Testors Dullcote lowdown:
1) It is a lacquer, not a varnish: This means that the solvent in it is nitrocellulose (lacquer). Nitrocellulose can lift paint, so it's best to varnish first with a non-lacquer gloss coat then apply testors (remember that testors glosscote is also a lacquer).
Generally you wont have any issues of paint lifting - i've never had it in 4.5 years and out of thousands of customers we've had it reported had a dozen times IF that. BUT, it can happen, so be aware to avoid issues..
The problem is more prevalent with metallics due to the different nature of those paints.
Decals will be utterly and irretrievably destroyed by neat testors - as learnt the hard way :-(
2) Lacquer does yellow.
Lacquer DOES yellow over time and under prolonged exposure to UV light - but then so do many varnishes even those listed as "Non-yellowing". Similarly paint can fade and yellow under UV - so even if the lacquer or varnish doesnt change colour the paint underneath may.
This makes it really hard to determine what is yellowing... but, bottom line is that lacquer CAN and DOES yellow over extended time periods (just ook at antique lacquered furniture for a classic example - then again its antique so...)
The requisite time period and amount of UV exposure for Testors to yellow is considerable - we have left a model in direct sunlight for almost a full year now and notice no changes - do the same in Australia though and you may obviously get a different result to "sunny" UK.
We have not yet had a single customer report yellowing to us in 4.5 years of selling it (obviously that doesnt mean it never happened though - if it did they just didnt tell us!)
3) lacquer is much tougher than varnish - it just is - it's very tough.
4) Sake the can very well and regularly
The matting agent in testors is very heavy and settles very quickly - so shake well and keep it shaken.
A common "complaint" is that cans of aerosol testors staart off matte but go satin after some time. This is a sign of mixing/shaking not being done properly - most of the matting agent has been used early in the can life and toward the end you are spraying low amounts of matting agent and more carrier/solvent. The solvent/carrier is nitrocellulose - and that is gloss - hence satin finishes when not thoroughly mixed.
5) ALL aerosol varnishes and lacquers are temperature sensitive:
The following can cause problems, especially "whiting":
a) Spray from a warm can to cold figures
b) spray from a cold can to warm figures
c) spray in the cold
d) spray in high humidity
e) spray in low humidity
'orrible list, applies to all aerosols - the only way to be sure is to use a test figure before spraying. The most common "mistake" is when folks spray outside - taking a can from inside the house (warm) and spraying outside where it is colder OR spraying on to figures outside which are cooler than the aerosol - that's most often where you get whiting as the dry-rate of the aerosol is affected causing the whiting.
I think that's about it really - remember that most things, even the above, are not scientific but anecdotal, so there are no guarantees.
Having tried many dozens of brands of varnish I personal do recommend Testors Dullcote as a reliable matte finish - BUT you really must be aware of the issues.
Nowadays we dispatch a small list of information (similar to the above) with every can so that folks know what can go wrong.
better to be forewarned we think.
No aerosol is 100% reliable though which is why whenever you ask aon a forum about "the best matte varnish" you always end up with the extremes of great and awful for every varnish - sooner or later somebody somewhere will have had a disaster with an aerosol of any brand.
It's just one of those things you have to accept if you use aerosol varnishes (and lacquers) - so "use a test figure first" every time, si the only way to be sure.
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Apologies for the long post and if i seem as though i'm preaching etc - hopefully though some of that is useful.
15 May 2007, 01:23:42 PM