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The tech sheets (also called P-sheets or product data sheets) will not give safety information. For that, you'll need to get the MSDS (material safety data sheet) associated with the products. They are also available on-line from PPG and DuPont and probably other paint manufacturers as well. We had an interesting series of discussions here a while back concerning the safety recommendations published by Valspar. I considered their MSDS sheets that we looked at to be inconclusive, confusing and misleading. In my opinion they were useless to anyone trying to make a decision on what to use for respiratory safety when using their product. I have not found the same to be true of either PPG or DuPont. They seem to be pretty honest, straightforward and conservative (and clear) concerning the safe use of their products. No paint product is good to breathe so a standard cartridge mask is usually considered advisable and satisfactory for products not containing isocyanate compounds in any of the ingredients. Hardener additives added to enamels and urethanes all (as far as I know) contain isocyanates. If you want to be sure, at least as far as you can trust the manufacturer, you should get both the tech sheet and the MSDS sheet for each product. The epoxy is a notable exception regarding isocyanates. It is a two-part product requiring the addition of a catalyst but that catalyst, unlike topcoat hardeners or "activators", does not contain isos. No, the OMNI MAE w/o hardener will not let you scuff later and recoat with more MAE - at least within a reasonable time. There is a danger of wrinkling and lifting of the previous film. Such recoating is not addressed at all in the MAE tech sheet. I have asked PPG about recoating OMNI MAE w/o hardener in the past and they have told me they do not recommend it - at all - period. I can't say for sure since I have never attempted it myself. Enamels used without hardeners "dry" in two phases. The first is evaporation of the solvents, which makes it dry to the touch and is dry by conventional meaning of the word. This happens within a day or so. The second phase is an additonal "drying" process that takes place by oxidizing of the paint film in being exposed to air. This second phase is properly referred to as curing. It is dependent on temperature and can take several months to complete. Between the initial dry and when curing is complete, many unhardened enamels are susceptable to attack from solvents in any film applied over them. How severe that attack is probably depends on time, temperature and how aggressive the solvent is. The classic example is a gasoline spill on fresh, but dry, unhardened enamel. Wrinkling of the film is very likely and stripping and repainting will probably be required. Some of the paint solvents used have undergone changes in recent years, I think mostly because of environmental air emission regulations, that also make them less aggressive and less likely to cause wrinkling under those circumstances. I believe the NASON and Centari products fall into that category - and recoating is addressed specifically in the tech sheets for them. If you do use the MAE w/o hardener and need to do some repair afterward, yes, you might be able to spray a single coat of epoxy as a sealer prior to recoating with MAE. I think you would be successful with that but I can't say for sure since I have never tried it with uncured MAE. Years ago, PPG marketed a special sealer just to permit the recoating of unhardened enamels. They no longer do, presumably because of low demand, since unhardened enamels are no longer used in the auto-refinish world. The technical data sheet (in pdf format) for OMNI MAE w/o hardener is here. The MSDS for it (also in pdf) is here. If you want help in getting other tech sheets or MSDSs for any PPG or DuPont product, post back and someone will assist you. Rod
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Rod