urethane over lacquer primer?

[tmsautoart]

Is it not advised to put a last topcoat of urethane primer over lacquer primer to seal and final sand before spraying color? I know that urethane doesnt shrink like lacquer does and I remember a buddy doing this on an old GTI of mine with good results.
OR,
Is lacquer out.... Does anyone use lacquer primer exclusively anymore? Its just so much easier to use in a garage and for cleanup over urethane.
Thanks all..
Terry

[chris911sc]

I personally always start with urethane compatible products from bare metal. It is not advisable to spray urethane over lacquer basically because lacquer reacts to temperature. Urethane stays in its current state, once fully cured, regardless of temperature (other than a little shrinkage from the solvents). With temp changes, the urethane topcoat will evetually fail over a lacquer undercoat because lacquer can become soft with extreme heat. A PPG paint rep told me if you must spray over lacquer, to atleast put down a urethane sealer or primer. That will give the paint better longevity.

[tmsautoart]

thanks. So does anyone still use just lacquer primer anymore? I'm tempted because of the ease in use and cleanup...and price.

[chris911sc]

Im sure some people still use lacquer products. In the collision repair field it is pretty much extinct except for some small shops. I would bet there are a few rat rod/hot rod shops that still use lacquer.

[tmsautoart]

urethane it will be... I'll just miss the ease of using lacquer primer and leaving the leftovers in the gun without it hardening for a while.....cleaning the overspray off w/ thinner...oh well.