Can I paint over Preschem’s Timber Preserver or No-Rot Gel?
No-Rot Gel
Yes. For best results allow the preservative to dry for as minimum of 24 hours. Use can then use a “builders bog” type filler and quality oil based primer then your choice of quality exterior oil or acrylic top coat.
Timber Preserver:
Yes, but with caution. Timber Preserver’s active ingredeint, Copper Naphthenate, is also used as a paint drier in oil based paints. As such it can be prone to colour bleed. To paint over Timber preserver we recommend the following:
- Allow at least 2 weeks to dry. Preferably more if practicable.
- Use a quality stain block type acrylic primer such as those made by Zinsser or Dulux
- If colour bleed through occurs with the primer, do not continue painting. Strip back the primer to bare timber and allow a further 2-3 weeks to dry.
Which reagent/chemical test can you use to detect copper naphthenate in a dried paint coating?
Hi Brendan, if it’s part of a paint coating if it’s used as a drier, then it’s very difficult to test for copper naphthenate as such. You can test for copper using flame emmissions spectroscopy if I recall correctly, but that requires a QC lab with expensive analytical equipment.
Regards
Rohan
On the Timber Preserver product page it says only oil based paints are recommended for painting over Timber Preserver but here it says an acrylic primer is suitable. Is an acrylic primer alright?
Hi Peter,
At the time the original claim was made, it was correct. But since then, there has been a significant improvement in resin technology with acrylics. Mst modern acrylic primers will work. I do recommend a stain block primer out of preference, to minimise the colour bleed from Timber Preserver. Mind you, if you’ve waited 3-5 dys prior to painting for the solvents to dry, then you shouldn’t have an issue.
Regards
Rohan