Different Mug Grades and Coatings

Introduction

JG Electronics has been in the sublimation business since it’s inception in the early 1990’s and as such we have a wealth of knowledge to share.

We are starting a new series to give our customers the knowledge they need to make the best purchasing decisions.

Part of this series will include testing competitive products but we will not be naming the competitors as this isn’t professional.

We will also have the tested products in our branches so customers can see and touch them live as it were.

Part 1 - Mug Grades

Many industry players today tell their customers that there’s no such thing as different mug grades and that all mugs are A-grade. This is simply not true.

Mugs are made from clay or porcelain and are air dried. Once dry, glaze is applied and they are fired in a kiln at 800 + C. During the drying and glazing process it’s impossible to ensure uniform evaporation or heat absorption which affects the finished product. So when the mugs come out of the kiln they are hand sorted.

The more straight and uniform the mug is with no blemishes the higher it’s grade.

When the ear is lopsided, or the lip isn’t uniform thickness all the way round, or the mug isn’t dead straight, it is given a lower grade (see pics below). The more uneven the mug is the more uneven your transfer will be.

This is the reason we sell mugs of different grades. AAA mugs are by far the most uniform and the most expensive. You cannot buy cheap and expect the best quality.

Porcelain AAA mugs are even more expensive. We don’t sell them except by special order due to the high cost.

Mug suppliers (especially sublimation suppliers worldwide with only a few exceptions) only use B grade mugs due to cost and then sell them on as A-grade figuring no one will know.

See below for some details on how to identify the mug grade.

Part 2 - Mug coatings

We used to do all our own coating from the mid 1990’s to the mid 2000’s until the volumes made it viable to rather use dedicated coating factories overseas for our needs. Even when we were coating

Sublimation mugs are coated with a water based polyurethane or acrylic urethane. Mugs coated for laser transfers usually make use of a 2-part resin (often phenolic resin) which is thicker than sublimation coating.

Prior to be being coated the mugs are cleaned and an isocyanate based adhesion promoter is applied. This is essential to prevent the sublimation coating from peeling off the mug. The isocyanate is basically like superglue – it sticks to the mug and the sublimation coating sticks to it.

For sublimation, the thinner the coating, the harder it is and the sharper the resulting transfer.

For laser the thicker the coating the more durable the final print, but it can go yellow with too much heat and with age.

In the past the sublimation suppliers used to do their own coatings and the only coating which was DISHWASHER SAFE and DISNEY APPROVED was the RICH NEELY COATING. The only company in China who used this coating was Photo USA (we’ve been their distributor since 2006).

The DISNEY APPROVAL is important because it’s only awarded to a mug which is both FOOD SAFE and can withstand 2,000 dishwash cycles. These days everyone says their mugs are dishwasher safe when in fact they are not.

Photo USA since developed their own coating which has been DISNEY APPROVED and FOOD SAFE approved.

Up to five years ago most sublimation suppliers did their own coatings after buying the mugs from the mug manufacturer but then the manufacturers realised they could make more money selling coated mugs.

Today with very few exceptions (Bestsub, Photo USA and a handful of others), all coated mugs have the same coating since they are bought already coated.

See below for our accelerated dishwasher safe coated white mugs compared to a competitor’s dishwasher safe mug. There’s no comparison.

Part 3 - Colour change mugs

The original process was invented and patented by a guy in England (we’ve met him) more than a decade ago. He teamed up with Matsushita (Japan) and Neogene (UK) to make these mugs. Later he moved to Photo USA as Neogene leaked his secret.

Colour change mugs use Themochromic powder to make the colour change effect. This powder is unable to handle temperatures over 160C for over 2 minutes without starting to break down. This is why a colour change mug is always lighter after being sublimated.

What this also means is that a colour change mug is not and can never be dishwasher safe no matter what your supplier might claim.

Without getting too technical, the little thermochromic particles burst with too much heat reducing the colour change abilities. These mugs are also NOT UV safe. Even keeping them under direct indoor lights for a few years makes these particles decay.

The thermochromic powder is mixed into a base layer and applied after the bonding agent but before the sublimation coating. Matte colour change mugs are cheaper because less sublimation coating is applied.

The thermochromic coating is quite thick and to make the mug gloss, a lot more coating is required than on a white mug.

The colour change mugs currently on the SA market are briefly explained below:

1. Japanese coating – best coating – Royalties paid for its use – Mug goes completely white when hit. Cold colour is the most opaque. Best wash durability but also most expensive.

2. Chinese coating approved by the inventor – Royalties paid for its use – Mug is a little yellow when hot. Cold colour not as opaque. More affordable – this is the mug we sell.

3. Chinese copy of the coating – Not approved – Cheapest colour change mug, mug yellow when hot. Wash durability is dismal, coating starts washing off.

See below for our colour change mug which we clearly state is NOT dishwasher safe compared to a competitor’s mug which they claim is dishwasher safe.