ( ASTM D 3359).

༯div>

As per Project specification/Procedue/Standard

༯div>

Thank you in advance

Rao.

08297552539

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Thanks & Best Regards,

Suresh

Mobile No: 91-92 92 905 905

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