Issue on ceramic mugs

[Nessaroo5]

I have coated mugs successfully with DCC, but as of late I have had 9 come back with damage from the dishwasher/microwave. 

 

1. Sand mug with 220 grit 

2. Wash with dawn and air dry 

3. Clean with isopropyl 91% - air dry

4. Paint with alcohol inks and isopropyl 91%

5. Dry 18 to 24 hours min

6. Spray 3 coats of kamar varnish

7. Gas off minimum 24 hours

8. Coat with 2 to 3 coats of DCC.

 

I'm at a loss why these are suddenly failing.

 

[KBS Coatings]

How do you apply DiamondFinish Clear? Brush? Air brush?

 

We are looking forward to your reply.

[Nessaroo5]

I brush on with a high density foam brush

[KBS Coatings]

We have never tested DiamondFinish Clear in a microwave, but we have never had problems with the top rack on a dishwasher only if the DiamondFinish Clear is fully cured at least seven days and the DiamondFinish Clear was applied in thin and not heavy coats.

 

Can you pin down for us the cause ... dishwasher top rack or microwave?

[Nessaroo5]

Dishwasher top rack heated dry off. Microwave also.

 

I hold on to the mugs a minimum of 4 days before I mail them and include a care card with a cure by date of at least another week. 

[KBS Coatings]

OK. We will do some testing on the microwave part of this. We have tested the top rack of dishwasher and that is no problem, but we have not tested the microwave. We will report back once we have our testing complete.

[Nessaroo5]

Thank you.

 

Any reason why a mug would come out of the shipping box with the finish bubbled up? It did not go in the box that way. 

[KBS Coatings]

The micro-bubbles are an indication that the clear coat was still trying to cure, and the packaging caused the full cure not to happen. You can avoid this by allowing the surface to cure before packaging and you can speed up the cure by adding humidity to the environment after the initial flash off.

[Nessaroo5]

They said they weren't micro bubbles but larger "pockets" - same reason? 

[KBS Coatings]

Please post some pictures so we can see that and research.

[Nessaroo5]

This is the best pic I received from them

[KBS Coatings]

Thanks. The picture does not show much so it is hard to tell. Our coating has not changed in a few years so we can rule that out. Have any of your other coatings changed? Maybe the varnish?

[Nessaroo5]

No. Always 3 - 4 coats of kamar first. Then the dcc. I've been using it since Feb and have only had issues for orders in the last month and a half. 

[KBS Coatings]

Be sure to stir DiamondFinish Clear for two minutes before each use. That is a common mistake.

[Nessaroo5]

Ok I do mix it but not for 2 min. I can add that in.